Windhoek accident report suggests low altitude stall

In a report compiled after concluding its probe of the fire-ball crash that killed three pilots during a flight testing mission, the directorate ruled out mechanical defects and other system malfunctions.

The report also indicated that the pilots also ignored or misinterpreted instructions from the control tower when they started a landing approach instead of circling and making a second landing approach.

The report said the aircraft hit the ground with its nose, resulting in a fire-ball that made it difficult to establish the position of the flight controls at the time of the impact.

Further, the report said an examination of the engines and mechanical components of the aircraft had concluded that they did not cause, or contribute to the accident.

The report said although there was no evidence of the pilots performing a training manoeuvre involving the simulation of loss of power from one of the engines during a landing approach, such high risk manoeuvres were common practice and could not be ruled out.

Most flight operations prohibit simulations of stalling engines unless when done on a flight simulator or at an altitude that is high enough to allow pilots to regain control should the aircraft stall or in the event of a pilot losing control.

The investigators said they could also not rule out an 'asymmetrical thrust scenario' in which one engine produces more thrust than the other, causing the aircraft to veer one direction and flip to the
under-powered side.

Among other recommendations, the directorate said the Namibia Civil Aviation Authority should prohibit the practice of simulating the loss of aircraft engine power during a landing approach, or restrict it to tests on flight simulators or at high altitudes to allow recovery should a stall occur.