Investigators have determined that a non-rated pilot inadvertently activated the lift dump on a Beechcraft Premier I business jet during final approach to Subang, causing it to lose height and crash short of the runway.
None of the six passengers and two pilots survived. Two motorists were also killed when the Jet Valet aircraft came down on a highway, 2.7nm from the threshold of runway 15, on 17 August last year.
Malaysia’s Air Accident Investigation Bureau states that the captain of the aircraft – who was the flying pilot – held a single-pilot rating for the jet, and had just under 37h on type.
But he was sat in the right-hand seat, in contravention of single-pilot procedures which mandated sitting in the left seat, for optimal access to controls.
The other pilot, serving as second in command, was rated on the Gulfstream IV business jet but not the Premier I.
“This lack of rating suggests that [he] might not have been fully trained or familiar with the systems and procedures of the [aircraft],” says the inquiry.
“Proper training and familiarity with the aircraft type are crucial for effective performance and safety.”
The aircraft, arriving from Langkawi, was conducting an NDB approach to Subang’s runway 15.
According to the inquiry the captain instructed the other pilot on certain systems, including navigation, flight controls and communications.
Cockpit-voice reorder information shows that, along with carrying out monitoring duties, the second pilot operated systems including the flaps, landing-gear and spoilers during checklist readings.
The ‘before landing’ checklist includes an item requiring the lift dump to be unlocked, but also features a specific warning that the lift dump must not be activated in flight.
At about 1,000ft, as the second pilot read the checklist item – stating “lift dump unlocked, handle illuminated” – the captain acknowledged, remarking “lift dump unlocked”.
But about 1.7s later several alarms sounded in the cockpit, including the lift-dump warning, autopilot disconnect, and ‘sink rate’ and ‘pull up’ alerts.
The inquiry says there is a “high probability” that the second pilot “inadvertently extended the lift dump” while performing the checklist.
Pulling the lift-dump handle would have transmitted a signal to extend all six spoiler panels, causing the jet abruptly to lose lift.
As the aircraft rapidly descended, the crew unsuccessfully attempted to regain control. Less than 15s after the lift-dump activation, the jet crashed onto the central median of a highway in the Elmina district and disintegrated.
Analysis of cockpit instrumentation, including through computed tomography scans, “conclusively determined” that the lift-dump handle – located on the left side of the central pedestal – was in the extended position, says the inquiry, and all spoilers had extended prior to the crash, leading to a “catastrophic loss of control”.
