What happened
On 14 December 1999, at approximately 17:38 UTC, a Piper PA-34-200T, registration G-BEAG, was involved in a ground collision at Oxford Airport. The aircraft was being prepared for a night training session by an instructor and two student pilots, one of whom was seated in the rear as an observer.
Following a pre-flight inspection where the parking brakes were tested and appeared functional, the crew boarded the aircraft. During the engine start sequence, the student pilot released and reapplied the parking brakes. While the instructor was monitoring the cockpit interior during the start of the engines, the aircraft began to yaw violently to the left. The instructor immediately closed both throttles to stop the movement. The aircraft had struck a parked, unattended PA-28, registration G-BODC.
The investigation
The investigation established that the left engine stopped following the impact, and the right engine was shut down immediately. Upon inspection, the instructor noted that while the parking brake was engaged, an additional 1/4 inch of movement was possible when re-applying it. The impact from the left propeller caused damage to the rudder and tail cone of the PA-28, while the right propeller damaged the parked aircraft's right aileron. There were no injuries to the crew or the passenger.
Findings
- The aircraft moved forward during the engine start process because the parking brakes were not fully applied.
- The pilot noted that the brake pedal often requires several pumps to achieve full application, a step that may not have been sufficiently completed during the student's brake check.
- The instructor did not perceive the movement through visual or physical cues until the sudden yawing occurred, partly due to the low-light conditions of the night preparation.