Estimated reading time 3 minutes, 55 seconds.
Three-and-a-half years after the event occurred, the Canadian Department of National Defence Directorate of Flight Safety (DFS) has released the results of its investigation into the fatal crash of a CH-146 Griffon helicopter during a dustball takeoff in Afghanistan.
The accident occurred in July 2009, during a maximum-performance takeoff from a forward operating base in high-density-altitude conditions. During takeoff, the pilots of Griffon 434 lost visual references in dust and the aircraft drifted forward and right, striking a barrier and rolling onto its side. Although the pilots and one passenger managed to escape from the aircraft, two Canadian crewmembers and another passenger, a British soldier, perished in the ensuing post-crash fire.
The DFS investigation determined that the aircraft exceeded weight limits and that the crew attempted takeoff without knowing the helicopter’s available power. However, it also found that errors and omissions in critical operational and technical reference material precluded the crew from accurately conducting essential pre-flight calculations had they attempted to do so. Moreover, it found evidence of a systematic lack of understanding within the CH146 community at the time of how to correctly utilize performance data.
Additionally, the investigation determined that pilot training for operations in a degraded visual environment (DVE) was inadequate, and that the Griffon was deployed to Afghanistan without proper mitigation strategies for certain missions. Finally, limited amount of personnel in key headquarter positions contributed to inadequate planning support during the deployment preparation and planning phases, the report states.
The report notes that a number of safety actions were taken following the crash, including risk management activities, improvements to technical airworthiness processes, amendments to aircraft publications, changes to flight procedures and the creation of performance planning software (for more information, see “Expanded Capability” from Vertical’s Canadian Combat Helicopters in Afghanistan supplement). Flying orders were modified to require that all Griffon passengers be seated in approved seats with lap belts secured for takeoffs and landings, and the annual pilot examination was altered to address performance planning deficiencies.
However, the report also recommends additional preventive measures, including further training on performance planning and DVE operations; continued development of performance software planning tools or quick reference charts; evaluation of other displays, sensors and flight controls to improve the safety of DVE operations; and the creation of capability planning teams for major deployments.
The report also highlights that Canadian Forces (CF) rotorcraft are often operated according to different takeoff and landing procedures than the procedures assumed by the aircraft flight manual (AFM). The performance data in the AFM is valid only for specific procedures; if other procedures are used, the AFM data can be inaccurate or misleading and data that would be applicable is not available, it states. The report recommends reviewing aircraft performance data to ensure it is valid for CF operations, and to avoid new certification programs where AFMs could be developed with data that would not be used in the CF operational context.
