What happened
On 2 June 2002, an Aero Vodochly L-39C Albatros, registration G-BZVL, was conducting a conversion training flight when it experienced a critical failure during landing at Duxford Airfield. The aircraft, operated for a private flight, touched down on Runway 06 as planned. However, during the landing roll, the crew discovered that the normal wheel brakes were non-functional. Despite attempts by both the student pilot and the instructor to apply braking, the aircraft failed to decelerate.
As the aircraft approached the end of the runway, the instructor used the rudder to steer the jet towards open ground to avoid the adjacent M11 motorway. During this excursion, the instructor instructed the student pilot to retract the landing gear. The aircraft eventually breached the airfield boundary fence and descended onto the M11 motorway. During this sequence, the student pilot initiated an ejection. Because the aircraft was traveling at a low speed and in a downward trajectory, the parachute did not have sufficient time to fully deploy, resulting in 1 fatality and 1 uninjured crew member.
The investigation
The AAIB investigation focused on the failure of the braking system and the subsequent emergency actions. Investigators examined the hydraulic and braking mechanisms, noting that the normal braking system relies on a microswitch on the nose landing gear to allow brake application only when the weight is on the wheels. While the investigation could not replicate the failure, it was noted that the instructor's previous experience with the Hawk trainer—which lacks an emergency brake system—may have influenced his decision-making.
Testing of the G-BZVL braking systems showed no anomalies, but the investigation highlighted that the instructor did not utilize the available emergency brake lever. Furthermore, the investigation looked into the ejection sequence, confirming that the student pilot's ejection occurred below the minimum speed required for a safe, fully functional parachute deployment at ground level.
Findings
- The primary cause of the runway excursion was the failure of the normal wheel brakes to provide deceleration.
- The instructor failed to employ the emergency braking system, which was available in the L-39C.
- The instructor's instruction to retract the landing gear was ineffective because the system inhibits retraction while the nose wheel is on the ground.
- The student pilot initiated ejection at a speed below the 150 km/hr threshold required for a safe ground-level ejection.
- The lack of engine shutdown prevented the use of engine thrust reduction to assist in deceleration.
Safety action
- The CAA was advised to review runway overrun protection at Duxford to prevent incursions onto the M11 motorway.
- It was recommended that L-39 operators include emergency brake usage in their training syllabuses.
- A recommendation was made to require aircraft with live ejection seats to carry the necessary safety pins for the escape systems during all flights.