Manual navigation by Canadian army controllers blamed
The Canadian army's loss of two Sperwer tactical unmanned air vehicles continues to be investigated, with the Department of National Defence and Sagem releasing new details of a 21 January crash into a mountain ridge bisecting the Afghan capital Kabul.
Laughlin Trowsdale, air support safety co-ordinator for UAVs in the DND's surveillance systems project office, says the air vehicle was under manual control when it crashed. The accident occurred "in the landing sequence and the crew did not recognise the mountain. They did not respond to the ground alert alarms, within the ground control station," he says. "The air vehicle commander [was] a licensed pilot at the time of the accident."
Sagem was appointed to undertake analysis of all available flight data leading up to the crash. That analysis has "proved that the air vehicle was not on autonomous navigation and flight plan. It had been put in manual navigation, which is by high-level [command] of heading and altitude.
"For some reason, which is not explained yet, at one moment the crew decided to quit the normal approach altitude, which was published for operation in that area, and to descend heavily at that moment under manual control. It is at that moment that the flight went into terrain," says Sagem.
"We do not know exactly why this manual order was given. But the system is fitted with alarms, ringing and showing up on the ground control station [displays]. The post-flight analysis proved they had been active for 30s with red alarms on before the controlled flight into terrain," he says.
Details remain scarce on the 21 November 2003 loss of an air vehicle over Kabul, with an accident report to take up to another year to complete. An investigation team is continuing to examine why the air vehicle parachute recovery system failed in the final stages of a trials flight.
Trowsdale says Sperwer will be withdrawn from Afghanistan in third quarter of this year.
Source: Flight International
