Bird Strike Control

Bird Strike Control

Bird strike events surge with an increase in the number of annual flights. Mostly, the event occurs at low altitude or on the ground, but with benign effects. However, this does not rule out bird strikes as harboring safety consequences in flight operations. As such, it is the responsibility of flight operators and pilots to exercise utmost care and to obtain necessary knowledge regarding potential hazards. Flight crews, on the other hand, should utilize standard operating procedures, facts and data to minimize consequences in case of a bird strike. While bird strikes are increasingly becoming less hazardous to aviators, control measures should be exercised to protect wildlife and minor plane damages (Thorpe, 1997).

A bird strike refers to a collision of a man-made vehicle—especially an aircraft—and airborne animals such as bats and birds. It can also refer to bird deaths due to accidental collisions. The collisions can occur between the birds and structures such as power lines, wind turbine and control towers. During aviation industry’s infantry years, bird strikes posed a significant threat to flight safety. Fatal accidents were common (Burger, 1983). Today, technological advancement in turbine engine designs has lowered the number of major accidents remarkably. Up to 65% of bird strikes in modern times cause insignificant aircraft damage but birds involved hardly survive.

There are two ways that bird strikes occur—a bird can collide with the plane’s windscreen or it can be sucked by powerful wind gusts into the craft engines. In the United States alone, the collisions and the resulting damages approximate losses of up to $400 million. Besides, there has been a sharp global decline in the numbers of avian species—experts consider the collisions with man-made structures and airplanes as one of the major contributors.

Forensic Analysis

When a flock of birds strikes, disastrous consequences ensue. Multiple strikes on low flying aircrafts make it hard to recover flight traction leading to crash imminence. Whenever a bird strike occurs in the United States, victim bird carcasses (also referred to as snarge) are shipped to identification centers for forensic analysis. To minimize risks of zoonoses, trained personnel handle the needed samples carefully during analysis.

Bird Species

Large birds with big populations like gulls and geese are mostly involved in accidents with aircrafts. In Canada and United States, scientists have observed an increase in migration of geese population, hence raising concerns regarding flight safety (Alge, 1999).  Milvus and Gyps vultures wield greater potential of strikes with aircrafts in other parts of the planet.  Latest reports of bird strike in the US involved waterfowl, raptors, and pigeons. The strike incidences were mostly concentrated in fall and spring seasons when most birds are on a migratory path.

Approaches to Minimize cases of Bird Strikes

There are three main approaches for control of effects of bird strikes. Aircraft designers should consider plane designs that are more resistant to bird strikes. Secondly, relevant authorities should consider measures that move birds away from runways and flight paths. Lastly, aircrafts and airports can be moved away from bird habitats and migratory paths.

Aircraft Design

Latest designs of commercial jet engines involve features that ensure immediate shutdown upon an ingestion of no more than 1.8 kg bird. It is not necessarily imperative for engine to be functional after ingestion, but safety is a fundamental concern. The requirement is ‘stand-alone’ because the turbine engine ought to meet all test requirements—not the aircraft. Notably, bird flock multiple strikes on both aircraft engine mid-air can be more serious than earlier thought.  They result in an immediate shutdown of vital aircraft system prompting emergency landing actions.

Main requirements of modern large aircraft structures are tail's ability to survive an 8lb bird collision and craft windows' ability to withstand a 4lb bird strike without spalling. In the past, manufacture’s tests of bird strikes involve bird carcasses being fired into the tested unit. This is made possible by a powerful gas cannon and a sabot system that simulates a speed of a bird on course to collide with an airplane (McCarthy et al., 2004). However, modern advancement in computer technology makes it possible to employ computer simulation in conducting bird strike tests. This minimizes test costs though carcass firing is still applicable in final test phases (Georgiadis et al., 2008).

Modern jet engines have white spirals painted at the center. On the ground, a white spiral indicates a running engine to the crew but in the air, it destructs the birds hence discouraging them from flying in.

Management of Wildlife

It is true that there are multiples of methods applicable by wildlife in curbing bird strikes, but there is no single universal method for controlling all bird species at all instances. Airport wildlife management measures can be categorized into two groups—lethal and non-lethal measures (Brown et al, 2001). Application of multiple lethal and non-lethal methods has proved to be an effective strategy in managing airfield wildlife.

Non-Lethal Control Measures

Non-lethal airfield wildlife management measures include visual and auditory measures, use of chemical repellents and relocation of wildlife to avert harmful consequences. Habitat manipulation, tactile and exclusion measures are also applicable. 

Habitat Manipulation

Wildlife is present at airports because of food abundance. To minimize wildlife presence at airport environment, sources of animal food at the airport can be minimized or eliminated. Turfgrass, for instance, is in plenty in most airports, hence attracting many animals as a source of food.  While grass is planted to reduce soil erosion and absorb jet wash, its preference as a source of food for most birds makes it dangerous (Brough & Bridgman, 1980). As such, airport authorities should consider ways of minimizing its attractiveness as bird food.

Birds Exclusion

Total exclusion of birds in an airport environment is an impossible feat. However, large birds and other land animals like rodents can be excluded. Barbed wire fences should be installed as perimeter fences to keep off animals.  Besides, a perimeter fence keeps off unauthorized people.Hangars should have doors that are closable when the structure is not in use to keep off birds from building nests.

Visual and Auditory Repellents

            Visual and auditory repellents can be applied as harassment techniques at the airport. Visual repellents include use of dogs, birds of prey and lasers to scare off wildlife at the airport (Lustick, 1972). Dogs are effective visual deterrents that harass birds effectively. As such, most airports with annoying bird population are considering the use of dogs and other visual repellents.

On the other hand, auditory repellents such as propane exploders, bioacoustics, shotguns and flare pistol sounds can be deployed at airports. Noises that propane exploders produce are so powerful that most bird species will flee with immediate effect.

Relocation

Most biologists prefer relocation of birds such as raptors rather than application of lethal measures. However, relocation of birds from their natural habitat due to human activities involves lengthy legal issues. The law requires relocation experts to obtain necessary permits and should take adequate measures to minimize bird casualties during the process. Relocation is considered as one of last resort measures.

Lethal Control Measures

In airports, lethal wildlife control involves population control and taking measures that reinforce non-lethal means.

Reinforcement of Non-lethal control methods

Wildlife harbors potential to lash out after non-lethal controls are enforced. Propane exploders, for example, elicit wildlife's danger response. Over time, the targeted wildlife becomes habituated to non-lethal measures. Consequently, wildlife culling is enough to restore danger response.

Population Control

There are times that wildlife population explodes threatening to spiral out of control. In an airport environment, a population of bird species can rise because of abundance food and shelter. The explosion multiplies dangers as most birds will be on air when planes are landing or taking off. As such, government can authorize elimination of some birds to keep population in check (Cook et al., 2008). This usually happens when the birds cause accidents or when there are proofs of multiplication of dangers at the airport. Usually, sharpshooters are assigned the task.

Flight Path

            Pilots should be trained on how to avoid birds while in the air. They should be knowledgeable on halting takeoffs and landing protocols when birds are in plenty. Besides, pilots should avoid bird migratory routes through alteration of flight paths. Aircrafts that are taking off from the ground are more prone to bird strikes than those in high altitudes are. Thus, pilots should consider a steep ascent to more than 3000 feet to minimize chances of a bird strike. 

 Advancement in technology and creation of awareness is making bird strikes less of a concern in aviation industry. However, more needs to be done to ensure zero rates of accidents. Because annual human fatalities as a result of bird strikes have dropped significantly, the focus should shift to finding ways to protect wildlife from human encroachment to their natural habitat.

References

Alge, T. L. (1999). Airport Bird Threat in North America from Large Flocking Birds (geese)(as Viewed by an Engine Manufacturer).

Brough, T., & Bridgman, C. J. (1980). An evaluation of long grass as a bird deterrent on British airfields. Journal of Applied Ecology, 243-253.

Brown, K. M., Erwin, R. M., Richmond, M. E., Buckley, P. A., Tanacredi, J. T., & Avrin, D. (2001). Managing birds and controlling aircraft in the Kennedy Airport–Jamaica Bay Wildlife Refuge Complex: The need for hard data and soft opinions. Environmental Management, 28(2), 207-224.

Burger, J. (1983). Jet aircraft noise and bird strikes: why more birds are being hit. Environmental Pollution Series A, Ecological and Biological, 30(2), 143-152.

Cook, A., Rushton, S., Allan, J., & Baxter, A. (2008). An evaluation of techniques to control problem bird species on landfill sites. Environmental management, 41(6), 834-843.

Georgiadis, S., Gunnion, A. J., Thomson, R. S., & Cartwright, B. K. (2008). Bird-strike simulation for certification of the Boeing 787 composite moveable trailing edge. Composite Structures, 86(1), 258-268.

Lustick, S. I. (1972). Physical Techniques for Controlling Birds to Reduce Aircraft Strike Hazards:(Effect of Laser Light on Bird Behavior and Physiology). OHIO STATE UNIV COLUMBUS.

McCarthy, M. A., Xiao, J. R., McCarthy, C. T., Kamoulakos, A., Ramos, J., Gallard, J. P., & Melito, V. (2004). Modelling of bird strike on an aircraft wing leading edge made from fibre metal laminates–Part 2: modelling of impact with SPH bird model. Applied Composite Materials, 11(5), 317-340.

Thorpe, J. (1997, August). The implications of recent serious bird strike accidents and multiple engine ingestions. In International Workshop on New Technologies for Bird Strike Prevention, Boston, US.