Inadequate Speed Led To Inadvertent Stall

The NTSB has issued its Probable Cause report on the downing of a Pilatus PC-12 near Big Timber, MT in June 2006.

As ANN reported, a former Microsoft executive and his pilot were killed when their single-engine turboprop crashed shortly after takeoff. Jeffrey M. Harbers was receiving flight instruction from 31-year-old Jason Barton at the time of the accident.

According to the Probable Cause report, "the airplane was observed, on radar, to make a "very rapid descent" towards the runway at Lavina, from approximately 12,000 feet." Another PC-12 flight instructor said this maneuver looked like a practice for emergency descent training.

Air traffic controllers reported "radar contact was lost for approximately 3 minutes" and when radar contact was reacquired, the aircraft was about 4 nm west of the Lavina airport. ATC then said the PC-12 continued southwest, and its last radar contact was at 1226.

A witness told investigators  "the aircraft seemed to be recovering, but the elevation of the adjacent ridge was rising rapidly in relation to the aircraft's direction. At the last few seconds, the aircraft was able to pitch up in what appeared to be a landing flare."

The witness then reportedly observed dirt and grass flying up behind the aircraft, saying "the airplane's right wing tip and engine impacted terrain."

Harbers, 54, led engineering and development work on Microsoft's Office software program during the 1980s, according to friend and former Microsoft co-worker Jeff Raikes. He also served as director of Microsoft applications development, before leaving the company in the early 1990s to devote his time to environmental causes.

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