Report on fatal Griffon crash in Zabul province

Further to this post, the official text:

Flight Safety

Occurrence Report

CH146434 Griffon

Date: 6 July 2009
Location: Forward Operating Base (FOB), Afghanistan

From the Investigator (FTI) (pdf 81 kb) Posted 2009-09-09

From the Investigator:

The accident involved a CH146 Griffon helicopter deployed in Afghanistan as part of the Joint Task Force (Afghanistan) Air Wing. The crew consisted of two pilots, one Flight Engineer (FE), and one Door Gunner (DG). Two passengers were also onboard; one Canadian and one coalition soldier.

The mission was to bring four passengers to a Forward Operating Base (FOB) in Afghanistan. Two CH146 Griffons were tasked, carrying two passengers each for insertion in the morning and again for extraction in the afternoon. The morning portion of the mission was conducted without incident. The accident occurred during the afternoon extraction.

The accident aircraft was the second aircraft in the formation. The lead aircraft was the first to land and pick-up its two passengers. On take-off the lead aircraft cleared the HESCO barrier on departure by approximately ten feet, and informed the other crew that maximum power available would be required. A HESCO barrier is a fabric-lined metal mesh structure filled with sand and gravel. The second aircraft conducted the landing succesfully and picked up the two remaining passengers.
In consideration of the information passed by the lead aircraft, the occurrence crew developed their take-off plan. The take-off would be executed in two phases: a max performance take-off to maximize vertical obstacle clearance followed by an Instrument Take-off (ITO) once visual ground references were lost. The Flying Pilot (FP) pulled collective to 95% mast torque for the max performance take-off. Conscious of the high temperature of the day, just above 40oC, the FP gave a quick crosscheck to the InterTurbine Temperature (ITT) guage and noted a reading of 840-850oC. At that moment the Non-Flying Pilot (NFP) looking at the visual ground references, called “Drifting Right”. The FP’s attention was immediately redirected outside to reaquire visual ground references, but a dust ball had obscured all visual cues, so the FP transitioned to instrument references to fly the helicopter. The NFP made a second “Drifting Right” call, but just as the word “Right” was spoken, the aircraft hit the HESCO barrier.

The aircraft hit the barrier at the one to two o’clock position (relative to the aircraft), breaking the righthand pilot’s windscreen. The impact point was between the aircraft nose and forward of the right pilot door. On impact, the tail pitched up and simultaneously the aircraft rotated approximately 90 degrees counter-clockwise and rolled onto its right side, catching fire almost immediately. One pilot was uninjured and the other suffered only minor injuries, so they were able to evacuate the aircraft through the shattered windscreen. The Canadian passenger, despite serious injuries, followed the pilots out. The two pilots attempted to provide assistance to the personnel still inside the helicopter, but the post-crash fire precluded them from rendering assistance. The coalition soldier, the FE, and the DG perished in the accident.

A number of preventive measures have been recommended and are in the process of being implemented, including:

• Improved procedures for Operations in Brown-out
• More detailed instructions for pre-flight calculations
• Technical evaluation of aircraft performance charts for pre-flight planning
• Evaluation of seating requirements for various mission profiles, and

Evaluation of the descriptions given in the Standard Manoeuvre Manual for Max-Performance and Instrument take-off Procedures.

No pertinent technical deficiencies have been discovered to date. The investigation is focusing on Human Factors, Desert Operations, and obscuring phenomena. Rear cabin evacuation and survivability are also under investigation.