What happened
On 1 March 2008, a Boeing 747-412 cargo aircraft, registration B-KAG, was performing a scheduled flight from Dubai to Manchester Airport. During the initial approach to Runway 23R, the crew encountered a windshear warning at 500 ft, prompting a missed approach. Following radar vectors, the crew attempted a second approach using a flap 25 setting.
As the aircraft neared the runway, it was subjected to intense wind fluctuations. While the aircraft was stable for much of the approach, the descent rate and glideslope stability were compromised just before touchdown. The aircraft experienced a sudden loss of 20 kt of airspeed followed by a rapid 23 kt gain. During this period, the aircraft drifted from the right of the localiser to 15 metres left of the runway centreline.
Upon touchdown, the aircraft experienced a significant right roll of 9.7°, which caused the No 4 engine nacelle to strike the runway surface. This was followed by a left roll that caused the No 1 and No 2 engine nacelles to also make contact with the runway. Additionally, the No 2 tyre on the left main landing gear ruptured during the rollout.
The investigation
The AAIB examined flight data recorder (FDR) and cockpit voice recorder (CVR) data, alongside an inspection of the aircraft and the runway. The investigation focused on the wind conditions, the aircraft's flight path, and the mechanical state of the landing gear.
Analysis of the runway revealed scrape marks consistent with the nacelle strikes. The investigation also identified a fault in the No 2 anti-skid control valve, which had caused the No 2 tyre to lock during braking, leading to the tyre rupture. However, the investigation found no evidence of crew fatigue or improper aircraft configuration.
Findings
- The landing conditions were challenging, with crosswinds approaching the operator's limits.
- Significant variations in wind direction and speed occurred immediately prior to touchdown, causing the aircraft to drift and deviate from the glideslope.
- The aircraft's roll to the right at touchdown was sufficient to cause the No 4 engine nacelle to contact the runway.
- The No 2 tyre rupture was caused by an inoperative anti-skid control valve that allowed the wheel to lock during the ground run.