Birdstrikes are on the rise and business aircraft are particularly susceptible due to their high percentage of time at lower altitudes and use of smaller airports.
In recent years, the so-called Miracle on the Hudson is the most high-profile case of a bird strike downing an aircraft. Thankfully, that incident ended with all 154 passengers and crew walking away unscathed, but birdstrikes account for dozens of deaths and more than an estimated billion dollars of aircraft damage each year.
Bird strikes are a considerable problem for the business aviation community if only because bizjets utilise an extensive network of airports that scheduled airlines never use. In the US, more than 5,000 airports are visited by business aircraft while commercial aircraft only use 550. The European Business Aviation Association (EBAA) reported in their document “Getting to the Point” that the network of airport pairs linked by business aviation has 100,000 links – three times as many as the scheduled flight network. This Eurocontrol study found that business aviation has its share of long haul but only 9% of business flights are over 2,000km and nearly half of business flights under 500km.
Since most bird strikes occur below 500 feet Above Ground Level and pilots rarely encounter birds above 3,000 feet it follows that business aircraft spend a larger proportion of their flight time in these lower AGL zones, therefore facing a greater risk of strikes. According to EASA’s safety analysis on bird strikes, 84% of bird/wildlife strikes that lead to accidents occur during the take-off and landing phase of flight.
Recent statistics suggest that bird and wildlife strikes to aircraft in the US civil and military administration results in US$650 million in damage and down-time costs and more than 200 passenger deaths worldwide. About 5,000 bird strikes were reported by the US Air Force in 2010 and over 9,000 bird and other wildlife strikes were reported for US civil aircraft in the same year. More than 950 civil aircraft collisions with deer and 320 collisions with Coyotes were reported in the USA between 1990 and 2009. In this period 415 different species of birds and 35 species of terrestrial mammals were involved in strikes with civil aircraft in the US. In a 14-year period, US airlines reported over 30 incidents in which pilots had to dump fuel to enable emergency landings. An average of 11,600 gallons of jet fuel was dumped in each of these emergencies.
According to Phil Mountain, Director of Operations at Birdstrike Management Ltd, global bird strike incident costs are not easy to record.
“It is extremely difficult to say what the total costs are but EASA estimates that one billion Euros are the losses incurred annually. They also estimate that losses of 15,000 Euros per non-damaging strike and 150,000 Euros per damaging strike as a realistic figure.”
Phil’s company has been very active in reducing bird strike risks and costs for many airlines and halved the costs and risks for major Hungarian airline Wizz.
“The Wizz Air project is an ongoing bird strike operating cost reduction programme. Wizz identified airports where they were experiencing a high level of bird strike incidents. At the time BML staff worked for the UK Government within the FERA Birdstrike avoidance Team and Wizz contacted me to provide a Standards Check Audit of several European Airports to provide an independent review of the efficacy of their Wildlife Hazard Management Plan.
“The reports are positive documents designed specifically to help airports improve the effectiveness of their WHMP to International best practice as set out initially in the IBSC (International Birdstrike Committee) standards (and latterly to the new EASA legislation). The project has been a demonstrable success and has helped reduce the WIZZ damaging bird strike rate by 50%. We have also provided training for 50 delegates from 20 European airports.”
Evidence gathered by The International Bird Strike Committee and presented as an “Illustrated Working Paper” 2003, showed that executive jets comprised 37% of fatal accidents in the section of Transport Aircraft and Executive Jets which registered ten fatal accidents, 164 deaths and 30 write-offs and aircraft in the 5,700kg and less category registered 27 fatal accidents, 58 deaths and 42 write-offs. All 27 of the fatal accidents involved general aviation aeroplanes which the committee noted are not required to be designed to withstand bird strikes with 52% of accidents caused by holed windscreens, which amazingly can be caused by a bird as small as a swift.
Typically most bird strike damage to jets is caused by bird ingestion which can disable engines completely or produce sufficient damage that reduced thrust often causes return to the airport of departure or a forced landing. A typical example of this kind of damage occurred when a Falcon 20 took off from Paris Le Bourget and encountered a flock of Lapwings. Several were ingested in engine 1, the aircraft was climbing but the pilot reported he was returning due to an engine fire. The fire was seen by witnesses who saw the rear of the aircraft engulfed in flames. The aircraft was destroyed by impact and fire. 15 dead birds were found on the runway at take-off point. The engine rear cowling, exit guide vanes and a number of fan blades were found further along the runway. The fan had separated and shrapnel had penetrated the rear fuselage puncturing the engine feeder tank causing the fire. It was stated in litigation proceedings that the person responsible for bird control was off sick at the time of the incident.
One of the most famous incidents occurred in 2009 when the US Airways flight from LaGuardia Airport made a forced landing into the Hudson River after losing power in both turbines having struck a flock of geese at 3,200ft shortly after take-off. All 150 passengers and 5 crew members were saved. The first officer was handling pilot. As they reached an altitude of 3,200 feet they encountered a formation of Canada Geese. Impacts were felt, both engines began to lose power and there was a burning smell. The pilot, Chesley B “Sully” Sullenberger, took over the controls and after contact with ATC decided to land the plane on the Hudson River.
Several factors have contributed to the current higher risk factor posed by bird strikes. In North America alone the non-migratory Canada Goose population increased from one million birds in 1990 to more than 3.9 million in 2009 and the North American population of Greater Snow Geese increased from about 50,000 birds in 1966 to more than one million birds in 2009. This presents a huge problem for aircraft if they run into these birds which average 12 pounds in weight and if one hits a plane travelling at 150mph it generates the kinetic energy of a 1,000 pound weight dropped from a height of 10 feet. There were fewer than 400 pairs of Bald Eagles nesting in North America in 1970 compared with 13,000 pairs in 2010. It is no wonder that the FAA and the CAA feel the need for robust bird strike mitigation policies aware that the bird strike menace may be reaching a critical level.
The CAA note that traditionally a dual approach has been taken to reduce the risk of catastrophic bird strikes which has involved employing airport bird control measures such as Birdstrike Avoidance Radars which are made by DeTect Merlin Systems. There are over 140 Merlin Systems currently operating at sites worldwide in aviation safety roles. Their technology provides real-time display of bird activity with high update rates, precise, tactical automated bird-aircraft strike risk alerts to controllers and pilots and detects birds from ground level to above aircraft operational altitudes. This system offers reliable bird detection in up to moderate fog, rain and snow conditions.
Birdstrike Avoidance Radars made by DeTect Merlin Systems can help reduce birdstrikes
Clearly for larger airports used by scheduled airliners and military airports the cost of this technology represents a small part of their budgets but for more remote, less-used airports buying or leasing this equipment may not make sound economic investment sense with each Merlin System costing between US$500k to US$750k per runway. However with bird strikes increasingly becoming a litigation issue where airports are often on the losing side it may be money shrewdly spent, to say nothing of eliminating bird strikes that can result in passenger and crew fatalities.
In the search for methods used to mitigate bird strike risks many natural predator options have been employed. At Fort Myers, Florida a border collie has successfully policed the perimeters of the airport and has achieved a 17% drop in bird strikes scaring off Egrets, herons and moorhens who have grown used to pyrotechnics but have not adapted to the presence of the dog. Pigs have been used to trample and eat gulls eggs forcing them to find alternative locations. Removing vegetation deters settlement.
While great strides have been made in mitigating bird strike and wildlife risk there are situations, thankfully rare, where strikes have been recorded at altitudes above 30,000ft. A Bombardier Challenger 300 hit five soaring turkey vultures at 1800ft on climb from Florida Airport in 2013. The pilot declared an emergency and landed safely at an alternative airport. Repair costs for engine and tail were over US$800,000. The aircraft was out of service for 22 days.
According to a government industry bird strike committee there were 2,200 bird strikes at altitudes of more than 5,000ft between 1990 and 2008 with the highest altitude incident reported as a collision between an aircraft and a Griffon Vulture at 37,000ft off the coast of Africa. Thankfully not many birds are interested in joining the seven-mile high collision club.