Managing wildlife hazards to aircraft

Collisions between aircraft and wildlife have been acknowledged as a hazard to aviation since the first aircraft flew over 100 years ago. But despite many years of research into combatting the problem, wildlife strikes continue to be a serious safety concern for aviation regulators, airlines and airports.

Occasional high-profile incidents, such as the crash of Flight 1549 into the Hudson River in 2009, bring the issues to the attention of passengers and the general public, but for the most part this is a risk that is not fully appreciated, even within the industry itself. It is not just the high-profile incidents that make the headlines that are of concern. Thousands of minor incidents, most causing no damage to aircraft, result in precautionary turn backs, engine checks, delays, cancellations and minor repairs that add up to at least $1.2 billion per year in operational costs to the world civil aircraft fleet.

With aviation predicted to grow for the foreseeable future, and increasingly successful efforts being put into wildlife conservation, it is likely that the risk posed to aircraft by wildlife will also increase, unless more effective measures are put in place to manage the problem. Available data supports this view, with reported wildlife strikes increasing in frequency year on year1. There is clearly a need to do more to prevent wildlife strikes, but opinion is divided about whether new technology is the answer, or just proper application of long established bird management methods. This article reviews the latest developments in wildlife strike prevention and assesses some of the reasons why we still struggle to get on top of such a long standing flight safety risk.

What do we know?

At its most basic, wildlife strike prevention revolves around ensuring that operational aircraft and hazardous wildlife are not in the same place at the same time. Around 90% of wildlife strikes happen on or close to airports, so the main thrust of strike prevention involves keeping hazardous wildlife off of airport property and out of the approach and departure corridors. If wildlife is on or near an airport it’s there for a reason, usually food or safety. The simplest, most effective, and permanent way to control the wildlife strike risk is to remove whatever it is that is attracting the creatures concerned.

For example, managing grassland to remove insects that birds can feed on, netting ponds and streams to exclude water-birds, improving fencing to exclude deer, blocking holes or crevices in buildings to stop birds nesting or roosting there, etc. It will never be possible to remove every attraction, however, and some form of deterrence will always be needed to disperse hazardous wildlife that continues to cause a risk. All of this is well understood and, if properly applied and supported by good advice and staff training on the choice of habitat management and wildlife dispersal techniques that are used, can make a major difference to the numbers of strikes that occur, the cost to the airlines involved, and the risk to the passengers and crew.

A recent initiative by Wizzair, a low cost carrier operating primarily in Eastern Europe, involved the airline insisting that the airports that it operated from were subject to an audit of their wildlife management practices from an outside agency. Wizzair commissioned the Birdstrike Avoidance Team from the Food and Environment Research Agency in the UK to assess the wildlife management practices in relation to International Birdstrike Committee Best Practice and make recommendations for improvements where needed.

Twenty six airports were selected for the programme and a total of 309 recommendations for improvements were made. Even without full take-up of the recommendations, the number of wildlife strikes at the airports fell by a total of 37.4% resulting in an operational saving of approximately €900,000 for the airline in the first year alone. None of the techniques recommended were particularly new or inno – vative, but this initiative demonstrates that the correct and diligent application of existing methodologies can have a major impact on both costs and safety risks arising from wildlife strikes.

So why do wildlife strikes continue to cause increasing risks and costs, if such a major difference can be made by just doing what we already know? The problems revolve around two basic issues – a lack of effective regulation and enforcement, and a disconnection between those who have to fund wildlife management and those who benefit from it. 

Who regulates the regulators?

The International Civil Aviation Organisation (ICAO) has set Standards and Recommended Practices (SARPS) for the management of wildlife hazards around aerodromes. Individual states then enact the SARPS via their own rules and regulations. Some states have detailed require – ments and supporting advice as to how wildlife hazards must be controlled, but others have little or nothing in terms of wildlife management requirements. It is also the responsibility of the different states to enforce the regulations that they set, and even those with well-thought-out regulation may not have the capability to effectively police the implementation of their own rules because their inspectors lack the skills to recognise effective wildlife management in the field.

Other safety provision, such as the type and number of fire appliances or the possession of necessary instrument landing systems, are precisely defined for a particular category of airport and thus relatively easy to audit. Wildlife management requirements are frequently very loosely defined in national regulation and even those airports with detailed wildlife management plans in their Safety Management Systems may not implement them effectively. Inspectors, who have a wide variety of safety systems to audit, cannot be expected to be able to assess whether a wildlife management programme is fit to manage the hazard at an airport, nor whether it is being effectively implemented. The result is that many airports are not managing their wildlife hazards effectively, or, in some cases, at all.

Who pays the bills?

The second problem in delivering effective wildlife management is one of cost-benefit. It is the airport’s responsibility to carry out wildlife management activities, but they do not benefit from these on a day-to-day basis. There is clearly a benefit in that it makes it less likely that a serious accident will occur at the airport concerned, but the vast majority of wildlife strikes are minor in nature and result in costs to the airline involved that fall below the excess on their insurance policies and thus have to be absorbed as a routine operating expense.

So as the airport has no ‘spend to save’ incentive, and if the safety inspections con – centrate more of the presence or absence of a plan for wildlife management rather than whether it is fit for purpose or being correctly applied, then the temptation is to save money by cutting back on staff time, equipment or other investment in wildlife management. Where a particular airline is the single major customer at an airport, it may be possible for them to put pressure on the airport operator to invest in wildlife control. Alternatively, an airline’s insurers may be prepared to invest in managing the risk at an airport, either by paying for advice and training or by funding investment in wildlife management to manage their exposure to the rarer, but more serious, wildlife strike events.

How can innovation help?

Given that regulation and inspection is not all it might be, and that there is little incentive for airports to invest in established wildlife management processes, are there new tech – nologies on the horizon that can provide simple and comprehensive solutions and that are also easy for regulators to evaluate?

The simple answer is no, because the wildlife problem varies so much between different airports in different environments, there is not one simple solution that airports can be required to implement. This is not to say that there are not new tools becoming available for wildlife managers on airports, but the challenge remains to understand enough about the problem to be able to select and implement the correct tools in the right way. The issue is, and will continue to be, identifying the things that attract wildlife, removing or reducing them as far as possible, and then detecting and dispersing any hazardous wildlife that remains.

The grass isn’t always greener

The vast majority of airfields are maintained as a combination of hard standings (tarmac or concrete runways, taxiways and aprons) and grassland. Aside from ensuring that hard standings are well drained to avoid providing pools of standing water for wildlife to drink or bathe in, there is little that can be done to make it less attractive to wildlife species that value open spaces as a safe place to rest.

The management of the airport’s grassland, however, is a different issue, with widely differing opinions about how the grass should be managed in terms of height, cutting frequency, harvesting a grass crop for animal feed, presence of ‘weed’ species etc. Much of the controversy revolves around a desire to have a ‘one size fits all’ method for grassland management. The complex mowing and spraying regimes that work well to keep birds away from the warm wet airfields of western Europe, where grass grows all year round, do not work on airfields in the deserts of the middle east where to grow grass at all requires large amounts of irrigation and the creation of what is effectively an oasis of green in an otherwise arid environment.

Whilst the environmental conditions, and hence the plant species and wildlife, present on airfields around the world may vary, the basic principle of identifying the attraction that brings the wildlife there and either removing it, or denying access to it, remains the same. Much of the attraction offered by airfield grassland arises from the smaller creatures that live within it; insects, worms, rodents etc. that act as food for larger hazardous wildlife. Work in New Zealand to develop grass strains that have fungi growing within them which produce chemicals that make the grass taste unpleasant or which, in high concentrations, could even be toxic to insects and rodents, has the potential to deal with a number of the features that attract hazardous wildlife at source. These ‘endophytic’ fungi occur naturally in many grass species, and strains have been selected that have produced higher levels of certain alkaloid chemicals that have been shown to reduce the insect populations in trial areas. The impact on rodents is less clear, and full scale trials on airfields have yet to be completed, but if this can be applied successfully it has the potential to greatly reduce the attractiveness of airfields to a wide variety of bird species.

An alternative to developing new varieties of grass for airports is to dispense with grass cover altogether. Some airports in drier climates have been looking into using different plant species that do not need watering but which suppress dust and debris from being blown onto runways by jet engines. If these do not attract large numbers of invertebrates and rodents they won’t attract hazardous wildlife.

Another option would be to dispense with vegetation as a cover for airfields entirely. The latest developments in artificial turf have been designed to be load bearing so that aircraft which leave the runway for any reason are not compromised, and they offer little or nothing in terms of food for insects. Large areas of artificial turf may still offer security for bird species that like open spaces, but it may be possible to include taller stiffer artificial grass stems to block the bird’s vision of the surrounding environment and remove their feeling of safety.

As with endophytic fungi in grass, large scale trials are needed, and the costs of installation would be considerable, but set against a continued need to manage grassland or other vegetation and the associated costs of wildlife dispersal and risks from the presence of wildlife that remains, these techniques can potentially offer a long-term solution in the right circumstance.

What is out there at the moment?

Given that there is no immediate prospect of implementing airfield ground cover that does not attract some sort of hazardous wildlife, knowing what wildlife is on the airfield is a prerequisite of being able to disperse it. Existing technologies, such as thermal cameras, acoustic detectors and radar systems are being developed specifically to detect birds and other wildlife on airfields, and in some cases to provide early warning of the approach of hazardous wildlife towards the operational airspace.

It is clearly beneficial to know what risks are present on an airfield, especially in the hours of darkness or in low visibility conditions when conventional observation from vehicles or from the tower is impossible, but this technology is not a substitute for effective habitat management and wildlife dispersal. If an airport has a mechanism for monitoring the hazards on its property it has a moral, and probably also a legal, duty to do something about it.

Systems already exist for closing runways or entire airports if environmental factors like low visibility, wind-shear, thunderstorms or runway friction fall below prescribed levels. How is an airport operator to respond if a detection system shows numbers of hazardous wildlife to be over a certain threshold, and what is that threshold? How often would you close a runway in response to the presence of hazardous wildlife? What would be the economic cost to the airport? What would it save airlines in terms of cost of damage and delays? How do Air Traffic Controllers interpret data from these detection systems? All of these questions need to be answered if we are to move to a situation where we control the aircraft to keep them out of the airspace occupied by wildlife. In the meantime, we must concentrate on keeping the wildlife out of the airspace occupied by aircraft.

Along with building the better mousetrap, the development of better techniques to deter wildlife from crops, buildings and other areas where they cause conflicts with man, has been the subject of much innovative thought, and a good deal of nonsense, since the construction of the first scarecrow. Some of the most recent developments in airfield wildlife deterrents involve both the old and the new.

Dogs have been used by hunters, shepherds and many others for thousands of years, but their use on airfields has only recently gained a measure of acceptance. Free-running dogs have traditionally been regarded as an unacceptable safety risk on airfields, but it has been shown that dogs that are specially trained to work either on airfields themselves or on land outside the airport fence, can be extremely effective in dispersing birds such as geese, gulls and other bird species that use airports to rest or feed. Dogs – regarded by many wildlife specialists as a natural predator – can also be trained to sniff-out nests of breeding birds or to help with control of mammals such as rabbits, and they have the advantage of being able to cover large areas quickly, often accessing areas that vehicles cannot reach.

Dogs are less effective for birds that spend a lot of time in flight or that rest on large lakes or reservoirs – in these cases, another technique that has raised safety concerns in the past can be deployed to good effect. Lasers have been shown to be very effective in dispersing gulls and waterfowl from lakes and can be used to harass bird species in the air. They work better in low light levels or at night and extreme care must obviously be taken to avoid dazzling pilots, but laser torches or fixed laser installations have been safely deployed effectively at a number of airports in the past few years.

So, we have new tools for making airports less attractive to wildlife, new tools for knowing where the wildlife is, and new tools for deterrence. None of these will necessarily work, however, unless the correct tool is chosen, properly deployed and its impact properly assessed. This needs to be driven by good regulation and proper enforcement by safety inspectors who know what an effective wildlife management programme looks like; on the ground as well as on paper. Until we have this in place, we will continue to suffer financial loss and occasional catastrophes as a result of wildlife strikes. We may not be able to eliminate the risk entirely, but we have the tools to do a much better job than we are at present. We just need to apply them properly.

Reference

1. http://wildlife.faa.gov

Biography

Dr John Allan is Head of the Wildlife Programme at the UK Govern ment’s Food and Environ – ment Research Agency. He has worked as a specialist in wildlife management on airports for the past 23 years and was Chairman of the International Birdstrike Committee (the main professional body for specialists in the field) from 2005-2012. He received the Mike Kuhring award for achievements in birdstrike prevention in 2003. His main research interests are the objective assessment of risk from birdstrikes to aircraft and development of audit and best practice standards for bird manage – ment on and around airfields.