Friday, February 13, 2015

Fatal crash of helicopter was due to lack of clear communication

Words matter.

On November 6, 2014 at about 7:00 PM an AH-64D Apache Longbow attack helicopter (like the one shown above) crashed south of Gowen Field (the Boise Airport) in the dark. Both Idaho National Guard pilots, who were senior flight instructors and Chief Warrant Officers, were killed. Last Monday results summarizing the Army accident investigation concluding that it was caused by pilot error were reported in the Idaho Statesman (and Stars and Stripes). You can watch a YouTube video of Colonel Tim Marsano.

Jon Hartway was getting his annual flight evaluation from Stien Gearhart. Part of that was simulating a loss of power to one of the two gas turbine engines. That was to be done by briefly moving a throttle into the “lock-out” position, which disconnects an engine from the transmission that drives the rotor. It is like moving the shift lever of a car with an automatic transmission from Drive to Neutral while still pressing down on the accelerator pedal.

Investigators concluded that instead both throttles were pushed to the lock-out position, and held longer than they should have been. When both turbines began to overspeed, they automatically shut down. So, the helicopter was without power while only 400 feet above the ground. They had only three seconds before impact. It wasn’t possible to determine who locked out which engine. 

But, there had to be a lack of clear communication leading to a tragic misunderstanding. One pilot was in front of the other (not side by side) so they could not directly see what the other was doing with their pair of throttles. 

An image of an Apache helicopter came from Wikimedia Commons.

No comments: