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.
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.
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 finds 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.
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
- B734, Amsterdam Netherlands, 2010 (1) (On 6 June 2010, a Boeing 737-400 being operated by Atlas Blue, a wholly owned subsidiary of Royal Air Maroc, on a passenger flight from Amsterdam to Nador, Morocco encountered a flock of geese just after becoming airborne from runway 18L in day VMC close to sunset and lost most of the thrust on the left engine following bird ingestion. A MAYDAY was declared and a minimal single engine climb out was followed by very low level visual manoeuvring not consistently in accordance with ATC radar headings before the aircraft landed back on runway 18R just over 9 minutes later.)
- B734, Barcelona Spain, 2004 (On 28 November 2004, a KLM B737-400 departed laterally from the runway on landing at Barcelona due to the effects on the nosewheel steering of a bird strike which had occured as the aircraft took off from Amsterdam.)
- B738, Djalaluddin Indonesia, 2013 (On 6 August 2013, a Boeing 737-800 encountered cows ahead on the runway after landing normally in daylight following an uneventful approach and was unable to avoid colliding with them at high speed and as a result departed the runway to the left. Parts of the airport perimeter fencing were found to have been either missing or inadequately maintained for a significant period prior to the accident despite the existence of an airport bird and animal hazard management plan. Corrective action was taken following the accident.)
- B739, en-route, east of Denver CO USA, 2012 (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.)
- B763, vicinity London Heathrow UK, 1998 (On 1 September 1998, a Boeing 767-300 had a bird strike with a large flock of geese moments before touchdown at London Heathrow airport, causing substantial damage.)
- C172, McKinney TX USA, 2003 (On 8 July 2003, a Cessna 172S on an instructional flight hit a vulture which caused significant structural damage to the left wing. During the attempted forced landing which followed, control of the aircraft was lost and the aircraft crashed into terrain near McKinney TX USA.)
- A320, vicinity Auckland New Zealand, 2012 (On 20 June 2012, the right V2500 engine compressor of an Airbus A320 suddenly stalled on final approach. The crew reduced the right engine thrust to flight idle and completed the planned landing uneventfully. Extensive engine damage was subsequently discovered and the investigation conducted attributed this to continued use of the engine in accordance with required maintenance procedures following bird ingestion during the previous sector. No changes to procedures for deferral of a post bird strike boroscope inspection for one further flight in normal service were proposed but it was noted that awareness of operations under temporary alleviations was important.)
- A320, vicinity Delhi India, 2017 (On 21 June 2017, an Airbus A320 number 2 engine began vibrating during the takeoff roll at Delhi after a bird strike. After continuing the takeoff, the Captain subsequently shut down the serviceable engine and set the malfunctioning one to TO/GA and it was several minutes before the error was recognised. After an attempted number 1 engine restart failed because an incorrect procedure was followed, a second attempt succeeded. By this time inattention to airspeed loss had led to ALPHA floor protection activation. Eventual recovery was followed by a return to land with the malfunctioning engine at flight idle.)
- A320, vicinity LaGuardia New York USA, 2009 (On 15 January 2009, a United Airlines Airbus A320-200 approaching 3000 feet agl in day VMC following take-off from New York La Guardia experienced an almost complete loss of thrust in both engines after encountering a flock of Canada Geese . In the absence of viable alternatives, the aircraft was successfully ditched in the Hudson River about. Of the 150 occupants, one flight attendant and four passengers were seriously injured and the aircraft was substantially damaged. The subsequent investigation led to the issue of 35 Safety Recommendations mainly relating to ditching, bird strike and low level dual engine failure.)
- A333, vicinity Gold Coast Queensland Australia, 2017 (On 3 July 2017, an Airbus A330-300 was climbing through 2,300 feet after a night takeoff from Gold Coast when the number 2 engine began to malfunction. As a cabin report of fire in the same engine was received, it failed and a diversion to Brisbane was made. The Investigation found that the engine failure was entirely attributable to the ingestion of a single medium-sized bird well within engine certification requirements. It was concluded that the failure was the result of a sufficiently rare combination of circumstances that it would be extremely unlikely for multiple engines to be affected simultaneously.)
- A333, vicinity Orlando FL USA, 2013 (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.)
- AN72, Sao Tome, Sao Tome & Principe, 2017 (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.)
Bureau d’Enquêtes et d’Analyses - France
- Strategies for prevention of bird strike events, R. Nicholson, W. Reed, Boeing AERO magazine, Q3 2011.