Flight Details
Two aircraft were conducting sightseeing flights at approximately 9,200 feet mean sea level near Mt. McKinley in Denali Park. One aircraft was a Cessna 172, registration N73813; the other was a Cessna 185, registration N1047F.
Collision Sequence
The pilot of the Cessna 172 reported flying in a generally northwest direction. He looked at Mt. McKinley, and when he returned his gaze forward, he observed the other airplane ahead and slightly higher. The collision occurred immediately thereafter.
The pilot of the Cessna 185 stated that she had just completed a radio transmission announcing her position when passengers in her aircraft spotted the other airplane. She estimated the other airplane was traveling in the opposite direction and at a slightly lower altitude.
Communication Aspects
The Alaska Supplement effective at the time of the occurrence specified that frequency 122.7 was designated for inter-aircraft communications in Denali Park, the area containing Mt. McKinley. The pilot of the Cessna 172 was not aware of this frequency. The pilot of the Cessna 185 had been using the frequency to transmit her position.
Visibility Conditions
The pilot of the Cessna 185 noted that the Cessna 172 blended with the surrounding terrain, which consisted of vertical granite walls. This made visual detection of the other aircraft difficult.