Managing Birds

On January 15, 2009, the US Airways Flight 1549 took off from LaGuardia airport, New York, and landed in the Hudson River after sudden loss of power on both engines. It was a case of the Airbus 320-214 flying into a flock of geese at an altitude of 3,200 feet shortly after take-off. After a near copybook touchdown over water, all 150 passengers were rescued safely. For display of exceptional leadership in crisis, professionalism of a high order, Captain Sullenberger became an aviator’s hero. In aviation, when a bird or a bat impacts an aircraft in flight or is ingested by the engine, the episode is classified as a ‘Bird Strike’. Such an episode is a serious aviation hazard. The most serious situation is when the bird hits the wind screen or is sucked into the engine. Obviously, the birds do not like the idea of humans getting into their exclusive domain because a strike invariably means sure death for them. As per the International Civil Aviation Organisation (ICAO), 90 per cent of birdstrikes happen during take-off and landing phase and only six to seven per cent hits result in significant damage. The wildlife hazard manual of the Federal Aviation Administration estimates 61 per cent strikes occur below 100 feet and less than eight per cent strikes above 3,000 feet. The highest recorded birdstrike involving a vulture occurred at 37,100 feet.

Dynamics of BirdStrike

A bird impact occurs normally on the front sections of the aircraft wing or nose areas. Sometimes birds get sucked into the engines resulting in damage to the engine and loss of power. Very finely balanced compressor blades of a jet engine rotate at very high speeds and as such are very highly susceptible to damage. A bird ingestion at high power settings can have catastrophic consequences. A five-kilogram bird hitting at 275 kmph dissipates energy equivalent to a 100-kg weight dropped from 15 metres. Military and civil operators, therefore, study the pattern of bird activity in the vicinity of airports. Airports close to migration routes have statistically higher birdstrikes. Remains of birds are subjected to forensic analysis to ascertain the species type. While gulls and geese hits are more frequent in North America, vulture hits affect aviation in India the most. Small birds crossing the runway at night also account for bird hits.

Aircraft designers have been engaged for years in an effort to improve resistance to birdstrike. Ideally, prevention of birdstrike would be the preferred option. Jet engines are designed to withstand a four-pound bird strike up to 500 kmph. Other metal parts must withstand eight-pound bird collision. These parameters are validated on test-bed before certification.

Airfield Environment

Every airfield has its terrain and environmental peculiarities and hence action plans to combat bird hazard are devised based on local conditions. Bird hazard management teams at airfields work to ascertain and then prevent bird activity in and around airfields, promote bird-unfriendly vegetation and address food-waste and carcass disposal management. Use of bird scaring devices such as scarecrows, acoustic devices, light reflectors, pyrotechnics, remotelycontrolled small planes, laser guns, trained falcons to scare birds and even electrified mats to deny worms to birds is now common around the world.

The local administration has a major role in keeping the area in the vicinity of airports sterile. Fishing ponds, butcheries, waste and carcass dumping grounds attract birds and need regulation. Pilots and controllers have to take the final call. Take-off should not be authorised in case of bird activity on take-off path. Departure and arrival procedures need a review in case water bodies, bird sanctuaries, wildlife zones are located along the climb and descent paths. Data from Avian radars compiled over time reveal bird activity patterns. Such radars are being introduced at busy airports. Royal Netherland Air Force cut birdstrikes by half by installing such radars at their airfields. Airborne birdsurveys are also routinely ordered by aviation authorities for zones where the aircraft are likely to be flying at low height.

Cost of BirdStrikes

UK’s Central Science Laboratory estimates that birdstrikes cost airlines around the world about $1.2 billion annually. This includes repair and downtime costs. The fact is that about 80 per cent of birdstrikes are never formally reported. The first birdstrike was reported by Orville Wright in 1905 while flying in the circuit area. A French pilot, flying in an open cockpit, during an air race in 1911, fired her pistol to scare away birds in the air. The first birdstrike fatality was reported in 1912 when a bird got jammed in the flight control cables resulting in the aircraft going out of control.

The greatest loss to life because of a birdstrike was in 1960 when an Eastern Air Lines Lockheed L-188 Electra flew through a flock of birds after take-off and lost power on all four engines. The aircraft crashed into Boston harbour killing 62 of the 72 onboard. In July 1962, the co-pilot of a Pakistani DC 3 was killed after a vulture penetrated the windshield during cruise. In 1992, a bird-strike caused the wing fuel tank and the aileron of a Cessna 401 to separate and sent the aircraft spinning out of control. In 1995, a USAF Boeing E-3 Sentry AWACs aircraft lost power on both its port engines following bird ingestion immediately after take-off. The aircraft crashed killing all onboard. Space shuttle Discovery had a birdstrike soon after lift-off on July 26, 2005. Because of very low speed, there was no damage. In January 2009, a Sikorsky S-76 helicopter experienced a birdstrike just above the wind screen. The impact activated the engine fire suppression system which in turn automatically shut down the engines and the helicopter crashed killing most onboard. In 2006 alone, over 5,000 bird-strikes were reported by the US Air Force.

Flying insects were a big nuisance during the days when pilots flew in open cockpits. For protection against insects, pilots had to wear tight fitting goggles. The US, Australia and the desert areas along the Indo-Pak border are infested with swarms of locust. I had been a member of a fighter formation that flew though a locust swarm in a low-level mission over the Thar Desert. Two aircraft suffered serious damage and most pilots faced difficulty in landing due to blood on the wind screens.

Corrective Action

Are birdstrikes reducing? The answer is no. Since 1970, strict environmental laws have been giving protection to birds. The population of some species is increasing considerably. Canadian geese increased from one million in 1990 to 3.5 million in 2006. However, most countries have enacted laws allowing the shooting of birds within the airfield zone.

The United States Department of Defense has created an online Avian Hazard Advisory System (AHAS) using network of radars to predict bird movements. It is available for civil use also. The level of risk is calculated based on the bird mass per square kilometre. Higher the figure, greater the risk. Severe risk zones are best avoided. Bird avoidance model (BAM) looks at bird breeding and migration database and the same is superimposed on birdhit database for analysis. Also, map of the landfill sites and waste incinerators and processing stations is overlaid. Similar initiatives are being looked at in India also.

With the rapid growth of aviation, it is becoming increasingly important to address the issue of birdstrikes.