Keeping birds in hand

Posted: 13 December 2010 | Nick Yearwood, Chairman of the UK Birdstrike Committee and UK Civil Aviation Authority (CAA) Safety Regulation Group Representative | No comments yet

Modern aircraft engines are designed and built to be resistant to multiple birdstrikes from birds of up to 4.5lb (2kg) in weight. The UK CAA has played a leading role in developing enhanced engine certification requirements and United States National Transportation Safety Board (NTSB)…

Modern aircraft engines are designed and built to be resistant to multiple birdstrikes from birds of up to 4.5lb (2kg) in weight. The UK CAA has played a leading role in developing enhanced engine certification requirements and United States National Transportation Safety Board (NTSB) and UK Air Accident Investigation Branch (AAIB) recommendations have served further to emphasise the need for such activity. This work has been conducted in co-operation with other safety regulators (the US FAA, Transport Canada and other agencies such as the European Aviation Safety Agency (EASA)) and the aero engine industry.

However, these aero engine requirements are only the last line of defence; it is far better to reduce the chances of birdstrikes happening in the first place. Bird control measures practised by airports are, in the main, an effective tool in the airport’s armoury. Accordingly, UK licensed airports have developed, together with the CAA, a series of programmes aimed at reducing the risk posed by birds, especially within the airfield boundary.

The birdstrike risk posed by large flocking birds, such as Canada Geese, is known to be on the increase in both North America and North Western Europe, largely as a result of an unchecked increase in bird populations, changing migration patterns (that may be attributed to climate change), wetland restoration, conservation programmes and changes in farming practices. Consequently, birdstrikes to aircraft by large flocking birds continue to be an area of safety concern to the UK CAA and national aviation safety agencies around the world.

An awareness of the birdstrike risk, involving ‘off-airport’ factors, has been greatly increased in the wake of the accident to US Airways in New York; where the risk posed by resident Canada Geese and other flocking birds in the vicinity of a number of New York airports had been known of for some time but the risks had not necessarily been addressed or mitigated to any effect.

Mitigation of the birdstrike risk, regardless of bird species, requires a combined and concerted effort by many stakeholders: such as airport operators, landowners, local and municipal government agencies, conservationists and planners. It may be that, in order to address this increasing risk factor, planning and wildlife management controls need to be both implemented and enforced in order to minimise bird habitat attractants and to ‘manage’ bird populations in the vicinity1 of airports. The responsibility for this sits largely outside the remit of aviation stakeholders, so it is important for both airport and airline operators and their representative associations to make their case with the local agencies in order to influence decision-making to focus on and preserve air safety.

Bird Hazard Management Plans

UK airport operators, as part of their CAA certification requirements, must have a Wildlife Hazard Management Plan that, in addition to outlining its policy on managing the risk posed by birds on-airfield, should include a hazard identification and risk assessment process, as well as an assessment of the bird attractant features and bird population in the vicinity. The assessment requires that the airport gathers intelligence off-airport and has procedures that describe the establishment of ‘bird safeguarding’ processes in dealing with local planning authorities. Importantly, airport operators should establish effective communication strategies with local landowners, in order to try to affect and influence farming practices that may lead to a reduction or eradication of the birdstrike risk. But, the CAA believes more can and should be done by all stakeholders to address the increasing risk posed by off-airport land management and developments.

Where ‘off-airport’ strategies are difficult to achieve to any great effect, then it is incumbent on airport operators to demonstrate to regulators and stakeholders alike, a more robust and proactive strategy towards their bird hazard management and control measures employed within the airport boundary.

This may be achieved by implementation of policies that require dedicated bird control staff operating at all times during aircraft movements; use of dedicated specialist bird control equipment and, ultimately, policies aimed at proactively managing problematic or high risk bird populations within the boundaries of permissions imposed by the relevant wildlife conservation agencies2.

Mandatory reporting of all birdstrikes in the UK

In the past 10 years, the CAA has overseen several initiatives aimed at improving the understanding and raising awareness of birdstrike risks. Accordingly, in December 2003, the CAA implemented the mandatory reporting of all birdstrike occurrences, regardless of whether or not damage was caused to the aircraft. This initiative was primarily aimed at improving the data set in order to gather more and better information on birdstrikes, so that new strategies could be developed and risk assessments could be improved on the basis of more reliable data. In the period since mandatory reporting was introduced, the number of birdstrike reports received by the UK CAA has more than doubled; indicating that there had previously been a large degree of under-reporting when voluntary birdstrike reporting was the norm.

However, most birdstrikes result in no damage to the aircraft and CAA figures between 2003 and the end of 2009 indicate that less 10% of strikes reported caused any damage to aircraft or resulted in any aircraft systems failure, whilst the number of strikes by large flocking birds for the same period shows a decrease.

The main beneficiaries of the improved data set, since the implementation of mandatory birdstrike reporting, are those agencies and stakeholders responsible for shaping airport bird hazard risk assessment and management strategies (such as the Food Environment and Research Agency’s Bird Management Unit), and crucial to this task is an accurate identification of birds involved in birdstrike occurrences and intelligence gathered off-airport.


The CAA’s view, and one which is largely accepted by aviation stakeholders, is that the volume of birdstrikes reported at a particular airport alone does not imply greater hazard. Caution should be exercised when drawing conclusions from raw data and in formulating airport birdstrike ‘league tables’. Such reports and tables can not only be misleading, but also potentially damaging to the reputation of the airport managing the risk, and become a deterrent to reporters. Raw statistics give no indication as to the preventative efforts made in managing the wildlife risk or the limitations posed by habitat, environment, or the prevailing wildlife laws in the locality. Similarly, the CAA believes the rate of birdstrikes per 10,000 Air Transport Movements also to be a potentially misleading metric when used to assess an airport’s birdstrike risk.

Unidentified Flying Objects

In a recent press release, the CAA indicated that some 40% of all reported birdstrikes contain no bird species information. The lack of reliable and accurate bird species information on strike reports may potentially adversely impact the ability of stakeholders to accurately assess and mitigate the birdstrike risk, as well as potentially masking underlying and problematic changes to bird populations and consequential birdstrike trends.

So in May 2010, the CAA launched a birdstrike identification awareness campaign aimed at all stakeholders who report birdstrikes, encouraging them to make every effort to identify the species of bird involved in a strike.

All UK airports, as part of their certification requirements, are already obliged to undertake a birdstrike hazard assessment, in accordance with CAP 772 (Birdstrike Risk Management for Aerodromes) and they are also encouraged to record locally all wildlife strikes, and to log dispersal activities by the bird control team out on the airfield.

Airport operators should also undertake, on an annual basis, detailed reviews of their bird hazard risk assessment, drawing upon the information gathered not just from strike reports but also records from bird patrols with bird sighting details, and local intelligence gathering details gained off-airport. Any subsequent changes to the hazard should result in changes to the management plan being clearly documented. The CAA believes the key elements to improvements in this domain are education, awareness, competency based training and continuous development and assessment of the airport personnel carrying out bird control duties.

Birdstrike Committee

In accordance with ICAO recommendations, the UK CAA hosts an annual national Birdstrike Committee (BSC). The purpose of the BSC is to engage aviation stakeholders, government organisations and other agencies, to serve as a focal point dealing with birdstrike related issues. The committee also provides for an information exchange, sharing information and best practice and also in using the committee as a stakeholder consultative group for the regulator when considering new strategies.

At the 2010 UK Birdstrike Committee, following the FAA’s decision (in the wake of the US Airways Hudson River accident) to open up birdstrike data into the public domain, the CAA asked UK stakeholder representatives whether such a move would be desirable in the UK; as a consequence, cognisant of the dangers of misinterpretation, a unanimous decision was taken not to provide aerodrome-specific data in the public domain.

The UK CAA currently shares birdstrike data with stakeholders on an individual basis and is keen to provide more data upon request for bona-fide risk assessment and statistical analysis purposes. Additionally, the CAA provides birdstrike data to the EASA and ICAO, as well as publishing disidentified data on the CAA website.

Airline operators

Whilst the focus on managing the birdstrike risk lies predominantly within the domain of the airport operator – largely due to the fact that circa 80% of all birdstrikes occur at heights when aircraft are in take-off or short final approach modes, and therefore within the airport boundary – it is encouraging to note a growing interest and engagement from airline operators and pilot representative associations. This has resulted in the CAA assisting with risk assessment methodologies and advising airline flight safety officials on aspects of wildlife controls at airports, and it is now common practice in the UK to see carriers conducting independent quality audits of bird hazard management at airports they fly to and from. The CAA is keen to encourage and support these initiatives and believes such efforts must continue and findings shared with stakeholders, but again, these strategies, may not solve the issue of bird hazards ‘in the vicinity’.

Grass and habitat

A sometimes overlooked but integral aspect of an airport’s bird hazard management programme is the quality and effectiveness of the airfield grass and habitat. Civil Aviation Publication (CAP) 772 describes what is known as a ‘Long Grass Policy’ (LGP) the primary purpose of which is to act as a bird deterrent. LGP practices have been in use in the UK at both civil and military airfields since the early 1970s. Trials and studies at airports have since proved a direct correlation between an effective LGP and a reduction in birdstrikes by certain species, concluding that good quality airfield grass, free from certain insects, weed and moss infestation, grown to the desired optimum height, will act as an effective first line of defence in keeping birds away from airfields. The CAA encourages and supports more work and research into this area.

More information

The CAA sets out its guidance on birdstrike matters in CAP 772 (Birdstrike Risk Management for Aerodromes) and, together with the Airport Operators Association and General Aviation Awareness Council, has published a set of Safeguarding Advice Notes dealing with the birdstrike risk and what stakeholders can do to influence and manage birdstrike related issues when dealing with factors beyond the airport’s boundary fence.

The CAA remains committed to helping improve the levels of safety in relation to birdstrike risks at UK airports and will continue to play a pivotal role in this regard.


1. In the UK, ‘in the vicinity’ is deemed to be within 13km from an airport.

2. In England, Natural England provides a General Licence for airport managers, to take or kill certain wild birds in order to preserve air safety 06_tcm6-7670.pdf

About the Author

Nick Yearwood

Nick Yearwood Chairs the UK Birdstrike Committee, and is the UK CAA representative on the International Birdstrike Committee; he has also spoken on Birdstrike Risk Management issues at the 2009 EASA-FAA Safety Conference in Athens, and at the 2008 US-Canada Birdstrike Committee in Sanford, Orlando. Nick has recently been invited to join the Advisory Board on a European Space Agency funded project, in providing a regulatory perspective on the feasibility and operational application on whether there is a role for integrated space and terrestrial services in detecting or predicting bird presences to assist with airport birdstrike risk reduction for civil aviation. Nick is currently assisting ICAO in project managing a stakeholder review of Part 3 (Bird Control and Reduction) of the Airport Services Manuals (ICAO Doc 9137).

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