DC-7 ditching at Sitka

The DC-7 ditching at Sitka was an aviation accident (forced ditching) of a Douglas DC-7CF passenger aircraft of Northwest Orient Airlines that occurred on Monday, 22 October 1962 in Sitka Sound (Alaska); none of the 102 people on board were killed.

Accident chronology

The airliner had been chartered by the Military Air Transport Service to operate passenger flight NW293 from McChord Air Force Base (Washington) to Elmendorf-Richardson Air Force Base (Alaska). According to the flight plan, the flight was to last 5 hours 16 minutes. On board, in addition to 7 crew members, were 95 passengers: military personnel and their family members. At 16:58 the airliner took off from McChord Air Force Base and soon reached its planned altitude of 14 thousand feet (4.3 km). For two hours the flight was in clouds in which light to moderate icing was observed. The anti-icing system was switched on, which made it possible to compensate somewhat for the effect of the icing. Nevertheless, by 19:44 the crew requested and received permission from the controller to climb to an altitude of 20 thousand feet (6.1 km). The engine power setting was increased somewhat, and then increased all the way to take-off power, since there were nonetheless ice deposits on the aircraft.

When the airliner reached an altitude of 20 thousand feet, the flight engineer immediately began to reduce engine power. First the power of both outer engines (No. 1 and 4) was reduced, but as soon as they began to reduce the power of the inner left engine (No. 2), its power (BMEP) dropped first by half — from 172 to 80 units — and then further to 50, that is, to idle. Suspecting carburettor icing, the flight engineer first applied alcohol injection, then heat, and then both measures at once, but all to no avail. Emergency fuel enrichment did not help either. Simultaneously with these measures, half a minute to a minute after the malfunction occurred in the engine, the flight engineer noticed that the propeller of this engine had unexpectedly begun to increase its rotational speed above the permissible limit, overspeeding. The propeller was immediately feathered, but it continued to increase its rotational speed, which according to data at 20:04 reached 3300 min-1. Power decreased, and the aircraft's speed in turn dropped to 150–155 knots. Attempts to feather the propeller continued, while the oil level dropped very quickly and soon fell below normal. Transferring oil from the auxiliary tank resulted in the oil there also running out quickly, while the propeller continued to spin fast. The captain then immediately reduced power and began to descend, and an emergency was declared over the radio. In the situation that had arisen, the decision was immediately made to land on the water, near Baranof Island, which was about 70 miles away. Continuing its descent through the clouds, the airliner took up a new heading.

At an altitude of six thousand feet (1830 metres) the pilots were able to make out the water through the clouds, and at four thousand feet (1220 metres) the ocean surface was quite clearly visible. Having descended to an altitude of five hundred feet (150 metres), the crew maintained it and continued the flight to Baranof Island. But when they were flying over Sitka Sound (:en:Sitka Sound) near Biorka Island (:en:Biorka Island), many in the cabin, including the captain, saw that the front part of engine No. 2 was cherry-red and that metal particles were flying off it. The captain then decided to land immediately. The wave height was 6–8 feet (2–2.5 metres) when at 20:52 (12:52 local time), with flaps fully extended, at a speed of 95 knots (176 km/h), the "Douglas" ditched. The touchdown was smooth, but then two impacts followed: first a weak one and then a strong one. Because of the impacts, a life raft that had been made ready in the cabin was thrown from its place, and meal trays also fell, but no one on board was injured in the landing; only during the evacuation did a few people receive minor injuries. The aircraft was also only slightly damaged externally; only the propeller blades were bent. Lieutenant David Irons (David Irons), who was a rescue helicopter pilot, also described smoke and fire in the area of the second engine. The crew immediately began the evacuation, helping passengers into the life rafts. The captain and the first officer remained in the cockpit and threw a ten-person raft out through the right window. The evacuation took about 2.5–3 minutes, and at 20:57, five minutes after the ditching, all passengers had been evacuated into 6 (according to other data, 5) life rafts. As was later noted during the investigation, the evacuation was carried out in accordance with the established instructions, apart from some mishaps: when the straps securing the rafts were cut with special knives, several passengers mistakenly took the knives from other rafts as well, so pocket knives had to be used. The air temperature at that time was 53° F (12° C), calm, and the water temperature was 56° F (13° C).