What happened
On 20 February 2005, a Dorn and 328-100, registration G-BWIR, was operating a passenger flight from Edinburgh to London City Airport. During the landing on Runway 28, the aircraft experienced a significant loss of directional control shortly after touchdown. Despite the application of full left rudder, the aircraft began to veer to the right, eventually departing the paved surface and entering the grass area adjacent to the runway.
At the time of the incident, the airport was experiencing a crosswind of 13 knots from 330 degrees. The aircraft's flight data indicated that the nose-up pitch attitude maintained during the landing roll prevented the nosewheel steering system from engaging. The crew eventually regained control of the aircraft by utilizing asymmetric braking and asymmetric reverse thrust, successfully steering the aircraft back onto the runway and to its parking stand without any injuries to the 26 passengers or 3 crew members.
The investigation
The AAIB investigation examined the flight data recorder (FDR) and cockpit voice recorder (CVR) to reconstruct the sequence of events. Analysis of the FDR revealed that the aircraft's pitch attitude remained at approximately 1 degree nose-up during the period when the aircraft drifted off the runway. This was significant because the nosewheel steering system requires the noseleg weight-on-wheels (WOW) switch to be closed to function, a state that is prevented by an elevated nose attitude.
Engineers conducted tests on the aircraft's landing gear to examine the sensitivity of the WOW sensors. The tests confirmed that if the main landing gear legs are unloaded, the noseleg sensors may fail to detect ground contact if the aircraft maintains a nose-up attitude. The investigation also reviewed the aircraft's systems, finding no mechanical or system failures in the nosewheel steering or engine components.
Findings
- The initial deviation from the runway centerline was caused by a combination of crosswind and asymmetric reverse thrust.
- The nosewheel steering system was unavailable because the aircraft's nose-up pitch attitude prevented the noseleg weight-on-wheels switch from closing.
- The crew regained directional control only after the aircraft had left the runway by using differential braking and asymmetric thrust.
- There was no evidence of mechanical failure in the steering or engine systems.
Safety action
- The AAIB recommended that the Dornier 328 type certificate holder provide guidance to operators regarding post-touchdown elevator handling to ensure the nosewheel steering system is activated.