Accidents
Loss of Hermes 450
Summary:
Whilst attempting an automatic landing the Unmanned Air System (UAS) self-aborted. This abort was due to an incorrect set-up parameter that had been loaded by the crew. The crew elected to intervene rather than let the UAS self-recover. The air vehicle hit a new, unoccupied hangar; it was ultimately deemed ?non-repairable?.
Details:
On 2 October 2011, a Hermes 450 UAS crashed at Bastion Airfield, Afghanistan. The aircraft was unrepairable.
The aircraft sortie was terminated early due to rising engine temperature. Due to the presence of vehicles and people in the vicinity of the runway, the GPS Take Off and Landing System (GTOLS) was selected to land the aircraft. Shortly after the approach had been initiated, the landing was self-aborted by the UAS. This abort occurred as a result of an incorrect data parameter in the GTOLS set-up loaded by the crew.
Moments after the self-abort, due to the urgency of the situation and the addition strain on the engine caused by the aborted landing, the crew chose to abbreviate the pre-programmed go-around GTOLS route. Instead, they issued a ‘fly to coordinate’ command. As the aircraft was climbing, the engine temperature rose rapidly, before the engine failed completely. On its descent the aircraft initially impacted an unoccupied hangar, before striking the ground upside down. It eventually came to rest on an empty aircraft dispersal pan.
The Service Inquiry determined that the cause of the accident was engine failure, as a result of overheating caused by oil starvation. Like many incidents, there were a considerable number of interacting factors. In total, thirteen contributory factors were identified, including the error in the GTOLS data.
This incident highlights the importance of the integrity Data Property, with respect to the GTOLS data loaded by the crew.
Links
https://www.gov.uk/government/publications/service-inquiry-investigating-the-accident-involvingunmanned- air-system-uas-hermes-450-zk515-on-02-oct-11
(accessed 29 November 2017).