Bird Strike on Final Approach: Guidance for Flight Crews
Bird Strike on Final Approach: Guidance for Flight Crews
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Editor's Note: This article discusses the issues and thought processes associated with a bird strike on final approach. Crews should follow company approved emergency procedures (e.g. Company Operating Manual) and manufacturers guidance regarding the conduct of the flight, and management of aircraft systems, when such an event occurs.
Description
This article provides specific guidance regarding the response to bird strike while on final approach.
In the context of this article "final approach" is defined as that period of flight following the final configuration necessary for landing.
Scenario 1
An aircraft is hit by birds while on final approach to land - should the pilot continue the approach or initiate a go around/missed approach?
Having encountered birds, the question to be answered is "what is the damage to the aircraft and what effect will this have on the safe conduct of the flight?".
The full extent of any damage, to the engines and/or the control surfaces and landing gear, may not be apparent until applying power, configuring, or manoeuvring the aircraft. It might therefore be the case that, if a go-around is initiated, the pilots rapidly find themselves in a situation where the runway is disappearing beneath them but the aircraft cannot safely fly a missed approach.
Therefore, in the above scenario, it is advisable to continue the approach and land.
Scenario 2
A pilot sees a flock of birds ahead of him on final approach - should he continue the approach or initiate a go-around/missed approach?
Having seen the birds, the question to be answered is "if a go-around is initiated, how likely is it that the aircraft will avoid a bird strike?".
There are two matters to consider. Firstly, the behaviour of birds towards an aircraft in flight is highly unpredictable and varies greatly by species, some waterfowl species typically dive but such behaviour is not consistent and the birds may fly upwards, potentially into the path of the aircraft initiating a go-around. Secondly, the greater the engine thrust, the greater the damage caused by ingesting birds - it is probable that less damage will be caused if the birds are hit while the engines are at low speed or idle.
Therefore, in the scenario described above, unless a go-around can be achieved with a reasonable degree of confidence that the aircraft will not hit birds, it is less hazardous to continue the approach to land.
Accidents and Incidents
Here are some examples of bird strike events, not necessarily on final approach, that have caused significant airframe or engine damage:
Significant Airframe Damage
On 19 November 2022, an Airbus A320 was descending below 13,000 feet towards its destination of Omaha, clear of clouds at night and at 290 knots, when an explosive decompression occurred as a result of bird strike damage. An emergency was declared, and once on the ground, three locations where the fuselage skin had been broken open were discovered. The structural damage was assessed as substantial, and the aircraft was withdrawn from service for major repairs. The birds involved were identified by DNA analysis as migrating Snow or Ross’s Geese, the former of which can weigh up to 2.6kg.
On 31 July 2012, a Boeing 737-900 struck a single large bird whilst descending to land at Denver in day VMC and passing approximately 6000 feet aal, sustaining damage to the radome, one pitot head and the vertical stabiliser. The flight crew declared an emergency and continued the approach with ATC assistance to an uneventful landing. The bird involved was subsequently identified as a White Faced Ibis, a species which normally has a weight around 500 gm but can exceptionally reach a weight of 700 gm. The hole made in the radome was 60 cm x 30 cm.
On 16 July 2010, a South African Express Airways Bombardier DHC 8-300 hit an animal during a night landing at Kimberley after a passenger flight from Johannesburg. The nose landing gear took a direct hit and collapsed but after a temporary loss of directional control, the runway centreline was regained and the aircraft brought to a stop. The Investigation found wildlife access to the aerodrome was commonplace and the attempts at control inadequate.
On 27 September 2012, a civil-operated Pilatus PC9 facilitating military target training for ground forces sustained structural damage to one wing when it struck an Osprey whilst at high speed and low level. The aircraft immediately became uncontrollable and the pilots did not have time to activate their ejector seats before the aircraft crashed and was destroyed. The Investigation noted that there were no relevant bird strike tolerance requirements for civil aircraft and attributed the accident systemically to use of such aircraft for target training and their operation at high speeds in airspace with a high bird strike risk.
On 4 August 2008, a Cessna 500 on a business charter flight encountered a flock of very large birds shortly after take off from a small Oklahoma City airport. Wing damage from at least one bird collision with a force significantly greater than covered by the applicable certification requirements made it impossible for the pilot to retain control of the aircraft. Terrain impact followed. Both engines also ingested a bird. The Investigation noted that neither pilot nor aircraft operator were approved to operate commercial charter flights but concluded that this was not directly connected to the loss of the aircraft.
Engine Damage
On 2 October 2021, an Airbus A320neo ingested a large bird into its right engine (a Pratt & Whitney PW1100G) during takeoff at Atlantic City and a high speed rejected takeoff followed. When leaked fuel pooling within the engine cowling subsequently ignited, an on-runway emergency evacuation was completed with the fire service in attendance. The Investigation identified the ingested bird as a bald eagle with a mass above the applicable certification standard and the fuel leak a secondary consequence of a fan blade broken by bird impact. Engine component design improvements to address the fire risk following large bird ingestion are being developed.
On 19 January 2013, a Rolls Royce Trent 700-powered Virgin Atlantic Airbus A330-300 hit some medium sized birds shortly after take off from Orlando, sustaining airframe impact damage and ingesting one bird into each engine. Damage was subsequently found to both engines although only one indicated sufficient malfunction - a complete loss of oil pressure - for an in-flight shutdown to be required. After declaration of a MAYDAY, the return to land overweight was completed uneventfully. The investigation identified an issue with the response of the oil pressure detection and display system to high engine vibration events and recommended modification.
On 26 September 2011, a Boeing 757-200 being operated by United Airlines on a scheduled passenger flight from Chicago to Denver experienced a left engine bird strike during deceleration after landing on runway 35R at destination in normal day visibility. The affected engine ran down as the aircraft cleared the runway and was shut down after a report of smoke being emitted from it. The aircraft was stopped and the remaining engine also shut down prior to a tow to the assigned terminal gate for passenger disembarkation. None of the 185 occupants were injured but the affected engine was severely damaged and there was visible evidence that some debris from it had impacted the aircraft fuselage.
On 29 July 2017, an Antonov AN-74 crew sighted several previously unseen large eagles rising from the long grass next to the runway as they accelerated for takeoff at Sao Tome and, concerned about the risk of ingestion, made a high speed rejected takeoff but were unable to stop on the runway and entered a deep ravine just beyond it which destroyed the aircraft. The Investigation found that the reject had been unnecessarily delayed until above V1, that the crew forgot to deploy the spoilers which would have significantly increased the stopping distance and that relevant crew training was inadequate.
On 10 November 2008, a Boeing 737-800 about to land at Rome Ciampino Airport flew through a large and dense flock of starlings, which appeared from below the aircraft. After the crew had made an unsuccessful attempt to go around, they lost control due to malfunction of both engines when full thrust was applied and a very hard impact half way along the runway caused substantial damage to the aircraft. The Investigation concluded that the Captain s decision to attempt a go around after the encounter was inappropriate and that bird risk management measures at the airport had been inadequate.
Further Reading
Bureau d’Enquêtes et d’Analyses - France
UK CAA
Other
- Strategies for prevention of bird strike events, R. Nicholson, W. Reed, Boeing AERO magazine, Q3 2011.
