What happened
On 27 April 2008, an Airbus A340-313, registration G-VAIR, was performing a commercial passenger flight from London Heathrow to Nairobi. During the final approach to Runway 06, the crew encountered deteriorating visibility due to localized fog. As the aircraft transitioned through the flare phase, the pilot flying experienced a loss of visual references, specifically losing sight of the right side of the runway and the runway lights.
In response to the loss of visual cues, the pilot applied left rudder pedal input, causing the aircraft to drift laterally. Although the commander initiated a go-around, the aircraft touched down with the left main gear already deviating from the centerline. The left main gear ran off the paved surface and traveled approximately 180 metres along the edge of the runway. The crew successfully applied corrective rudder and advanced the thrust levers to full power, allowing the aircraft to become airborne again after a brief period on the ground. There were no fatalities and no injuries to the 14 crew members or 108 passengers on board.
The investigation
The investigation examined the aircraft's flight data, the runway surface condition, and the airport's lighting infrastructure. Investigators found that the runway surface at the touchdown zone was heavily contaminated with rubber deposits, which could potentially reduce friction. Furthermore, the investigation identified that the runway edge lights were positioned 7.5 metres from the edge of the paved surface, which deviates from the ICAO standard of a maximum 3-metre distance.
Analysis of the Automated Weather Observation System (AWOS) showed that the Runway Visual Range (RVR) had dropped significantly, reaching as low as 550 metres around the time of the incident. The investigation also noted that while the system recorded these changes, the tower controllers had not been specifically trained on the use of the AWOS and relied on pilot reports and periodic METAR updates.
Findings
- The primary cause of the excursion was the pilot flying's left rudder pedal input following the loss of visual references.
- Localized changes in fog density and the variability of the quality of runway lighting contributed to the loss of visual cues.
- The runway edge lighting was not in compliance with ICAO standards regarding its distance from the runway edge.
- Significant rubber deposits were present on the runway surface, which may affect braking effectiveness.
- The airport's lighting maintenance and the training of air traffic controllers on the AWOS were identified as areas for improvement.