Description

On 19 October 2009, a Boeing 737-300 being operated by British Midland subsidiary bmibaby on a scheduled passenger flight from Knock (also more recently known as ‘Ireland West’) to Manchester encountered a large flock of medium-sized birds during rotation for take off in normal day visibility and engine malfunction followed. Increasing engine vibration during the climb led to the decision to divert to Shannon, which was completed without further event. There were no injuries to the 133 occupants or anyone on the ground.

Investigation

An Investigation was carried out by the Irish AAIU. Flight Data Recorder (FDR) data was available to assist the Investigation. Damage to No 1 engine was found to have been significant but damage to No2 engine only minor. Some engine debris was found near the site of the encounter.

The Investigation established that although birds had passed down both sides of the aircraft, increases in engine vibration had been mainly in respect of engine No 1. Initially these indications, whilst abnormal, had remained well within the band that requires no crew action and although they had increased as the aircraft climbed from FL70 to FL100, they remained below 4 on the five point scale, which is the level where Quick Reference Handbook (QRH) drills become applicable and normal use of engine thrust had therefore been maintained throughout the flight. It was apparent that most of the debris from No 1 engine had bypassed the engine core after passing through the fan blades.