What happened
On 19 October 2009, a Boeing 737-3Q8, registration G-OBMP, was performing a scheduled passenger flight from Ireland West Airport (EIKN) to Manchester. During the takeoff roll on Runway 09, the aircraft encountered a large flock of lapwings. As the crew reached the V1 speed and initiated rotation, the aircraft struck the birds head-on.
The impact caused immediate damage to both engines. The number 1 engine experienced significant bending and distortion of several fan blades, leading to increased vibration levels that reached up to 3.5 units during the climb. The number 2 engine suffered the loss of a portion of its acoustic panel, with fragments of the panel found on the runway. The cabin crew also reported unusual odors and significant vibrations throughout the left side of the aircraft. Following the encounter, the flight crew elected to divert to Shannon Airport (EINN), where the aircraft landed safely without further incident.
The investigation
The investigation by the AAIU focused on the nature of the engine damage and the airport's wildlife management procedures. Investigators confirmed that eight lapwing carcasses were recovered from the runway, and the total number of birds involved was estimated to be between 30 and 40.
Technical analysis of the flight data recorder (FDR) confirmed the spike in vibration on the number 1 engine. Maintenance inspections at Shannon revealed that the entire fan blade set of the number 1 engine required replacement due to the damage. On the number 2 engine, while two blades were slightly distorted, the damage was within allowable maintenance limits.
Regarding airport operations, the investigation found that no bird patrols had been conducted at EIKN for approximately two and a half hours prior to the departure. The Duty Controller had not requested a patrol because no bird activity had been observed earlier that day, and a previous departure had occurred without incident.
Findings
- The aircraft sustained multiple bird strikes from a flock of lapwings during takeoff.
- The number 1 engine suffered significant fan blade distortion, resulting in high vibration levels.
- The number 2 engine lost part of its acoustic panel due to the impact.
- The absence of a bird patrol in the two and a half hours preceding the flight contributed to the incident.
- The existing Manual of Air Traffic Services (MATS) provided the Duty Controller with too much discretion regarding when to request bird patrols.