What happened
On September 12, 1998, at 10:25 local time, a Saab 340, registration SE-KPD, operated by Skyways AB, was performing a scheduled flight from Pori (EFPO) to Stockholm-Arlanda (ESSA). During the takeoff roll on runway 12, the aircraft encountered a large flock of birds just before reaching rotation speed. The flock, consisting of approximately 50 birds, descended into the path of the ascending aircraft, resulting in a collision.
The pilot immediately aborted the takeoff and informed air traffic control of the strike. The aircraft taxied back to the apron, where the crew and a maintenance technician inspected the damage. The inspection revealed a bent windshield wiper arm and biological debris across the airframe. A subsequent technical inspection in Stockholm also identified a crack in the radar dome. After the debris was cleaned and the aircraft was deemed airworthy, the flight was able to depart at 10:52.
The investigation
The investigation examined the movements of the birds and the visibility of the flock to air traffic control. It was established that the air traffic controller observed the flock from the left side of the runway just as the impact occurred, but was unable to issue a warning in time. Maintenance personnel at the airport had previously noticed the flock flying low near the runway, but did not witness the collision itself.
Investigators recovered 32 dead gulls and one hawk from the site. While a definitive species identification for the entire flock was not possible due to insufficient biological samples, the birds were identified as a mix of gulls and a hawk (possibly a Sparrowhawk or Eurasian Sparrowhawk). The investigation also looked into the presence of nearby water bodies, noting that a pond had been established near the airport in a manner that did not involve a formal consultation with the aviation authority.
Findings
- The primary cause of the collision was the panic-driven flight of a gull flock attempting to evade a pursuing hawk, which directed their flight path directly into the takeoff path of the aircraft.
- The pilot was unable to take evasive action as the birds were detected only at the moment of impact.
- The air traffic controller did not observe the birds prior to the strike and could not provide timely warning.
- The presence of a hawk likely triggered the sudden, low-altitude descent of the gull flock into the runway path.