MCDONNELL DOUGLAS HELICOPTER 600N near Delta Junction, AK — 2012-08-08

Probable cause

The pilot’s failure to clear the left landing gear skid, which resulted in the entanglement of the left landing gear skid with a log, and his subsequent application of collective pitch, which resulted in a dynamic rollover.

NTSB narrative

The pilot was transporting personnel from a remote elevated helipad constructed of logs. Witnesses stated that the helicopter had just touched down, and the pilot turned his head to give the signal to board when the helicopter suddenly pitched up and back, striking trees at the edge of the helipad. The helicopter rolled down the hill. A postaccident examination of the helipad revealed that one of the logs that made up the rear portion of the helipad decking had been pulled from the structure and damaged. Based on the lack of mechanical anomalies with the helicopter and the damage to the helipad decking, it is likely the pilot landed too far forward on the helipad, which allowed the tail of the left skid to fall into the open area between the logs and become entangled. It is likely that the pilot sensed the imbalance and applied collective pitch, which resulted in a dynamic rollover.

Analysis

Primary failure mode

Controlled flight into terrain

First missed decision gate

Pilot could have chosen a different landing approach to avoid terrain strikes.

NTSB coding

• Dynamic rollover · Landing-aborted after touchdown
• Decision Making / Judgment

Evidence available

• Photos
• 8 docket documents

Docket documents8

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form
• Statement of Party Representatives to NTSB Investigationinterview
• Witness Statementsinterview
• GPS 17 - Attachment 1 - Tabular Data(CSV)other
• GPS 17 - Specialist's Factual Report (4 Embedded Images)photos
• Photo 1 - Remote helipad at Rig 3.photos
• Photo 2 - Helicopter wreckage.photos
• Toxicological Reportreport