AoC number
161
Primary domain
ENV
Secondary domain
OP
Description
Bird populations worldwide are increasing dramatically. For instance, the population of barnacle geese, a species native to the Arctic Circle, rose to a peak of 1.2 million individuals in 2015. While a triumph for conservation efforts, these increases in bird population, coupled with rising air traffic, have renewed the risk of bird strikes on aircraft. Such strikes usually disable the plane’s engines, as in 2009’s ditching of US Airways Flight 1549, but can damage all parts of the aircraft. Most are caused by larger waterfowl, including geese and ducks, who are responsible for 20% of such collisions worldwide. The EASA found an upward trend of approximately 3% per annum in regards to bird-strike aviation accidents.
Most bird strikes occur at lower altitudes, below 152 m. However, migrant geese pass above 152 m, so during migration season, the risk of lethal strikes increases. Understanding the flight patterns of migratory birds is key to ensuring successful flight operations and preventing strikes, as airlines can plan their flights around predicted migrations. At the ground level, mammals such as deer and coyotes can also pose a threat to airplane security, and must be accounted for when appropriate.
The rate of bird strikes is increasing due to increasing populations of various species of large flocking birds (particularly in regions of high-density air traffic), as well as increasing numbers of wetlands restoration projects near major airports and Metroplex regions, such as the San Francisco Bay Area. Attempted mitigations include restricting access to the geese’s habitat and food sources (i.e. producing taller swards of grass and cultivating species with less nutritional value), pyrotechnics and other audio-visual deterrents, and as a last resort, lethal control. Birds can habituate to audio-visual deterrents that do not harm them otherwise, negating their usefulness. To prevent this, companies such as Clear Flight Solutions and Falcon Environmental Solutions have utilized predators, either artificial (Clear Flight’s “Robirds”) or real (live falcons) to deter waterfowl from aviation sites.
Potential hazard
Approach and departure paths with greater exposure to over-water flight conditions and greater likelihood of bird strikes
The recovery ability for any kind of disturbance at lower altitudes is reduced significantly^l
Egregious hazards Include:
A/C Controllability
A/C control can be compromised or that there were control issues present
Fire
A fire may occur as a result of the strike
Multiple Systems Damaged
More than one system may be compromised as a result of the strike, e.g. an event where LE slats, propulsion, and fuel system were all damaged and adversely impacted the flight.
High Speed Rejected Take-Off (RTO)
RTOs are a high risk event. Subject to speed, runway conditions, runway length, etc.
Loss of/Unreliable Cockpit Data
Data systems that supply the cockpit are either lost or no longer reliable. This includes, but is not limited to, air data, communications, nav data.
Cockpit Intrusion (Risk of Pilot Incapacitation)
Strike resulted in the bird entering the cockpit.
Last update
2017-08-28
Corroborating sources and comments
July 20, 2013: Bay Area sea gull population explodes, bringing flocks of problems, http://www.mercurynews.com/science/ci_23680401/bay-area-sea-gull-population-explodes-bringing-flocks
UK CAA studies on large flocking birds.
http://www.easa.eu.int/rulemaking/docs/research/Final%20report%20Bird%20Strike%20Study.pdf
Wildlife Significant Strike Categories, presented top the U.S. CAST, February 7, 2013
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5316332/ (Approximately 20% of all bird strike aviation accidents are caused by ducks and geese, and goose populations are climbing due to conservation efforts. The annual cost has been estimated as $1.2 billion for airline services, and the impacts can also lead to lost human lives. Migrant geese pass infrequently, but at higher altitudes [above 152 m], where the risk of lethal strikes are higher. The population of migratory barnacle geese increased to 1.2 million by 2015, and although they may not pose a major danger to air traffic in their region [Russian Arctic], other species are growing at similar rates. Mitigations include reducing access to the geese’s habitat and food sources, acoustic deterrents, and introducing predators. Dated 2017.)
http://www.boeing.com/commercial/aeromagazine/articles/2011_q3/4/ (Boeing’s take. The risk of wildlife collision is real and increasing, due to increased air traffic and increased bird populations in equal measure. Beyond waterfowl [31% of U.S. collisions], gulls [25%] and raptors [18%] were the most likely species to cause collisions in U.S. airspace, mostly at ground level. This document has greater emphasis on bird avoidance than the previous source, and features more statistics on rising bird populations.)
http://globalcocktails.com/airport-uses-falcons-control-bird-populations/ (One airport’s strategy to mitigate bird accidents is through falconry. A company called Falcon Environmental Services hires out falcons to airports for use in protecting aircraft; unlike with audio-visual noise and hazing, birds tend not to habituate to falcons. Company website here: http://www.falconenvironmental.com/)
https://www.usatoday.com/story/travel/flights/2013/04/01/airports-plane-bird-strikes/2043411/ (In 2012, 11,590 bird-aircraft collisions were reported. Traps, predators, and hunting programs have all been used to combat them, along with traditional methods. Note in particular that mammals, such as deer and coyotes, could also pose a threat, especially during landing procedures.)
https://clearflightsolutions.com/ (Possible mitigation. Clear Flight Solutions has adopted “robirds” and custom drones to fend off bird populations in the air. Robirds, in particular, create an unpalatable environment for real bird populations, essentially duplicating the effects of a live falcon.)
https://www.faa.gov/airports/airport_safety/wildlife/media/Wildlife-Strike-Report-1990-2015.pdf (USDA report on bird strikes from 1990 to 2015. The majority of aircraft which aborted take-off after a strike or near-strike were moving at speeds of 50-99 knotts, enough to cause severe damage to the aircraft on collision.)