Impacts of the

Covid-19

Pandemic on

Flight Safety and

Pilot Proficiency

An investigation of Australian Flight Safety Occurrences and

United States Self Reporting

Rory Buchanan

02/06/2023

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

Abstract

This study examines the impact the Covid-19 pandemic had on flight safety occurrences in both

Australia and the United States. The Covid-19 pandemic saw drastic falls in the activity levels of

aviation operations worldwide, with total aircraft activity falling to a third of their 2019 levels in April

2020. In Australia flight activity fell by more than eighty per cent, while in the United States aircraft

movements fell seventy per cent.

Utilising the Australian Transport Safety Bureau’s National Occurrence Database and the US National

Aeronautics and Space Administration’s Aviation Safety Reporting System, this study examined flight

safety occurrence rates and types to determine the impacts of the Covid-19 pandemic on flight

safety, and whether pilot proficiency was adversely impacted through the imposition of public

health measures such as lockdowns and remain at home directives.

The pandemic caused a rise in occurrence rates in both Australia and the United States with

Australian rates remaining elevated through 2020 and 2021 in the face of continuing pandemic

related restrictions, while the US saw a return to pre-Covid trends by late 2020 as flight activity

began to recover. This study identified a potential link between increases in both flight activity levels

and occurrence rates as potentially related to flight crew proficiency. The long-lasting and severe

lockdowns seen in Victoria saw a continued adverse impact on the frequency of flight safety

occurrences when compared with other Australian jurisdictions throughout 2020 and 2021, while

the United States with its relatively lax public health measures saw flight safety occurrences

relatively quickly return to pre-Covid levels.

AVA80037  Impacts of the Covid-19 Pandemic  Rory Buchanan 
Aviation Research Dissertation  on Flight Safety    101121216 
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Contents 
Abstract ................................................................................................................................................... ii 
Chapter 1 – Introduction ......................................................................................................................... 1 
Background ......................................................................................................................................... 1 
Relevance – Wasn’t COVID-19 a once off? ......................................................................................... 1 
Scope ................................................................................................................................................... 1 
Chapter 2 – Literature Review ................................................................................................................ 1 
Recent Experience Requirements ....................................................................................................... 1 
Covid-19 Effect on Flight Recency ....................................................................................................... 3 
Existing understandings of how Covid has impacted flight safety ..................................................... 4 
Direction .............................................................................................................................................. 5 
What now? .......................................................................................................................................... 6 
Research Questions ............................................................................................................................ 6 
Chapter 3 – Methodology ....................................................................................................................... 7 
Data Sources ....................................................................................................................................... 7 
ATSB NAOD ......................................................................................................................................... 7 
NASA ASRS .......................................................................................................................................... 7 
Limitations of Data Sources ................................................................................................................ 7 
Selection of Datasets .......................................................................................................................... 8 
NAOD .................................................................................................................................................. 8 
ASRS .................................................................................................................................................. 10 
Occurrence Rates .............................................................................................................................. 11 
Chapter 4 – Results ............................................................................................................................... 11 
NAOD Occurrence Rates ................................................................................................................... 11 
ASRS Occurrence Rates ..................................................................................................................... 28 
Chapter 6 – Discussion .......................................................................................................................... 31 
Did the Covid-19 related downturn in aviation activity result in a higher rate of safety occurrences 
in Australia? ...................................................................................................................................... 31 
Did the severity of Covid-19 restrictions in Australia result in a greater variation in the rate of 
safety occurrences than in the United States? ................................................................................. 32 
Did the longer lasting and significantly harsher restrictions in Victoria, compared with the other 
states and territories, result in a greater change in occurrence rates? ............................................ 32 
Has any variation the level of safety occurrences plateaued at a new level or is the level similar to 
the pre-pandemic levels? .................................................................................................................. 33 
Which sectors of the industry saw the greatest effect of pandemic-related occurrences? ............ 33 
To what extent can loss of pilot proficiency from reductions in flight hours explain variations in 
occurrence rates? ............................................................................................................................. 33 

AVA80037  Impacts of the Covid-19 Pandemic  Rory Buchanan 
Aviation Research Dissertation  on Flight Safety    101121216 
Human Factors  and Pilot Proficiency 
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Beyond Covid .................................................................................................................................... 34 
Conclusion ............................................................................................................................................. 35 
References ............................................................................................................................................. 36 
 
Figure 1 2019 and 2020 Total flight tracking data Flightradar24.com................................................................... 3 
Figure 2 Commercial flight tracking data Flightradar24.com................................................................................. 3 
Figure 3 Flightradar24.com .................................................................................................................................... 3 
Figure 4 Flightradar24.com .................................................................................................................................... 3 
Figure 5 Estimated total monthly flight hours, overlaid on Covid-19 lockdowns and restrictions.......................... 9 
Figure 6 Estimated monthly flight hours of RPT and GA fleets ............................................................................... 9 
Figure 7 Melbourne Airport Movements, with indication of Victorian Covid-19 restrictions ............................... 10 
Figure 8 ASPM 77 Airport movements, with WHO covid pandemic and Covid-19 endemic (Achenbach and 
Pietsch, 2022) periods overlaid ............................................................................................................................. 10 
Figure 9 All occurrence rates each year ................................................................................................................ 12 
Figure 10 RPT occurrence rates each year ............................................................................................................ 12 
Figure 11 GA occurrence rates each year ............................................................................................................. 12 
Figure 12 2020 Month-on-month growth and shrinkage ..................................................................................... 12 
Figure 13 Monthly occurrence rates for all operation types ................................................................................. 13 
Figure 14 Monthly occurrence rates for RPT operations ...................................................................................... 13 
Figure 15 Monthly occurrence rates for GA operations ........................................................................................ 13 
Figure 16 2021 Month-on-month growth and shrinkage ..................................................................................... 14 
Figure 17 Overall occurrence rates all types ......................................................................................................... 14 
Figure 18 RPT occurrence rates all types .............................................................................................................. 14 
Figure 19 GA occurrence rates all types ............................................................................................................... 14 
Figure 20 All CFIT occurrence rates each year ...................................................................................................... 15 
Figure 21 RPT CFIT occurrence rates each year .................................................................................................... 15 
Figure 22 GA CFIT occurrence rates each year ..................................................................................................... 15 
Figure 23 GA CFIT month-on-month changes 2020 .............................................................................................. 16 
Figure 24 GA CFIT month-on-month changes 2021 .............................................................................................. 16 
Figure 25 All LOC-I occurrence rates each year .................................................................................................... 16 
Figure 26 RPT LOC-I occurrence rates each year .................................................................................................. 16 
Figure 27 GA LOC-I occurrence rates each year .................................................................................................... 17 
Figure 28 All Runway Incident occurrence rates each year .................................................................................. 17 
Figure 29 RPT Runway Incident occurrence rates each year ................................................................................ 17 
Figure 30 GA Runway Incident occurrence rates each year .................................................................................. 18 
Figure 31 RPT Runway Incidents Month-on-month 2020 ..................................................................................... 18 
Figure 32 RPT Runway Incidents Month-on-month 2021 ..................................................................................... 18 
Figure 33 GA Runway Incidents Month-on-month 2020 ...................................................................................... 19 
Figure 34 GA Runway Incidents Month-on-month 2021 ...................................................................................... 19 
Figure 35 All Landing Incidents occurrence rates each year ................................................................................. 20 
Figure 36 RPT Landing Incidents occurrence rates each year ............................................................................... 20 
Figure 37 GA Landing Incidents occurrence rates each year ................................................................................ 20 
Figure 38 RPT Landing Incidents Month-on-month 2020 ..................................................................................... 21 
Figure 39 RPT Landing Incidents Month-on-month 2021 ..................................................................................... 21 
Figure 40 GA Landing Incidents Month-on-month 2020 ...................................................................................... 21 
Figure 41 GA Landing Incidents Month-on-month 2021 ...................................................................................... 21 
Figure 42 GA VFR into IMC occurrence rates each year........................................................................................ 22 
Figure 43 GA VFR into IMC Month-on-month 2020 .............................................................................................. 22 
Figure 44 GA VFR into IMC Month-on-month 2021 .............................................................................................. 22 
Figure 45 All Separation Issue occurrence rates each year ................................................................................... 23 

AVA80037  Impacts of the Covid-19 Pandemic  Rory Buchanan 
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Human Factors  and Pilot Proficiency 
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Figure 46 RPT Separation Issue occurrence rates each year ................................................................................. 23 
Figure 47 GA Separation Issue occurrence rates each year .................................................................................. 23 
Figure 48 RPT Separation Issues Month-on-month 2020 ..................................................................................... 24 
Figure 49 RPT Separation Issues Month-on-month 2021 ..................................................................................... 24 
Figure 50 GA Separation Issues Month-on-month 2020 ....................................................................................... 24 
Figure 51 GA Separation Issues Month-on-month 2021 ....................................................................................... 24 
Figure 52 Capital city airport movements for each state category ...................................................................... 25 
Figure 53 Overall occurrence rates for Victoria each year .................................................................................... 25 
Figure 54 Overall occurrence rates excluding Victoria each year ......................................................................... 25 
Figure 55 Overall occurrence rates excluding Victoria/NSW each year ................................................................ 26 
Figure 56 Occurrence Rates for Victoria 2020-2021 ............................................................................................. 26 
Figure 57 Occurrence Rates excluding Victoria 2020-2021 .................................................................................. 26 
Figure 58 Occurrence Rates excluding Victoria and NSW 2020-2021................................................................... 27 
Figure 59 Victorian Occurrence Month-on-month 2020 ....................................................................................... 27 
Figure 60 Victorian Occurrence Month-on-month 2021 ....................................................................................... 27 
Figure 61 non-Victorian Occurrence Month-on-month 2020 ............................................................................... 28 
Figure 62 non-Victorian Occurrence Month-on-month 2021 ............................................................................... 28 
Figure 63 non-Victorian/NSW Occurrence Month-on-month 2020 ...................................................................... 28 
Figure 64 non-Victorian/NSW Occurrence Month-on-month 2021 ...................................................................... 28 
Figure 65 ASRS Occurrence rates all types each year ........................................................................................... 29 
Figure 66 ASRS Occurrence types 2020 and 2021 ................................................................................................. 29 
Figure 67 ASRS All types month-on-month changes 2020 .................................................................................... 29 
Figure 68 ASRS All types month-on-month changes 2021 .................................................................................... 29 
Figure 69 Cumulative variation NAOD .................................................................................................................. 31 
Figure 70 Cumulative variation ASRS .................................................................................................................... 31 
Figure 71 NAOD and ASRS overall cumulative variation ...................................................................................... 31 
 

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

Chapter 1 – Introduction

Background

The COVID-19 pandemic brought with it a significant reduction in global aviation activity from mid-

March 2020 that took until the beginning of 2023 to recover to pre-covid levels. As a result, airlines

across the globe – as well as myriad smaller flight operations – began laying-off, furloughing, and

redeploying staff away from the active duties of flight, with many fleets being mothballed at

countless airports due to the dearth of flights. With this reduction in flight activity and large-scale

loss of recency and associated proficiency, what impact can be observed on flight safety events as

recorded in various national databases? Did airlines and general aviation operators successfully

implement strategies to bring crews back to operational readiness as the journey toward normal

operations began? Can we identify areas where, despite intervention to ensure operational

normalcy was made, safety occurrences have been more likely since the return to normal operation?

Relevance – Wasn’t COVID-19 a once off?

While the global impact of the COVID-19 pandemic on the aviation industry was unprecedented,

mass layoffs, furloughs, and extended disruptions in localised portions of the industry are far from

unheard of; notable such events include the post-9/11 downturn in the United States (Simmers,

2006) and the 2010 Icelandic volcano eruption that grounded nearly all flights in Europe (Gill, 2010).

In addition, pandemics are expected in future to occur with greater regularity as climate change

increase the likelihood of transmission of disease from animals to humans (Holmes, 2021)

(Bernstein, n.d.), and so the experiences of COVID-19 can help guide future responses in recovering

from similar disruptions.

Scope

This thesis will utilise occurrence data from Australia and the United States, as available from the

publicly accessible databases maintained by the Australian Transport Safety Bureau (ATSB) and

National Aeronautics and Space Administration (NASA) respectively. These databases are the

National Aviation Occurrence Database (NAOD) and the Aviation Safety Reporting System (ASRS)

respectively.

Chapter 2 – Literature Review

Recent Experience Requirements

It has long been understood that proficiency in skill-based tasks, such as those required in the

operation of an aircraft is highly dependent on both training and recent experience as established by

Ammons et al in 1958. Their study challenged the contemporary view that perceptual-motor skills,

where coordination between sensory inputs and physical response are developed through practice

and experience, were quickly relearned following intervals of non-practise. These skills are utilised in

everything from throwing a ball and playing musical instruments, to driving a car, flying an

aeroplane, or riding a bike. In their research, it was found that instead the time taken to relearn and

return to a similar level of performance to the pre-hiatus level was directly linked to how long of a

hiatus was taken (Ammons et al, 1958). This multi-year study with non-practising intervals of up to

two years determined that pre-hiatus level of proficiency did not reduce the time taken to relearn

skill or to re-establish proficiency, nor did it alter the absolute loss of skill experienced by test

subjects. Proportional loss of skills was greater for those subjects who received less training prior to

their hiatus than for those participants that underwent a greater amount of preparatory training, as

the loss of skill began from a lower point on the performance curve. What this indicates is that the

time to return to service following a hiatus is dependant primarily on the time lapsed during the

hiatus, and less on the skill levels of the individuals affected by the hiatus. Additionally, the findings

of this study can be used to develop return to service training programmes based on the pre-hiatus

levels of experience across cohorts.

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

The undertaking of flight utilises multiple skillsets from flight crews, requiring hand-eye

coordination, instinctual response to various sensory cues, procedural knowledge, and reasoning

based on learned associations experienced through training. In addition, the conduct of a flight

operation involves a choregraphed sequence of events in a fixed order, memory flows and checklists

interspersed with briefings to ensure that all crew have a complete understanding of the

undertakings. This highly complex system is susceptible to lapses, missteps, and misapplications of

steps at the incorrect times should flight crew become slow to act or forgetful of key responses, a

scenario that becomes more likely with breaks from the action. Without recent experience, crews

can begin to experience skill fade affecting not only their manual flying skills (Ebbatson et al, 2010),

but also knowledge of procedures, aircraft systems, memory-based items, and briefings

requirements (CAA, 2021). This skill fade could lead to crews inappropriately responding to

abnormal events, failing to discuss safety relevant information in briefings, and misconfiguring the

aircraft in various stages of flight, all of which would result in reduced safety margins during critical

phases of flight.

This understanding of skill fade is reflected in the regulatory approach of many countries in how

pilots are to maintain the privileges of their licences and ratings, typically with windows in which a

minimum number of flight hours, landings, and approaches must be made. A typical example of

these windows is the International Civil Aviation Organization’s standard that pilots should not

operate an aircraft carrying passengers unless they have completed a minimum of 3 take-offs and

landings in the past 90 days when carrying passengers (ICAO, 2022), a requirement that is reflected

in the regulatory practices of aviation administration globally (FAA, 2022; CASA, 2022a; CAA, 2023).

These requirements, however, can vary dramatically based on the types of operation being

undertaken and the levels of licensing attained by flight crew (SKYbrary, n.d.), with pilots only

required, at a minimum, to fly once with an instructor every two years to maintain the privileges of

their licences (CASA, 2022b). As such, these regulatory requirements should instead only be viewed

as the bare minimum requirements without specific interventions such as recurrent training and

checking.

Further complicating the matter of flight crew performance upon return from hiatus is the possibility

of regulatory or procedural change having occurred during their absence. This may cause crews to

misapply old and no longer in force rules and regulations in the conduct of flights – or fail to conduct

newly implemented operating procedures unique to their operational environment – during periods

of high workload where they may fall back on outdated automatic behaviour. A notable example of

such regulatory change is the effort of CASA in their decades long scheme to bring the Australian air

operating rules into alignment with the United States’ Federal Aviation Regulations (FARs). This

scheme seeks to streamline the regulatory framework of aviation in Australia by bringing disparate

rules and requirements within the fold of a single set of regulations, the Civil Aviation Safety

Regulations (CASRs). Whilst this evolution has been ongoing since 1998, a major milestone was

reached in December 2021 with the implementation of the general flight operating rules (CASA,

n.d.). With this change, new requirements on the conduct of certain operations were introduced as

well as there being a general refinement and simplification of existing rules. Taking place during the

Covid-19 pandemic in Australia, these rules came into effect just as the two largest states in

Australia were emerging from lockdowns that had significantly curtailed aviation. Flight crew

returning to flight in this post-lockdown recovery would thus have to both refamiliarize themselves

with the task of flight operations as well as come to grips with these new rules in certain situations

supplanting established patterns of behaviour.

Another example of changes occurring during a hiatus could be the introduction of new aircraft to an

airline fleet necessitating a change in standard operating procedure to encompass the new aspects

of operation. An airline introducing a variant of an existing aircraft type with different capabilities or

instruments may require that all flight crew on the entire fleet type be retrained, and without the

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

active recent experience some flight crew may struggle to establish the differences sufficiently in

their mental models.

Covid-19 Effect on Flight Recency

With the advent of the Covid-19 pandemic governments across the globe began to implement

border control mechanisms which restricted international travel, then as the virus continued to

spread began to enact domestic restrictions and promulgated advice to minimise travel which

drastically curtailed even domestic air travel. This new reality cut global air traffic down to between

a third of pre-Covid levels for total global aviation movements and a half for commercial and

government flights (Flightradar24.com, 2023).

Figure 1 2019 and 2020 Total ight tracking data

Flightradar24.com

Figure 2 Commercial ight tracking data

Flightradar24.com

With these reductions in air movements airlines across the globe began to rapidly scale back route

offerings, fleet sizes, and staff levels. Sending significant portions of their fleets to mothball storage

and flying skeleton networks, airlines began to furlough and lay-off their workforce – both flight and

ground crews – with approximately half of all commercial flight crew globally left without work in

January of 2021 (Flightglobal.com, 2021), and a third remaining unemployed into 2022 (Whitley,

2022). In addition to commercial airline operations affected by government restrictions, private

operations were often impacted by movement restrictions, not being classified as ‘essential

activities’, meaning that pilots who were not actively engaged in commercial operations that served

a public service had little to no way to maintain their recency obligations (Victoria Government,

2021).

To prevent reduced mobility and public health precautions adversely impacting the efficiency of

aviation operations, regulators began to implement exemptions and extensions to certain recency

and recurrent rules.

In Australia, CASA extended the periods for air traffic services and flight crew personnel for both

flight test intervals and recency obligations (CASA, 2020) whereby license and permit holders who

held permissions as at the first of April 2020 had the validity of those permissions extended by up to

six month so as to minimise the strain on the testing and training system in Australia in view of quite

significant government restrictions and health advice.

In New Zealand, the Civil Aviation Authority (CAANZ) exempted flight crew from the obligation to

undergo the periodic flight proficiency checks and reviews for an additional three months, provided

that they maintain the standard recent experience requirements for those ratings, and that they

held a valid permit that would otherwise expire in the period 15 March 2020 to 24 June 2020

(CAANZ, 2020).

In the United Kingdom, the CAA issued an exemption for the requirement to undertake flight

proficiency checks for certain permits and ratings due to expire between march and October 2020 to

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

extend that validity period to 22 November 2020 after receiving a briefing on abnormal and

emergency procedures, even remotely, from a qualified instructor (CAA, 2020).

In the United States, the FAA similarly provided exemptions of three months to flight review,

proficiency check, and instrument currency requirements between March and September 2020

(FAA, 2020).

This wide-ranging regulatory relief did not, however, tend to affect flight recency provisions relating

to passenger carriage and operational proficiency. What these provisions provided for is that crews

would not be subject to testing and training requirements during the specified periods provided that

they maintained a regular pattern of flying. This meant that as public health advice changed and

restrictions were lifted, there remained a sizeable portion of the aviation sector – particularly in

testing and training – who could immediately move into providing recency regaining services to

other flight crew returning from hiatus, though potentially without significant recent actual

experience beyond regulatory minimums.

These provisions did not, in general, impact those flight crew who had access to flight simulation

devices. Most regulatory authorities provide for alternative means of compliance for operators who

utilise high fidelity flight simulators to maintain recency and other testing and training requirements.

Airlines can ensure that flight crew meet minimum flight recency obligations in a simulator without

flight crew having to operate in a physical aircraft. These simulator sessions, additionally, are also

classified as being part of an airline pilot’s employment and so were often covered by exemptions to

public health orders to minimise social contact. What this meant for the return to service of many

airlines, is that with preparation many services could begin with minimal disruption as restrictions

began to lift.

Existing understandings of how Covid has impacted flight safety

Immediately following the drastic flight reductions associated with the early pandemic, it was

expected that there would be a consequent reduction in inflight deviations and exceedances. This

phenomenon was not consistently the case; indeed, by a number of measures in various locations

and phases of flight, abnormal measures occurred at an elevated rate. At Paris Charles de Gaulle

airport, the number of atypical energy approaches – where the aircraft approaches at inappropriate

speeds and altitudes, often as a result of being vectored to approach from too high or at too high a

speed – increase by around 50 per cent despite a reduction in traffic of approximately 90 per cent

(Jarry et al., 2021).

With this recognised increase in the occurrence of abnormal inflight states, regulators published

reports identifying risk factors to aid in mitigation strategies spurred on by ICAO recommendation

(ICAO, 2020). The European Union Aviation Safety Agency (EASA) published one such report which

demonstrates the complex nature of ascribing causal factors to recognised and potential outcomes

that arose during the pandemic (EASA, 2020). This undertaking by EASA was also updated with a

subsequent version being released ten months later with additional learnings and identified risk

factors (EASA, 2021).

In these reports, the regulator specifically calls out the hazards of skill and knowledge degradation

from lack of recent practice, increased periods between licence and validation checks reducing the

oversight opportunities to catch falling performance, with later addition of recognised hazards of

reduced knowledge transfer for new flight crews that they would otherwise receive through

interaction with existing crews, reduced effectiveness of training and checking procedures due to

the lack of access to flight simulators and actual aircraft, as well as the transfer of crews to new

fleets as airlines restructured and streamlined their diverse fleets to include fewer types, thus

reducing the average. time on type of flight crews. These hazards may all contribute to an increase in

undesired aircraft states and will need to be considered in a study of occurrences arising during the

pandemic.

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

Direction

In this study, publicly accessible data will be examined to determine what impacts, if any, the

disruptions of Covid-19 related slow-downs have had, as well as whether certain sectors or types of

operation have been disproportionately affected. In this area, there has already been some work

utilising both publicly accessible data from the ASRS, as well as airline flight data monitoring analysis,

examining adverse safety outcomes and general exceedances from standard operational criteria. In

directing this study three studies are of particular interest, those of Olaganthan and Amihan (2021),

Choi and Gibson (2022), and Li, et al. (2022).

Olaganathan and Amihan (2021)

Utilising the ASRS database, Olaganathan and Amihan (2021) examined occurrences of Controlled

Flight into Terrain (CFIT), Loss of Control In-flight (LOC-I), and unstabilised approaches in the pre-

pandemic period of July 2019 to February 2020, and the subsequent eight months of March 2020 to

October 2020 after the US declaration of pandemic. To narrow down the occurrences, the

researchers utilised key phrase selection relating to currency, proficiency, Covid, and pandemic, to

make use of crews identifying these factors in their self-reports. In asking whether the ASRS data

indicates a difference in the prevalence of pilot proficiency and skill in ASRS reports between the

pre- and mid-pandemic periods, the study found that there was a tenfold increase in proficiency

related reports related to the Covid-19 pandemic despite a reduction in US flights of approximately

71 per cent.

This finding, however, is based on a small set of occurrences with only a single ASRS report in the

pre-Covid period attributing the incident to proficiency or currency versus ten for the post-

declaration period. Of note is the relative fall of occurrences identified by the study, as despite flight

activity in the period following the Covid pandemic declaration falling to as low as 30 per cent of its

pre-declaration levels, total numbers of reports only fell to 56 per cent and CFIT, LOC-I and unstable

approaches only fell to 62 per cent of their respective pre-declaration levels. This finding indicates

that further examination, perhaps of a larger timescale, may be necessary to better quantify the

effect of the Covid-19 pandemic on flight safety, and whether flight crew proficiency and recency

have continued to present at a higher rate in report attributions.

Choi and Gibson (2022)

Choi and Gibson (2022) similarly utilise the ASRS dataset, however they extended the window of

occurrences from January 2018 through to June 2020, providing a greater number of pre-pandemic

occurrences against which to examine the pandemic period. By limiting the pandemic portion of the

dataset to June of 2020, the researchers were able to focus on the period of greatest disruption in

the United States aviation sector. With the use of machine learning techniques to analyse the

collected data, the study found that the pandemic produced conditions conducive to aircraft

incursions and excursions – identifying situational awareness, distraction, training, and pilot flight

experience as key human factors considerations in the causal sequence for the reported events.

Once again, analysis of the ASRS data showed an increase in the frequency of self-reporting of

incidents despite a reduction of flight activity, highlighting the need to consider the safety impacts

arising from a period of disruption; of which Covid-19 is the most recent, and most dramatic possibly

since the second world war.

Complicating the findings of the study is the identified factor that as the pandemic began to spread,

regulators were quick to act in highlighting possible safety hazards resulting from the pandemic, and

the heightened awareness of crews to the utility of the ASRS in both promoting safety, but also

protecting themselves from regulatory action. This apparent increase in willingness to report may

confound analysis stemming from self-reported occurrences making comparison between pre- and

mid-pandemic datasets unreliable. To counter this, the researchers suggest utilising alternative

datasets, not just the ASRS and not just self-reported data. Self-report and occurrence databases are

limited by their lagging nature, reducing their utility in a predictive hazard reduction system. Timely

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

analysis of causal factors to safety occurrences is highlighted as critical to hazard identification and

mitigation, and so data that is close to real time may be of greater utility in drafting protections

against disruption.

Li et al. (2022)

To consider the effect of the pandemic on flight safety, Li et al. (2022) did not utilise the ASRS or

other open-source dataset, instead being granted access to the flight data monitoring (FDM)

program of an international airline to examine exceedances across flight phases and fleets between

June 2019 to January 2020, February 2020 to September 2020, and October 2020 to May 2021. In

addition to raw FDM data, the study had access to whether air safety reports were submitted by

flight crews, which provide additional narrative to specific FDM event. The study found that while

the pandemic had affected the frequency of FDM categories of occurrences, and the phases of flight

and fleets they occurred within, it had not led to a greater number of safety reports being made by

flight crew – suggesting that pilot proficiency in aircraft handling and procedural control had fallen,

and that crews were failing to recognise these undesired aircraft states when they occurred. Pilot

proficiency was identified as a key factor in the frequency of FDM events, with training focussing on

knowledge of flight deck automation, standard operating procedures and their effects, and manual

flying skill being key focus areas identified for return to service training.

While air safety reports were required to be submitted in the event of a go-around procedure, flight

crews were not obligated to make reports in other situations. What the authors noted was that

where FDM events crossed the threshold for categorisation as a mid-air collision risk crews reported

the occurrences at a much higher rate than runway excursion events, with 53.4 per cent versus 4.3

per cent, with the suggestion that this could be due to flight crews perceiving the relative threats of

differing categories of events at different intensities. This indicates that when utilising datasets

which rely on self-reporting by the involved parties, caution needs to be taken not to assume that

the dataset is complete and to understand that not all occurrence categories will be reported with

the same frequencies.

What now?

It is clear that there was an increase in the rate of flight safety occurrences and reports in the wake

of the Covid-19 induced downturn in flight activity, this is corroborated by the data collected

through automated systems and routine data evaluation. During the pandemic national aviation

authorities, airlines, industry, and advocacy groups have all spent considerable effort on

communicating the potential risks and hazards arising as a result of the loss of proficiency of actors

throughout the aviation system from prolonged absence. This focus on safety may have caused self-

reporting of occurrences to increase, and so when utilising self-reported data having a greater access

to both pre- and post-downturn reports a longer time frame may help to normalise this effect.

Research Questions

This study will seek to answer the following questions:

1. Did the Covid-19 related downturn in aviation activity result in a higher rate of safety

occurrences in Australia?

a. What types of occurrences were most affected by the Covid-19 pandemic?

2. Did the severity of Covid-19 restrictions in Australia result in a greater variation in the rate of

safety occurrences than in the United States?

a. Did the longer lasting and significantly harsher restrictions in Victoria, compared

with the other states and territories, result in a greater change in occurrence rates?

3. Has any variation the level of safety occurrences plateaued at a new level or is the level

similar to the pre-pandemic levels?

AVA80037 Impacts of the Covid-19 Pandemic Rory Buchanan

Aviation Research Dissertation on Flight Safety 101121216

Human Factors and Pilot Proficiency

4. Which sectors of the industry saw the greatest effect of pandemic-related occurrences?

5. To what extent can loss of pilot proficiency from reductions in flight hours explain variations

in occurrence rates?

Chapter 3 – Methodology

Data Sources

To examine the impacts of the COVID-19 pandemic on flight safety occurrences, I will make use of

NAOD and ASRS data. These databases are accessible through online web query and provide for

looking at incidents overall as well as drilling down into the details of specific incidents and

categories of incidents.

ATSB NAOD

The ATSB dataset provides information regarding to occurrences within the territory of Australia,

and for operations by Australian registered aircraft abroad. The types of occurrences that are

recorded in the dataset are those classified as incidents, serious incidents, or accidents with the

meanings defined by the Transport Safety Investigation Regulations 2021. Occurrences that are not

coded as such are not included within the NAOD dataset.

In the NAOD, the categories are: dates, locations, types of operation, types of activity, category of

occurrence (e.g. airspace, environmental, operational, technical), airspace involved, registration

type, aircraft type, phase of flight, damage level, flight conditions, flight rules, class of occurrence,

and injury level.

NASA ASRS

The ASRS dataset provides information regarding occurrences in the United States and is derived

from voluntary reporting of flight safety occurrences by those involved in the incident. These reports

provide those involved with the occurrence with a level of immunity from enforcement action by the

regulator for violations of flight regulations and laws. As such, there is a greater number of reports

that cover a greater scope than the NAOD. Where multiple reports are generated of the same

incident – as may be the case where multiple aircraft are involved and make separate reports, or

where air traffic service personnel make a report that has also been reported by flight crew – the

database combines them into a single overall report with the information compiled. This reduces the

chance of duplicate reporting of events skewing the data.

In the ASRS dataset, occurrences are categorised by: dates, report number, flight conditions, lighting,

weather, type of operation, flight plan type, phase of flight, type of aircraft, mission of flight,

location, type of organisation and position of reporters, type of event, detected by, primary

problem, contributing factors, human factors, and result.

Limitations of Data Sources

Neither of these databases can be viewed as complete and authoritative lists of all aviation safety

relevant occurrences for any period, as called out in the limitations provided by the two authorities.

However, the data can be used to provide evidence of trends and statistical anomalies to understand

the frequency and types of safety occurrences in the two jurisdictions. For each entry in the two

datasets, not all information of each category of search may be present, and so certain occurrences

which may be relevant to the scope of this study may not appear when searches for particular terms

are undertaken but may show up in the larger, less specific datasets. Occurrences in the ASRS

dataset are submitted voluntarily and may exhibit elements of self-reporting bias (ASRS, n.d.), while

NAOD occurrences may be subject to change as data is verified and reports are validated (ATSB,

n.d.).

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Selection of Datasets

The period selected for the collection of safety occurrences is from January 1, 2017 – December 31,

2022. This provides approximately a three-year window for safety occurrences either side of the

drastic reductions in aviation traffic in March 2020 (see figure 1.) and allows for analysis of events

coinciding with the easing of restrictions in Australia and the United States, which continued into

2022. It was decided to use January 1 through December 31 as this allowed for matching annual data

reports with released statistical figures.

NAOD

Pre-Analysis

To determine rates of occurrences, the Bureau of Infrastructure and Transport Research Economics

(BITRE) Australian Aircraft Activity 2021 Statistical Report (BITRE, 2022) was used. This report

includes the annual flight hours of aircraft on the Australian aircraft registry between 2014 – 2021. In

addition to flight hour figures, BITRE also provides total airport movements for Australian airports

(BITRE, n.d.), which allows the estimation of monthly flight hour activity.

Dataset

ATSB provided a set of all occurrences which matched the following criteria in the search tools

provided on the ATSB website:

Year is greater than or equal to 2010

Date is on or after 01/01/17 and is on or before 31/12/22

Occurrence Category Level 1 is Operational

Occurrence Category Level 2 is Aircraft control, Aircraft loading, Communications, Flight

preparation / Navigation, Fuel related, Ground operations, Ground proximity alerts /

warnings, Miscellaneous, Runway events, or Terrain collisions

These criteria were selected to exclude flight events which did not relate to flight crew proficiency,

namely mechanical events, injuries as a result of passenger or crew misadventure, injuries due to

turbulence, and other related types of occurrences. Where these excluded categories occurred in

conjunction with the selected criteria, they will appear in the dataset but no occurrences comprising

just the excluded categories have been included.

Under the search criteria, the dataset contains 9436 occurrences.

Estimated Activity between January 2022 and December 2022

As BITRE has, at the time of this study, not released the annual activity figures for 2022 these figures

were estimated from the Australian Domestic Aviation Activity annual publications published by

BITRE. To do this, the average flight hours per trip was calculated for the domestic fleet from the

2017, 2018, 2019, 2020, and 2021 reports. This average number of hours per trip was multiplied by

the total trip figure from the 2022 report to give an estimate of total flight hours for the commercial

fleet. As the total trips for 2022 were substantially closer to the 2017-2019 average and the 2020-

2021 trips being significantly less than both the pre-covid and 2022 total trips, the average number

of hours per trip was calculated based on the average of pre-covid trip figures and flight hours,

excluding 2020-2021.

To estimate the total fleet flight hours from this estimated commercial flight hours figure, the hours

of commercial and general aviation were compared for the period 2017 – 2021. As the ratio

between general aviation and commercial flights was significantly higher between 2020 and 2021,

these years were excluded from the estimation of the 2022 ratio between general and commercial

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aviation. As the estimated hours per trip and total flying hours of the commercial fleet were still

approximately 20 per cent below pre-covid levels, the average calculated for the

general/commercial ratio was increased by the ratio of the 2022 total trip figures and the average of

the 2017-2019 total trips. Multiplying the estimated commercial fleet hours by this calculated ratio

gave an estimate for general aviation fleet hours, the sum of which gave estimated total fleet hours.

Monthly Activity

To estimate monthly flight hours, the BITRE monthly airport traffic data was utilised to allocate

annual flight hours by the proportion of airport movements. It was decided to estimate the monthly

flight hours in this way, rather than using the movements as the rate basis of analysis, to account for

changes in flying patterns during the Covid period, and to align with established practice of quoting

safety occurrences by flight time or distance rather than the raw number of flights, and to account

for the changing flight characteristics in light of Covid restrictions. It should be noted that when the

annual flight time is compared with the number of movements, the average flight time per

movement in 2020 and 2021 is over an hour longer than pre-Covid; this is might be due to flight

training activity reductions and reductions in short-haul flight operations between Melbourne and

Sydney, formerly the fifth busiest domestic air route globally (OAG, 2020), during those cities’

lockdowns.

Figure 5 Esmated total monthly ight hours, overlaid on

Covid-19 lockdowns and restricons

Figure 6 Esmated monthly ight hours of RPT and GA

eets

As the BITRE airport movements dataset is focussed on airports which see RPT (Regular Public

Transport, interpreted in the BITRE and NAOD data as Commercial Scheduled operations) services,

the estimated proportions of flight hours in the GA fleet exhibit significant variation. However,

despite these variations being quite large (approaching double the pre-covid average flight hours),

they do not appear to significantly alter the calculated rates of occurrences (see results section).

State Breakdowns

To consider the effect of more severe lockdown measures data from occurrences marked as taking

place in Victoria was similarly analysed, utilising Melbourne airport movements from BITRE as the

reference upon which monthly movements were estimated. Melbourne airport is the sole reference,

as in the monthly movement statistics provided by BITRE it is the only Victorian airfield individually

measured. As such it can be expected that the movements are skewed in favour of RPT traffic, so

state occurrence data was measured without regard to the split between RPT and general aviation

traffic.

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Figure 7 Melbourne Airport Movements, with indicaon of Victorian Covid-19 restricons

ASRS

Data for the total fleet flying hours for the United States was not readily available, and so rates of

occurrence were calculated based on numbers of departures from the FAA Aviation System

Performance Metrics (ASPM) airport analysis (FAA, n.d.). As the inclusion of US data is for

comparison of magnitude of occurrence variations with Australian data, these comparisons will be

made with movement data rather than flight hours. The ASPM data contains movement data for a

set of 77 representative airports across the USA. Movements were calculated as the average of

departures and arrivals for each month.

Figure 8 ASPM 77 Airport movements, with WHO covid pandemic and Covid-19 endemic (Achenbach and Pietsch, 2022)

periods overlaid

Dataset

The ASRS database allows for direct downloading of search results based on supplied criteria. To

query the ASRS database, a similar query to the NAOD dataset was utilised:

Date of Incident was between January-2017, December-2022 and Event Type was [Airspace

Violation] All Types, [ATC Issue] All Types, [Conflict] Airborne Conflict, Ground Conflict,

Critical, Ground Conflict, Less Severe, NMAC, [Deviation – Altitude] Crossing Restriction Not

Met, Excursion From Assigned Altitude, Overshoot, Undershoot, [Deviation/Discrepancy –

Procedural] Clearance, FAR, Hazardous Material Violation, Landing Without Clearance,

[Deviation – Speed] All Types, [Deviation – Track/Heading] All Types, [Ground

Event/Encounter] Gear Up Landing, Loss Of Aircraft Control, Ground Strike – Aircraft,

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[Ground Excursion] Ramp, Runway, Taxiway, [Ground Incursion] Ramp, Runway, Taxiway,

[Inflight Event/Encounter] CFTT / CFIT, VFR In IMC, Unstabilized Approach

This query – downloaded in multiple parts due to ASRS limitations – resulted in a dataset containing

20752 entries.

Occurrence Rates

With the conditions set out above, the datasets were analysed to derive occurrence statistics in

rates per thousand hours or movements, as indicated. Overall rates were considered, as well as the

split between GA and RPT occurrences. The categories of CFIT, LOC-I, Runway Excursion (identified

by Li, et al. and Olaganathan and Amihan as key occurrence types) were separated, as were events

identified with “separation”, and hard landing, wheel up, and unstable approach events, to consider

mid-air and ground collision risks, and unstable approach and landing incidents in comparison to the

findings of Li, et al., Olaganathan and Amihan, and Choi and Gibson. Runway incursions and

excursions have been grouped together, in part due to the manner in which the ASRS dataset

classifies such occurrences making it difficult to reliably distinguish between occurrence types, in

keeping with the practise of Choi and Gibson.

To investigate whether the more severe lockdown restrictions resulted in a greater level of

occurrences in Victoria compared with other states the same categories were considered for

occurrences marked as taking place in Victoria, without the distinction of GA and RPT operations due

to the lack of data from GA airports in the BITRE dataset. The metric utilised was number of

movements at Melbourne international airport rather than hours. For comparison occurrence rates

for the states and territories except Victoria were calculated through the same metrics, based on the

major airports of the capital cities of each jurisdiction. Because of the highly centralised nature of

the Australian population distribution, and the significantly higher levels of traffic seen by these

major airports in each jurisdiction compared with other minor airports within the same states and

territories, it is not expected that this will introduce significant error.

Chapter 4 – Results

NAOD Occurrence Rates

Overall

Prior to Covid-19 the overall monthly occurrence rate for Australia varied between 0.3924 and

0.6953 safety occurrences per thousand hours for all operation types. For all three categories – All

occurrences, RPT Occurrences, GA Occurrences – 2020 stands out as a year with a span of monthly

occurrence rates across a greater variation than the preceding years. Monthly occurrence rate in

2020 saw first quartile above the mean of 2017 through 2018 years, and a mean beyond the third

quartiles of those years. Similarly, GA and RPT both saw increases to a similar or greater degree.

Figures 9, 10, and 11 depict the span of monthly occurrence rates for each year.

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Figure 9 All occurrence rates each year

Figure 10 RPT occurrence rates each year

Figure 11 GA occurrence rates each year

As flight hours began to fall in March and April 2020, the rates increased to 0.8101 occurrences per

thousand hours, with the rate falling slightly in May as the reduction in flight hours began to level

out. With the initial recovery of flight hours in June and July, during the period of restriction easing

prior to the reintroduction of restrictions in Victoria in August, total flight hours increased by 26.2%

and 39.2%. During the same period, overall occurrences rose 42.4% and 63.8%, with a consequent

rise of rates by 12.9% and 17.7%. As restrictions were re-implemented in Victoria, occurrences and

occurrence rates fell further than flight hours (26% and 23.7% versus 3%), but as flight hours

increased in September so too did accident rates, with the rate rising by 8.9% as flight hours

increased by 11.2%. Figure 12 shows the month-on-month changes in flight hours, number of

occurrences, and occurrence rates during 2020.

Figure 12 2020 Month-on-month growth and shrinkage

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Figures 13, 14, and 15 respectively depict the monthly occurrence rates per thousand flight hours for

all operation types, RPT operations, and non-RPT operations for each year considered in the dataset.

2020 stands out as a year with elevated occurrence rates between April and October, the period

with the greatest severity of restriction and greatest reduction in overall mobility. Quite apparent is

the significantly higher rate of occurrences for RPT operations reaching an estimated 2.39

occurrences per thousand hours, approximately four time the pre-Covid rate. General aviation rates

peaked approximately two times higher than the pre-Covid average of 0.46 occurrences per

thousand hours at 0.88 per thousand. Similarly overall occurrence rates for all operation types

peaked again just under twice the pre covid average of 0.52 per thousand at 0.94 per thousand. In

each case, the occurrence rate in 2020 peaked in July – as flight hours began their initial recovery

and flight crews began returning to the air as restrictions eased.

Figure 13 Monthly occurrence rates for all operaon types

Figure 14 Monthly occurrence rates for RPT operaons

Figure 15 Monthly occurrence rates for GA operaons

2021 saw similar changes in the occurrence rates as restrictions were implemented, with a spike in

occurrence rates as restrictions were implemented in June across New South Wales and Victoria.

While the reduction in flight hours was not as great as 2020, despite the greater territorial and

population extent of government restrictions, an increase in the rate of occurrences was apparent

with the recovery of flight hours from September through November as restrictions were gradually

eased. Figure 16 shows month-on-month changes in flight hours, number of occurrences, and

occurrence rates during 2021.

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Figure 16 2021 Month-on-month growth and shrinkage

Occurrence Types

The occurrence types for CFIT, LOC-I, Runway Incursion/Excursion, Landing Incidents, VFR into IMC,

and Separation Issues have been broken down into RPT and GA occurrence rates, as well as overall

occurrence rates for all operations. Depicted are the occurrence rates for each of these types of

occurrences for 2020 and 2021 – the years impacted by lockdowns in Australia – for each of all

operation types (Figure 17), RPT (Figure 18), and GA (Figure 19). Within each grouping runway

incidents – incursions and excursions

Figure 17 Overall occurrence rates all types

Figure 18 RPT occurrence rates all types

Figure 19 GA occurrence rates all types

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CFIT

In the period under consideration, general aviation has been responsible for the majority of CFIT

occurrences. Of the 585 CFIT occurrences in the 38 months prior to Covid, only 31 were under RPT

operations. From 2020 through 2022, 31 of the 503 occurrences were RPT. As such, small variations

in the number of RPT CFIT events has the potential to greatly alter the rate, as can a reduction in

flight hours. While 2020 appears as a period with a much greater rate than previous and subsequent

years, the monthly average incidence fell from 0.86 occurrences per month across the period 2017

through 2019 to 0.42 occurrences per month in 2020 (Figure 22).

General Aviation CFIT rates saw a fall in the monthly average occurrence rate in 2020 compared to

previous years but saw a greater spread of rates. The maximum rate of 0.16 per thousand hours

exceeded the 2019 maximum of 0.15 per thousand hours, while the mean fell below the 25th

percentile of the previous three years.

Figure 20 All CFIT occurrence rates each year

Figure 21 RPT CFIT occurrence rates each year

Figure 22 GA CFIT occurrence rates each year

Similar to overall occurrences, the GA CFIT rate in 2020 saw occurrences and rates rise in line with

increases in flight hours following the easing of Covid restrictions in June, September, and November

(Figure 23). This trend of increasing rates of occurrences alongside flight hour recovery did not

continue across multiple months unlike as was seen in overall occurrence rates. Occurrence rates in

2021 increased along with flight hours in March and November, months in which lockdown

restrictions eased, while all reductions in flight hours were accompanied by spikes in occurrence

rates (Figure 24).

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Figure 23 GA CFIT month-on-month changes 2020

Figure 24 GA CFIT month-on-month changes 2021

LOC-I

Inflight loss of control is highly uncommon in RPT operations (Figure 26). As such the overall

occurrence rate effectively tracks the rate of GA occurrences, albeit generally at a lower level. In

2020 however overall occurrences exhibit a much greater spread in monthly occurrence rates than

GA due to July and October each having a single RPT occurrence which at the significantly reduced

flight hours resulted in rates of 0.08 and 0.07 per thousand hours respectively for RPT

disproportionately impacting overall occurrence rates (Figure 26). For GA, LOC-I events saw a

reduction in 2020 compared to the three previous years, followed by an increase in 2021 (Figure 27).

The pre-Covid downward trend in LOC-I, apparent in the decreasing means of monthly rates (Figures

25, 27) exhibited a reversal in 2020 and 2021, however rates again began to fall in 2022.

Figure 25 All LOC-I occurrence rates each year

Figure 26 RPT LOC-I occurrence rates each year

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Runway Incursion/Excursion

Prior to 2020, the monthly mean occurrence of runway incursions and excursions was relatively

stable between 0.0897 and 0.1014 occurrences per thousand hours. In 2020 mean monthly rates of

occurrence rose to 0.1288 occurrences per thousand hours (Figure 28). RPT saw the greatest

increase in mean monthly rates rising to 0.2009 occurrences per thousand hours from pre-covid

rates between 0.0386 and 0.0657 occurrences per thousand hours with rates rising as high as 0.5524

in April following the onset of restrictions (Figure 29). GA saw a small rise in the monthly mean in

2020 above the pre-Covid levels with 75 per cent of monthly occurrence rates above the 2019 mean

monthly rate (Figure 30). After 2020, overall operation types saw a year on year decrease in both

2021 and 2022 with mean occurrence rates falling well below both 2020 and pre-Covid levels, as did

GA operations. RPT returned to levels similar to pre-Covid occurrences as total flight hours began to

return to pre-Covid levels.

Figure 28 All Runway Incident occurrence rates each year

Figure 29 RPT Runway Incident occurrence rates each year

Figure 27 GA LOC-I occurrence rates each year

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Figure 30 GA Runway Incident occurrence rates each year

Considering the effect of changing flight hours in 2020, RPT saw increases in occurrence rates in

March, June, and November alongside increases in flight hours (Figure 31). In the same period GA

saw rate increases in July and September with increases in flight hours (Figure 33). Both RPT and GA

saw hourly increases in six of the seven months following the initial reduction in hours of April 2020,

and in each case, the month on month rise of rates was followed by a subsequent fall. In 2021, RPT

incident rates increased alongside flight hours in three of seven months which saw hourly increases

(Figure 32), while GA saw rate increases in four of seven months which saw hourly increases (Figure

34). Where flight hour increases followed a period of restrictions – namely June, July, and

September, October, November in 2020, and September through December 2021 being when

lockdown conditions were lifted in Victoria and New South Wales – four out of nine months for RPT

saw an increase in occurrence rates, while over the same period GA similarly saw increases in four of

nine months, while also seeing increases in occurrence rates in April and May of 2021, consequent

with the implementation and easing of snap lockdown periods.

Figure 31 RPT Runway Incidents Month-on-month 2020

Figure 32 RPT Runway Incidents Month-on-month 2021

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Figure 33 GA Runway Incidents Month-on-month 2020

Figure 34 GA Runway Incidents Month-on-month 2021

Landing Incidents

Prior to 2020, monthly occurrence rates for landing incidents – wheels up landings, hard landings,

and unstabilised approaches – varied between 0.01 and 0.05 occurrences per thousand hours,

excepting July 2017 which saw no such occurrences, with a mean monthly occurrence rate in the

pre-Covid period of 0.0286 (Figure 35). 2020 saw a slight fall in the mean monthly rate to 0.0246

occurrences per thousand hours, or 0.0207 per thousand hours from April. 2021 recorded a rise in

the mean monthly occurrence rate to 0.0257 occurrences per thousand hours, though with a lower

maximum monthly occurrence rate than previous years. 2022 saw another fall in mean monthly

occurrences to 0.0220 occurrences per thousand hours with, with a maximum rate of 0.0464 –

highest since November 2019. General aviation (Figure 37) operations saw a drop in the rate of

landing incident occurrences, with significantly less variation in monthly occurrence than prior years

with a span of 0.0376 occurrences per thousand hours between the maximum and minimum rates

compared to the spans of 2017, 2018, and 2019 of 0.0917, 0.0723, and 0.0619 occurrences per

thousand respectively.

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Figure 35 All Landing Incidents occurrence rates each year

Figure 36 RPT Landing Incidents occurrence rates each

year

Figure 37 GA Landing Incidents occurrence rates each year

Considering the monthly landing incident changes for RPT operations is complicated by the number

of months which saw zero occurrences of landing incidents resulting in indefinite percentage

increases whenever such an incident occurs. In 2020 October and December saw such increases

(Figure 38), while in 2021 June, and December were months seeing an increase from zero

occurrences the previous month (Figure 39). The rate increases for RPT in 2020 accompanied an

increase in flight hours in three of five rate increases. In 2021, of the three increases in occurrence

rates two were accompanied with flight hour increases.

Analysis of GA occurrences is more straightforward as in the 24-month period from January 2020 to

December 2021, only one month saw no landing incidents – August 2021. In 2020 half of rate

increases accompanied rises in flight hours, in June and September which coincided with the easing

of restrictions Australia-wide in June, and Victoria in September (Figure 40). 2021 saw rate rises

alongside increases in flight hours in March, September, and October which coincide with the

implementation and easing of the early-2021 snap-lockdowns, and the easing of lockdowns in

Victoria and New South Wales (Figure 41). With the imposition of lockdowns in the middle of 2021

both flight hours and occurrence rates fell in concert. Further rises in flight hours beyond the initial

easing of restrictions in November and December saw a reduction in both the number of

occurrences each month and the rate of occurrences.

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Figure 38 RPT Landing Incidents Month-on-month 2020

Figure 39 RPT Landing Incidents Month-on-month 2021

Figure 40 GA Landing Incidents Month-on-month 2020

Figure 41 GA Landing Incidents Month-on-month 2021

VFR into IMC

RPT operations rarely experience VFR into IMC occurrences due to most commercial scheduled

operations being conducted under the instrument flight rules. As such, there were only eight

instances of commercial scheduled VFR into IMC occurrences in the period 2017 to 2022, one of

which occurred in 2020, with none in 2021. With so few instances of VFR into IMC occurrences, it is

not possible to draw meaningful conclusions for RPT occurrences. General Aviation encounters VFR

into IMC with a higher regularity, with 45 occurrences between 2017 and 2022, with a pre-Covid

mean monthly occurrence rate of 0.0068 occurrences per thousand hours. 2020 and 2021 both saw

a reduction in the incidence rate compared to pre-Covid, falling to 0.0052 and 0.0031 occurrences

per thousand respectively. Pre-covid monthly occurrences of VFR into IMC tended to occur with

greatest frequency between April and October, particularly in June, July, and August. The longest

lockdown periods in 2020 and 2021 coincided with these periods with higher average occurrences,

resulting in a lower average occurrence rate for the year.

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Figure 42 GA VFR into IMC occurrence rates each year

In 2020 half of all months saw zero VFR into IMC occurrences, and of the other six months four with

flight hour increases were matched with increases in flight hours. Overall, four of seven months with

increases in flight hours saw increases in occurrence rates of VFR into IMC (Figure 43). In 2021 there

were no occurrences of VFR into IMC between May and October, with all occurrences taking place

between January and April, and once in November (Figure 44). Flight hour increases did not match

significantly with increases in rates of occurrence. 2020 and 2021 both saw reductions in the total

number of VFR into IMC occurrences compared to both pre- and post-Covid levels, alongside

reductions in the rate.

Figure 43 GA VFR into IMC Month-on-month 2020

Figure 44 GA VFR into IMC Month-on-month 2021

Separation Issues

Compared with pre-Covid levels, 2020 and 2021 saw a rise in the mean monthly occurrence of

separation issues, with a greater variation in the inter-month rates of occurrences (Figure 45). This is

most apparent in the incidence of separation issues in RPT operations, with occurrence rates

spanning a range of between 0.0073 and 0.3699 per thousand across the months of 2020 –

excepting the five months which saw zero such occurrences – with three quarters of monthly

occurrences being between 0 and 0.1001 per thousand, while two months (September and

November) are significantly beyond the other months at 0.3699 and 0.2909 occurrences per

thousand respectively (Figure 46). General aviation, unlike RPT, rarely sees months without

occurrences with only three such months between January 2017 and December 2022. 2020 saw an

increase in the mean monthly occurrence value of 2019, but which was still below the 2017 mean

value. Similar to RPT, GA saw two months with excursions well outside the expected span of monthly

occurrence values, with May and September being the months seeing rates of 0.0723 and 0.0611

per thousand hours respectively. Despite these outliers, 2020 saw less variation in the span of

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monthly occurrences than prior years, while 2021 saw a similar mean value of monthly occurrences

as 2020 with a greater span in the monthly rates between 0.0081 and 0.0433 occurrences per

thousand hours (Figure 47).

Figure 45 All Separaon Issue occurrence rates each year

Figure 46 RPT Separaon Issue occurrence rates each year

Figure 47 GA Separaon Issue occurrence rates each year

In 2020 increases in RPT occurrences of separation events were accompanied by increases in flight

hours in three of four months, while eight months overall saw increases in flight hours – four with

consequent falls in occurrence rates (Figure 48). 2021 saw four rate increases alongside flight hour

increases – half of all periods of hour increases. These rises in April, September, November, and

December all coincide with the easing of lockdown restrictions and subsequent increases in

population mobility (Figure 49). General aviation operations in 2020 only saw two months where a

rise in flight hours accompanied a rise in occurrences, at the tail end of the year as restrictions in

Victoria began to ease in September and November. Of the remaining six months which saw flight

hour increases, each month saw an accompanying fall in flight hours, while the remaining four

months each saw falls in monthly flight hours alongside a rise in occurrence rates (Figure 50). In

2021, three months with a rise in flight hours saw a rise in occurrence rates of seven such months.

The other five months of the year saw falls in occurrence rates in June and July, while three other

months saw spikes in occurrence with falls in flight hours in January and August, with February

seeing a fall in the number of occurrences with very little change in flight hours (Figure 51).

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Figure 48 RPT Separaon Issues Month-on-month 2020

Figure 49 RPT Separaon Issues Month-on-month 2021

Figure 50 GA Separaon Issues Month-on-month 2020

Figure 51 GA Separaon Issues Month-on-month 2021

States

2020 saw aircraft movements decline dramatically with the imposition of Covid-19 restrictions by

the various state jurisdictions across Australia (Figure 52). The number of movements at Melbourne

airport fell from 20441 in January 2020 to 2202 in April that year. It wasn’t until April 2021 that

monthly movements rose above 10000, with both April and May 2021 seeing approximately 13500

movements each before again failing to between 2994 and 7154 movements from June to

November that year, reaching 12214 in December 2021. During the period from April to November

2020 where Victoria saw little increase in airport movements, the total movements at the various

capital city airports around Australia apart from Victoria experienced a consistent rise from their low

point of 8819 in April to 21565 in November, recovery to 42% of the pre-covid level of 50772

movements in March. In 2021 movement figures dropped for each category in February, as various

jurisdictions implemented snap lockdowns over the summer months. Prior to the reimplementation

of lockdowns in Victoria and NSW in June and July of 2021, movements reached a peak for all

categories in May 2021. The non-Victorian jurisdictions each saw an uninterrupted fall in movements

from June to their nadir in September, while Victoria experienced a brief pause in the fall between

June and July before bottoming out. By December 2021, each jurisdiction had recovered to a level

greater than the year had begun with the rapid easing of lockdowns beginning in November.

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Figure 52 Capital city airport movements for each state category

With the drastic fall in aircraft movements, 2020 saw spikes in occurrence rates for each category

under consideration. The Victorian mean monthly occurrence rate saw rates rise by 3.3 times from

1.1591, 1.2041, and 1.2503 in 2017, 2018, and 2019, respectively, to 3.9848 occurrences per 1000

movements (Figure 53). Non-Victorian rates rose 2.9 times from 1.8734, 1.9824, and 2.0782 to

5.6910 occurrences per 1000 movements (Figure 54), while excluding NSW occurrences and

movements saw a rise by 2.8 times from 2.2092, 2.3441, and 2.5449 to 6.5465 occurrences per 1000

movements (Figure 55). For each category, rates fell for both 2021 and 2022, with 2021 remaining

above the pre-Covid mean and 2022 returning to, or falling below, pre-Covid levels. In 2021,

Victorian mean monthly occurrences fell to 2.2522 occurrences per 1000 movements, 56.5 per cent

of the 2020 level, while non-Victorian and non-Victorian/NSW occurrences fell to 3.1671 (55.7%) and

3.2523 (49.7%), respectively.

Figure 53 Overall occurrence rates for Victoria each year

Figure 54 Overall occurrence rates excluding Victoria each year

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Figure 55 Overall occurrence rates excluding Victoria/NSW each year

Amongst the categories of investigated occurrence rates, each of the various jurisdictions saw the

greatest impact to Runway Incidents, with spikes in 2020 corresponding to implementation of Covid-

19 restrictions. Victoria saw a subsequent rise in the rates of runway incidents in September and

November 2020 before returning and remaining near to pre-Covid levels throughout 2021. For the

other occurrence rates. Whereas Victoria saw a rapid return in its occurrence rates after brief

periods of significantly elevated rates during and subsequent to Covid-19 restrictions (Figure 56), the

non-Victorian Jurisdictions saw a much more gradual return to lower rates over a period of

approximately eight months (Figures 57, 58). Excluding New South Wales from the other non-

Victorian jurisdictions sees rates remain, while elevated above pre-Covid levels, at a relatively

consistent level (Figure 58) – indicative of the impact that lockdowns have on underlying occurrence

rates. It can be seen that in the non-Victorian dataset including New South Wales there is a rise in

occurrence rates in line with the introduction of lockdown restrictions in Sydney, and later NSW as a

whole through June and July 2021 (Figure 57). Each jurisdictional set considered exhibits an overall

downward trend through the period 2020-2021 when lockdown periods are excluded.

Figure 56 Occurrence Rates for Victoria 2020-2021

Figure 57 Occurrence Rates excluding Victoria 2020-2021

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Figure 58 Occurrence Rates excluding Victoria and NSW 2020-2021

Considering month-on-month changes in the rates of occurrences, Victoria saw an increase in the

rates of occurrences in May with a slight increase in flight activity, followed by a fall in June as

movements increased by nearly a quarter. The next rise in movements, in September 2020, was

accompanied by more than 25 per cent increase in occurrence rate, with further rises in movements

and occurrence rate until December saw a significant rise in flight activity with a fall in occurrence

rates (Figure 59). 2021 saw increases in the rates of occurrence alongside increases in movements in

April and October, while January and June both saw falls in flight activity while experiencing

increases in the number of occurrences (figure 60). Across 2020 and 2021, only March and

December 2021 saw an increase in the number of occurrences alongside a fall in occurrence rates –

where December saw activity increasing more than 120 per cent month-on-month.

Figure 59 Victorian Occurrence Month-on-month 2020

Figure 60 Victorian Occurrence Month-on-month 2021

Occurrences in the various states apart from Victoria saw flight activity increases alongside rises in

rates of occurrence in June, July, and September 2020 – during the initial recovery post early

restrictions easing, and during the period that interstate flights between Victoria and the other

states began to increase (figure 61). 2021 saw four consecutive months of activity increases

alongside falls in occurrences and rates from February to May, while September, October, and

November saw flight hours rise with increases in both occurrences and rates (Figure 61). In both

2020 and 2021 non-Victorian month-on-month changes are smaller in magnitude than experienced

by Victoria

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Figure 61 non-Victorian Occurrence Month-on-month 2020

Figure 62 non-Victorian Occurrence Month-on-month 2021

With the impact of the 2021 lockdown in Sydney and New South Wales, month-on-month figures for

non-Victorian occurrences excluding NSW occurrences without Sydney aircraft movements were

also computed. Without NSW the 2020 figures follow the same trends as with NSW, with August

recording a slight increase in flight hours compared with a slight decrease, and November recording

a slight rise in occurrences compared with 2020’s slight decrease (Figure 63). 2021, however, sees an

inversion of flight hours and occurrence growths (Figure 64); an overall reduction in occurrences in

March, an approximate 10 per cent fall in occurrence rates in July rather than a slight rise, a fall in

occurrence rates in October rather than a rise, significantly greater occurrence rates in November –

above 50 per cent growth rather than approximately 10 per cent – and a fall in overall occurrences in

December.

Figure 63 non-Victorian/NSW Occurrence Month-on-month 2020

Figure 64 non-Victorian/NSW Occurrence Month-on-month 2021

ASRS Occurrence Rates

The NASA ASRS dataset is a self-reporting system, including not just flight safety occurrences, but

also reporting of identified hazards and potentials for adverse outcomes. Despite this, the

taxonomical categorisation of dataset entries is similar to the NAOD dataset. Between 2017 and

2019, the mean monthly occurrence rate in the ASRS collection rose from 0.3956 occurrences per

1000 movements in 2017, 0.4247 in 2018, to 0.4352 occurrences per thousand movements in 2019.

In 2020, the mean monthly occurrence rate rose 1.5 times to 0.6236 occurrences per 1000

movements above the pre-Covid average, with a subsequent fall once again in line with the pre-

Covid trend to 0.5145 in 2021, and 0.5537 in 2022 (Figure 65).

The various category types considered for the ASRS dataset also saw variation resulting from the

Covid-19 disruption. As seen in Australia, runway incidents saw the greatest increase, rising from

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0.0159 occurrences per thousand movements in January 2020 to 0.1816 per thousand by June 2020.

Landing incidents also saw a spike from 0.0202 to 0.0738 between January and July. For all the

various occurrence categories, mean monthly occurrence rates returned to the pre-Covid levels and

re-established pre-Covid trends by the end of 2021, as flight activity in the US began its path toward

recovery (Figure 66).

Figure 65 ASRS Occurrence rates all types each year

Figure 66 ASRS Occurrence types 2020 and 2021

When considering the month-on-month changes of occurrences in the United States, after the initial

disruption period between april and June 2020 – as aircraft movements fell dramatcially before

rebounding – there are very few excursions beyond 10 per cent growth or shrink: only December

2020, March 2021, and June 2021 exhibit such changes following July 2020 (Figure 67, 68). With

most coronavirus restrictions easing before the end of 2020, and with international borders

reopening by mid-2021, flight activity in the United States recovered relatively quickly compared

with australia, and without additional lockdowns, flight activity exhibits a much more orderly

growth, and so minor variations in occurrence numbers do not result in exacerbated changes in

rates.

Figure 67 ASRS All types month-on-month changes 2020

Figure 68 ASRS All types month-on-month changes 2021

While occurrence rates in the ASRS dataset remain at an elevated level post-Covid, it should be

noted that the pre-Covid trend was an increase year-on-year of occurrence reports per thousand

movements. The elevated level post-Covid is along the trend expected from pre-Covid rates of

occurrences.

Comparison with Australian Occurrence Rates

The 50 per cent increase seen by the United States in mean monthly occurrence rates was greater

than the 26 per cent increase in the Australian data. Monthly minimum occurrence rate in the US fell

2.4 per cent in 2020 from the pre-Covid average, while Australia saw an 18.5 per cent reduction. The

monthly maximum occurrence rate rose 100.4 per cent in 2020 above the pre-Covid average in the

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US, compared with a 43 per cent increase in Australia. In 2021 and 2022, the minimum monthly

occurrence rates in the US were both 51 per cent above pre-Covid levels, while the maximum

monthly occurrence rates were 34 and 37 per cent above pre-Covid levels. Australian occurrence

rates in 2021 and 2022 saw minimum occurrence rates remain below pre-Covid averages, 19 per

cent below in 2021 and 31 per cent in 2022 (although excluding December, which has an unusually

low occurrence rate, sees the minimum monthly occurrence rate only 10 per cent below the pre-

Covid average), while the maximum monthly occurrence rates rose 18 per cent and 8 per cent

respectively above pre-Covid averages.

Comparing the magnitude of flight activity changes, the US the greatest month-on-month fall in

flight activity was a fall of 64 per cent in flight movements between March and April 2020, falling 70

per cent year-on-year in May 2020. After the initial reduction in activity, the movement data shows

consistent growth in movements through 2020. In Australia, April saw an 80 per cent fall in month-

on-month flight movements, with May seeing an 85 per cent fall year-on-year. With the falls in flight

activity, the US saw occurrence rates increase by 92 per cent in April with another 57 per cent the

following month, while Australia saw only 82 per cent increase in April, despite a greater fall in

movement activity, with a subsequent fall in occurrence rates in May 2020 of 12 per cent despite

continued activity falls.

Trends

Figures 69 and 70 depict the sum of accumulated variation from the calculated pre-Covid monthly

averages for each type of occurrence category. The magnitude of change in these charts does not

carry significant meaning, however the gradient of the plot is indicative of whether trends remain

elevated above pre-Covid levels, whether they have returned to pre-Covid levels, or have gone

below the pre-Covid rates. Where the line exhibits a positive gradient, this indicates that rates for

that period are elevated above pre-Covid levels, whereas a near-zero gradient indicates that

occurrence rates are nearer the pre-Covid level, and a negative gradient indicates occurrences at a

lower rate than pre-Covid.

In the NAOD dataset (Figure 69), CFIT occurrences have exhibited a rate above the pre-Covid

average since the onset of the pandemic, while landing incidents have consistently exhibited a rate

of occurrences below the pre-Covid average. Runway Incidents saw initially a spike in occurrence

rates, with a reversal in October 2020, after which rates returned to a level below the pre-Covid

average. VFR-into-IMC saw no long-term variation in occurrence rates. Both LOC-I and Separation

occurrences saw an initial rise in occurrence rates above pre-Covid, and each have plateaued near

the pre-Covid average since early 2022.

In the ASRS dataset (Figure 70), CFIT occurrence have seen the same consistent positive variation

above pre-Covid average since the onset of the pandemic. Unlike the NAOD data, runway incidents

did not see a negative variance compared to pre-Covid levels, instead merely returning to near-zero

variation. Landing incidents, like in the NAOD data, saw consistent variances below the pre-Covid

levels, although saw a greater degree of initial increase between May and September 2020, while

separation issues have relatively consistently fallen below pre-Covid rates. VFR-into-IMC, like in the

NAOD data, saw little variation in rate between 2020 and 2021, although began to reduce below the

pre-Covid levels in 2022. Unlike what was seen in Australia, however, the rate of LOC-I occurrences

in the dataset has seen a consistent rise in the cumulative variation above pre-Covid levels,

indicating that these events have been increasing in frequency since the onset of the Covid-19

pandemic.

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Figure 69 Cumulave variaon NAOD

Figure 70 Cumulave variaon ASRS

When considering overall occurrence rates (Figure 71), the NAOD data shows that after the initial

rise in occurrence rate variation between February and October 2020, levels returned to near the

pre-Covid monthly averages between October 2021 and September 2021, before beginning to fall

below pre-Covid levels after September 2021. The ASRS dataset, however, shows a consistent rise

above the pre-Covid levels between February 2020 and December 2022, with a brief return to pre-

Covid levels of occurrence between June and November 2021.

Figure 71 NAOD and ASRS overall cumulave variaon

Chapter 6 – Discussion

Did the Covid-19 related downturn in aviation activity result in a higher rate of

safety occurrences in Australia?

2020 saw a significant increase in the rate of overall occurrences across all types of operation. RPT

operations saw the greatest increase in overall occurrence rates, rising up to four times the pre-

Covid rates. In 2021 lockdown implementation saw increases in the occurrence rates, although to a

much lesser extent as flight hours in 2021 fell to a lower extent than in the initial restrictions period

of 2020. Occurrence rates did not solely increase as a result of flight safety occurrences lagging flight

hour reductions, but also saw increases in instances where flight hours increased, while multiple

monthly periods saw reductions in both flight hours and occurrence rates. Despite lockdowns

continuing into 2021, these saw less of an impact on overall occurrence rates as total flight hours fell

more in proportion with total numbers of occurrences.

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What types of occurrences were most affected by the Covid-19 pandemic?

The Covid-19 pandemic saw occurrence rates rise for CFIT, LOC-I, runway incidents, and separation

issues, while landing incident rates fell during the 2020/2021 period. The greatest increase was in

runway incidents, with an extra 0.0977 occurrences per thousand above pre-Covid levels in May

2020, while CFIT rose 0.0720 in June. For RPT operations, as with overall operations, runway

incidents, with spikes in April and June 2020 above pre-Covid levels, saw the greatest increase,

followed by separation issues peaked in September and November 2020 to a slightly lower level. The

greatest impact for general aviation occurrences was in CFIT rates, with occurrences spiking in

August 2021. General aviation was notable as seeing runway incidents fall significantly through 2021

and 2022 after having seen the greatest increase above pre-Covid levels amongst occurrence types

between May and June 2020.

2022 saw occurrence rates return to levels near the pre-Covid level, except for runway incidents

which consistently remained below pre-Covid levels in the period after. This is notable as it indicates

that the conditions seen within the pandemic period, namely disruption to operational procedures,

stress, unfamiliar procedures due to staffing limits, and lack of recent experience did not produce

significant long-term impact.

Did the severity of Covid-19 restrictions in Australia result in a greater variation

in the rate of safety occurrences than in the United States?

The United States saw a much higher increase in both its mean monthly occurrence rate in 2020

compared with previous years than was seen in the Australian data, however by August this

variation had settled down, with few large changes in month-on-month occurrence numbers or

occurrence rates. While Australia saw a smaller change in magnitude than the US, occurrence rates

and raw occurrence figures continued to experience significant fluctuations into 2022 as various

cities and states entered and left lockdown restrictions. Despite its increase in occurrence rates, the

United States only saw a 63 per cent reduction in flight activity compared to Australia’s 81 per cent.

As the United States occurrence data was based on voluntarily reported incidents and hazardous

situations, this may indicate that the messaging from the various regulatory authorities on the

identified risks during the early Covid period was reaching personnel with high effectiveness,

encouraging the reporting of identified hazards at an elevated rate. The later leveling out of monthly

occurrence figure from August onwards may indicate that after the initial period willingness to

proactively report identified risks, flight operation personnel may have returned to previous

reporting hazards, only reporting more serious incidents as the initial disruption period gave way to

familiarity with the new normal later in the year and throughout 2021.

Did the longer lasting and significantly harsher restrictions in Victoria,

compared with the other states and territories, result in a greater change in

occurrence rates?

The severity of the lockdown restrictions in Victoria saw mean monthly occurrence rates increase 3.3

times above pre-Covid levels in 2020, while in the same period the non-Victorian occurrence rates

rose by a factor of 2.9. During the periods of 2020 and early 2021 where lockdowns were eased in

Victoria, rates remained at a greater level than the other states and territories. Coming into 2021,

non-Victorian occurrences rose with the introduction of lockdown restrictions in Sydney and New

South Wales, however remained consistent when excluding New South Wales occurrences and

airport movements.

While Victoria saw greater increases in occurrence rates during periods of lockdown, each

subsequent period of restrictions saw a diminished impact, a trend which was apparent within other

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jurisdictions. This may be due to the reduction in the levels of lockdown compliance amongst the

populations of various states with consequently smaller falls in flight activity levels meaning fewer

flight crews taking breaks from flying with lower losses of flight crew proficiency.

Has any variation the level of safety occurrences plateaued at a new level or is

the level similar to the pre-pandemic levels?

In Australia, overall occurrence rates have returned to below the pre-Covid levels since early 2022.

Before October 2021 the overall rates in Australia saw consistent occurrence rates above the pre-

Covid average level, however after that point, the occurrence rates returned to levels similar to pre-

Covid levels. Of specific occurrence types, CFIT occurrences in Australia have seen occurrence rates

at a higher level than pre-Covid averages, while LOC-I, VFR-into-IMC, and Separation Issues have

returned to pre-Covid levels, and Landing Incidents and Runway Incidents have fallen below the pre-

Covid levels consistently since late October.

Conversely, the trend seen in the United States data is that occurrence rates have remained

elevated above the pre-Covid average, with a brief return to pre-Covid levels between June and

November 2021, with another return briefly toward the end of 2022. This may indicate that

occurrences were unusually low in the ASRS dataset prior to the period under consideration with the

new rate being closer to the overall trend pre-Covid disruption. Additionally, as the ASRS data is

based on voluntary reporting, it may be expected that in normal operation as flight hours increase

that reporting rates would also increase, with this factor requiring average occurrence rates be

calculated on not just monthly occurrence rates but also factoring the varying levels of flight activity

and communication surrounding the message of the voluntary reporting system, a calculation that is

beyond the scope of this study.

Which sectors of the industry saw the greatest effect of pandemic-related

occurrences?

RPT saw significant variation in occurrence rates, although with low variation in raw occurrence

numbers. This may indicate that the rate variations were primarily affected by significant flight

activity reductions while potentially still servicing areas with higher risk profiles at similar levels than

pre-Covid operations. As RPT operational levels began to increase, flight safety occurrences saw

modest increases immediately following lockdown periods, an effect which dissipated within one or

two months typically. General aviation activities saw less of an initial spike in occurrence rates early

on in the pandemic, instead rising more significantly during the greater restriction periods between

June and September 2020, and through mid to late 2021. In each case, as with RPT, the periods

subsequent to lockdowns saw some increases in occurrence rates, which took longer to dissipate

than in RPT operations.

The greatest variation in occurrence rates was within RPT operations, with their four-fold increase,

however these exhibited a strong downward trend back to pre-Covid levels throughout 2020 and

2021, while general aviation activity saw rates remain elevated for a longer period with a more

gradual reduction in rates during the same window.

To what extent can loss of pilot proficiency from reductions in flight hours

explain variations in occurrence rates?

The initial spikes in occurrence rates can be seen as more a consequence of significant falls in flight

activity with factors external to operations, such as stress and uncertainty, potentially impacting

pilot performance. However, as flight activity began to recover at multiple stages occurrence rates

increased alongside flight activity levels, notably at points when coronavirus restrictions were being

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lifted – indicative of possible pilot proficiency issues during the return to service from standdown in

RPT service, and from periods of inactivity for GA operators.

RPT operations initially saw a large spike in occurrence rates during the initial stage of the pandemic,

after which the rate trended back downward as flight activity once again began to rise, with brief

reversals as new lockdown restrictions began to take effect in July 2020 and June 2021. This

contrasts with GA operations, which saw rate slight increases in late 2020 and 2021 during the

periods where lockdown restrictions were easing.

Both RPT and GA activity saw significant growth during the later months of both these years,

however it may be that RPT operations were able to avoid consequent rises in occurrence rates

through the use of organisational training and checking – keeping in mind that most RPT operations

involve multiple flight crew members – compared with the self-directed proficiency checking more

prevalent in GA operations, which more commonly operate with solo flight crew in routine

operations.

Loss of control incidents often have multiple factors combine to result in a safety occurrence, with

flight crew errors commonly having the potential to compound initial upsets into more serious

undesired outcomes (IATA, 2019). With lockdowns and related flight activity downturns the

potential for flight crew to lose proficiency is apparent. During between September 2020 and

January 2021, general aviation activity saw LOC-I occurrences rise above pre-Covid levels as flight

activity began to recover, remaining elevated until May 2021. This rise in occurrence rates as

lockdowns eased and pilots began returning to the air may indicate a causal link between lack of

proficiency and rise in occurrence rates. The lack of a similar rise in in LOC-I occurrence for RPT

operations may be due to the stronger checking and training procedures within that section of the

industry, with a more gradual recovery of flight activity providing greater opportunity for flight crew

to regain proficiency over a more extended period.

While it may be possible to draw links between flight activity levels, occurrence rates, and

occurrence types to identify potential loss of proficiency, with the lack of direct flight crew testimony

in the NAOD dataset there is limited possibility to make causative statements for such a subjective

matter as personal proficiency. Within the ASRS dataset, greater access to narrative statements is

available with personnel citing concerns about lack of proficiency arising from flight hiatus as a result

of the Covid-19 pandemic across 2020 and 2021, with concerns about proficiency being 39 per cent

higher than pre-pandemic.

Beyond Covid

Future studies may take advantage of further data releases – namely more complete occurrence

datasets as ATSB and NASA upload further occurrences within the reporting periods covered in this

review, and further flight activity statistics being released in future – to form more complete

understandings of longer-term trends arising from variations in flight safety occurrence during and

after the Covid-19 pandemic. For greater understanding of risk profile changes that did not result in

flight safety occurrences, access to operator flight data monitoring datasets within the Australian

context may provide higher granularity and more predictive capability in application of long-term

trend data in the face of short-term disruptions to flight activity. Direct analysis of cohorts, such as

surveys or fleet management data may provide greater insight in future studies, although as time

progresses first-hand accounts of the Covid period may become more unreliable. A key limitation of

this investigation was a lack of direct access to monthly flight activity requiring estimation of

occurrence rates. In addition, the lack of published flight hours for 2022 leaves uncertainty to the

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exact levels of occurrence rates for that year requiring the assumption that post-Covid flight activity

is similar in makeup to pre-Covid.

Conclusion

The Covid-19 pandemic has had a measurable impact on flight safety occurrence rates in Australia

and in the United States. Between the United States and Australia, the greatest impact on

occurrence rates was seen in the US, with a mean monthly occurrence rate one and a half times

higher than pre-Covid, despite a greater fall in flight activity in Australia with more severe

government restrictions being implemented. In Australia, post-Covid occurrence rates have returned

to near pre-Covid levels with the exception of controlled flight into terrains occurrences which have

remained elevated. Despite the increased occurrence of CFIT, the greatest impact of Covid-19 on

occurrences in Australia was among runway incursion and excursion incident both overall and for

RPT operations, while GA operations saw the greatest increase in CFIT occurrences seeing runway

incidents falling through 2021 and 2022.

Victoria saw a greater increase on occurrence rates in both 2020 and 2021 when compared with the

states and territories that saw less severe government restrictions, while 2022 saw both groupings

saw occurrence rates return to a similar level as each other. Amongst the various operation types,

RPT saw the greatest initial increase in occurrence types as flight activity drastically fell during the

early period of the pandemic, but saw a consistent decline in occurrence rates throughout 2020 and

2021, with slight increases at the onset of lockdown restrictions, while general aviation saw a rate of

occurrences that remained elevated for a longer period throughout 2020 and 2021 with little

variation until the easing of restrictions in the latter parts of each year.

Throughout 2020 and 2021, occurrence rates indicate a potential likelihood for proficiency-related

increases in flight safety outcomes. These take the form of significant occurrence rate increases as

flight activity levels began to increase, increases in certain types of occurrences – such as runway

incursions and excursions – which often see procedural error and confusion as contributary factors,

and subsequent levelling out or fall in rates as flight activity recovery began to ease from its initial

fervour, with rates returning to near pre-Covid levels by the beginning of 2022. Within the ASRS

dataset, flight crew narratives saw proficiency concerns rise nearly forty per cent above pre-Covid

levels indicating that flight crew were self-identifying potential loss of proficiency as a potential risk

factor.

While direct measurement of flight hours and activity was not directly available for both the United

States and Australia, the author believes that use of estimated occurrence rates from a hybrid of

flight hours and airport movements provides sufficient understanding of the overall levels of activity

and consequent occurrence rates to examine trends in flight safety datasets such as the ASRS and

NAOD databases. Future studies may take advantage of future releases of flight activity statistics to

provide greater levels of detail and granularity in occurrence rates. With access to airline flight data

monitoring and crew reporting systems, future research involving direct pilot testimony within the

Australian context may provide for greater insight to the mental impact that the Covid-19 pandemic

had on flight crews and flight safety, while also identifying how crews best responded to return to

service strategies with the aim of ensuring flight safety in the face of future local and global flight

activity upsets similar to those seen throughout 2020 and 2021.

Datasets and derived worksheets available on request.

AVA80037  Impacts of the Covid-19 Pandemic  Rory Buchanan 
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Human Factors  and Pilot Proficiency 
36 
 
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