What happened
On 12 February 2002, at approximately 0600 Z, a commercial HS-125-400B, registered as ZS-JBA, was parked on the international departures apron at Lanseria (FALA). The aircraft was prepared for a scheduled flight to Blantyre, Malawi.
During the pre-departure phase, the pilot initiated internal pre-start checks while the co-pilot boarded passengers. After the passengers were onboard, the co-pilot closed the aircraft door and began the passenger briefing. At this time, the co-pilot removed the wheel chocks. Immediately following the removal of the chocks, the pilot observed the aircraft rolling forward. Despite efforts to halt the movement, the aircraft continued to roll, narrowly avoiding a hangar and a parked Bell Long-ranger helicopter. The movement ended when the aircraft crossed the taxiway and came to a rest in a ditch located between the taxiway and the runway. There were no injuries and no fatalities resulting from the incident.
The investigation
The investigation focused on the state of the aircraft's braking system and the pre-flight procedures followed by the crew. Investigators examined the hydraulic system and found its operation to be satisfactory. It was determined that the brakes could be applied successfully once the hand pump was used to pressurize the system.
Findings
- The pilot proceeded with pre-flight checks under the assumption that the engineer had already pressurized the hydraulic accumulator, which led to the pilot omitting a personal inspection of the pressure levels.
- The hydraulic system was not pressurized during the pre-flight inspection.
- Because the system lacked adequate pressure, the brakes were ineffective once the chocks were removed.