What happened
On 29 October 2002, a Boeing 767-304, registration G-OBYB, arrived at Birmingham International Airport from Manchester on a positioning flight. The aircraft, carrying nine crew members and no passengers, performed a standard approach to Runway 15. The landing was initially normal, with the aircraft touching down firmly within the touchdown zone and decelerating as expected.
After the groundspeed had reduced to approximately 65 kt, the crew released the brakes and cancelled the use of thrust reversers. The aircraft continued along the runway toward a left-hand turnoff located at the far end of the paved surface. As the aircraft approached the threshold of the reciprocal runway, the crew applied gentle braking. However, when the aircraft attempted to initiate the turn at approximately 40 kt using rudder and differential braking, it failed to complete the maneuver. The nosewheels exited the paved surface, traveling roughly 15 metres onto the unpaved area before the aircraft came to a halt. The main landing gear remained on the runway, and there were no injuries to the crew.
The investigation
Investigators analyzed data from the aircraft's flight recorders, including the Digital Flight Data Recorder and the Cockpit Voice Recorder. The analysis revealed that while the initial landing and deceleration were stable, the aircraft's deceleration decreased significantly just before the turn was initiated, despite an increase in symmetric brake pressure.
Subsequent friction testing of the runway surface was conducted. While the overall friction levels were found to be high, investigators identified specific areas near the threshold markings where the friction coefficient had dropped into the maintenance planning band. It was noted that the presence of drizzle at the time of the incident may have further reduced the effective friction in these specific patches.