Altimeter setting suspected in fatal Cat Lake air crash

A report on the crash of a Lockhart Air Cessna 3-10 near Cat Lake First Nation last November indicates that an incorrectly set altimeter may have played a primary role, says the Transportation Safety Board of Canada.

Dryden-based pilot Michael Pateman and Cat Lake residents Ronald Ombash and Dean Meekis were killed, Nov. 6, 2009, when the plane collided with rising terrain approximately 15 kilometres southwest of the Cat Lake airport. The flight originated in Sioux Lookout at around 6 p.m.

In its investigation, the Transportation Safety Board of Canada (TSBC) found that the aircraft’s altimeters were likely set incorrectly, resulting in a higher reading that led the pilot to descend below a safe altitude – a mistake that is much less noticeable on the ‘three-pointer’ style altimeters used in that particular aircraft.

Between the aircraft’s last flight before the accident on Nov. 5, the TSBC found a one-inch barometric pressure change in the altimeter setting, a factor that would change the altimeters’ reading by approximately 1,000 feet.

The report reads: “In total darkness, with no visual cues, the pilot would have to rely solely on his altimeters to determine his altitude. A 1,000 foot error could be more difficult to detect with the three pointer type of altimeter installed on the occurrence aircraft because the longer pointers (the ones most often referenced) would be in a similar position at either setting. As a result, the pilot likely did not notice the incorrect altimeter settings and during the downwind leg, descended to terrain height believing that he was descending to circuit altitude.”

At the crash site, investigators found that the degree of damage to trees (over a distance of 275 metres) indicated that the engines were producing power and the aircraft was operating at significant speed at impact.

“This, coupled with the wings-level shallow descent angle at which the aircraft contacted the trees, indicates that the aircraft was likely operating normally and under control of the pilot at impact,” read the report.

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