Mountain Wave
Overwhelms Lancair ES Pilot
The dangers on the downwind side of large mountains
BY J. MAC MCCLELLAN
UNTIL RECENTLY INVESTIGATORS TRYING to determine the probable
cause of fatal general aviation accidents had little more than maybe
an eyewitness or an air traffic radar plot to describe the final
moments of flight. But now several flat glass primary flight display
(PFD) systems designed both for normal category and experimental
amateur-built airplanes can record and preserve key parameters of
flight much the same as a flight data recorder does in a large jet. A
Lancair ES that broke apart in flight downwind of Mount Rainier
had such a PFD that recorded its flight path to disaster.
It was summer when the pilot/builder of the Lancair and a passenger departed Ketchikan, Alaska, on an IFR flight to Mountain Home,
Idaho. The high-performance kit airplane was powered by a
Continental IO-550 engine and had flown 266 hours since it received
its AB airworthiness certificate four years earlier. The pilot was instrument rated with more than 590 hours of total experience, and 176
hours of simulated instrument flying experience. He had logged only
four hours of flying in actual instrument meteorological conditions.
The pilot received a standard weather briefing and filed his IFR
flight plan in the morning before departing Ketchikan. The overall
weather situation showed a cold front extending from a low pressure
system over Canada just north of the Washington and Idaho borders.
The coastal section of Washington state was forecast to have low
overcast ceilings of around 600 feet with marginal VFR conditions
farther inland. Good VFR was forecast for all of central and eastern
Washington and Oregon.
The forecasts gave the Lancair pilot good reason to believe he
would be flying on top of overcast clouds en route and then have
VFR conditions for his arrival at Mountain
Home. The winds aloft forecast for the
Lancair’s cruise altitude predicted winds
from 245 degrees at 27 knots with an air
temperature of minus 1 degree Celsius. That
wind forecast indicated a chance of light to
moderate turbulence.
