Page:CAB Accident Report, Alaska Airlines Flight 779.pdf/3

 30- to 40-foot below-glidepath condition until it was over the approach lights, which begin 1,460 feet before the threshold of the runway. He stated that at no time did he consider the flight to be in danger, and that the 30- to 40-foot below-glidepath condition was still well above the minimum safe altitude for the approach. He said that when the flight was over the approach lights, it started to descend rapidly and he assumed the captain had taken over visually for his landing, intending to "grease it on" at the end of the runway. He therefore did not advise the pilot of his position relative to the glidepath at that point. The controller said that he continued to advise the flight that it was below glidepath (though not stating how far below, or that the safety limits were being exceeded). He stated that he last saw the aircraft on radar at the end of the runway, and also that he knew it had crashed because he did not see the aircraft target move down the runway as he usually is able to do by reference to his radar scope. He also stated that the flight's transmissions indicated to him that the pilot understood all instructions and was familiar with the GCA approach to Shemya's runway 10.

The crash took place at 0211. At 0212, in response to notification of the incident, the U. S. Weather Bureau observer made the following weather observation: "Indefinite 200-foot variable ceiling; visibility 3/4 mile variable, fog; temperature 45°; dewpoint 45°, wind south-southeast 8 knots; altimeter setting 29.84; ceiling 100 feet variable to 300 feet, visibility 1/2 mile variable to one mile."

Published GCA approach weather minimums at Shemya for Alaska Airlines flights are ceiling 200 feet and visibility one-half mile. The ceiling heights are reported in feet above the runway, and the reported visibility is an average visibility using a visibility reference chart which depicts objects at known distances and directions from the Weather Bureau Office.

The wind at slightly more than 500 feet above the runway was south at 20 knots, while the surface wind was southeast at 8 knots. The freezing level was at 12,000 m.s.l. Official sunset, July 20, 1961, was at 2137, and civil twilight ended at 2223. Civil twilight began the morning of July 21, at 0443, and official sunrise was 0527. The moon had set at 0046 on July 21.

Runway 10 is macadam and is 9,990 feet in length, 200 feet wide, and its elevation is 95 feet m.s.l. There are six pairs of red approach lights extending 1,460 feet outward from the threshold. They are spaced at 200-foot intervals and are 200 feet apart in width. From the edge of the threshold pavement to a point 186 feet in the direction of an approaching aircraft, the ground slopes downward gradually at an angle of about one degree. Then the ground drops suddenly at an angle of approximately 30 degrees to a valley floor 50 to 60 feet below the level of the runway.

The six pairs of approach lights are mounted on poles of different heights to accommodate the variance in terrain height, but the lights themselves are practically on a level with the runway. A single strobe light is located on the ground, aligned with the runway centerline approximately 152 feet short of the runway threshold. There are two pairs of green threshold lights, each pair mounted side by side (crosswise to the runway), one pair at each corner of the runway. Thereafter, at 200-foot intervals, single runway lights extend the full length of the runway along both sides. All lights (except the strobe light) utilize 200-watt bulbs.