PALMER, AK, USA
N7370N
Cessna 206
The float equipped airplane was reported by the pilot to be in cruise flight about 800 feet above the surface of a glacier. He estimated the gross weight of the airplane at 3,312 pounds. He was flying in an up-glacier direction, in a mountainous valley. The prevailing winds at the surface were reported by the pilot to be 15 knots in a down-glacier direction. The pilot stated that the airplane began to descend rapidly, and that full power did not arrest the descent. The Cessna U206G performance charts indicate a climb rate between 915 and 1,005 feet per minute given the prevailing conditions. The pilot said there were no mechanical problems with the airplane, and that he did not attempt to turn because the most favorable landing terrain was ahead of the airplane. The airplane collided with slightly rising terrain, in a wings level, nose up attitude, just as the stall warning horn activated. The airplane sustained substantial damage. There were no injuries to the four occupants.
On July 18, 1998, at 1828 Alaska daylight time, a float equipped Cessna 206 airplane, N7370N, sustained substantial damage when it collided with terrain about 3,000 feet msl at 61 degrees 24.38 minutes North latitude, 148 degrees 14.09 minutes West longitude. The commercial pilot and the three passengers were not injured. The flight was operated under 14 CFR Part 91 as a personal flight to view glaciers. The flight departed from Six Mile Lake Seaplane Base, Anchorage, Alaska, at 1755. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The pilot told the NTSB investigator-in-charge (IIC) during a telephone interview on July 18, 1998, that while cruising at 95 knots, in an up glacier direction about 700 feet above the glacier surface, the airplane began to descend rapidly. The pilot stated he added power, but was unable to arrest the descent before colliding with slightly rising terrain near the glacier's edge. The pilot indicated that he did not attempt to turn because the most favorable landing terrain was ahead of the airplane. He said in the interview, and wrote in his pilot/operator report, that the winds on the surface were flowing down the glacier approximately 15 knots, and the temperature was 55 degrees Fahrenheit. The pilot calculated the airplane's weight to be 3,312 pounds. The Cessna Model U206G rate of climb table shows a maximum rate of climb at 3,300 pounds and 2,000 feet pressure altitude, given a temperature between 0 and 20 degrees C, to be between 915 feet per minute (fpm) and 1,005 fpm.
The pilot's inadequate compensation for wind conditions, and inadequate clearance from mountainous terrain. Factors were the downslope winds and downdrafts.
Source: NTSB Aviation Accident Database
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