Ice Trap: Two Air Crashes in Yugra 9 Days Apart

Two terrible air crashes occurred in Surtug (in western Siberia, Russia) 55 years ago, just 9 days apart. In both cases, Antonov An-12 planes crashed. During the landing approach, the airliners disappeared from radar. The tragedies claimed the lives of everyone on board. Today we recall the events of January 1971.

There Were Two Crews on Board the Plane

Two Antonov An-12 planes and three crews of the 75th Flight Squadron were temporarily based at Omsk Airport at that time, from where they carried out chartered cargo flights. On January 22, the task was to ferry the plane to the base airfield in Syktyvkar, where it was due for scheduled maintenance. The flight was combined with the delivery of 12 tons of household and construction goods to Surtug.

There were two crews on board the plane: the operating crew and the relief crew. These included pilots, navigators, flight engineers, radio operators, and flight attendants. Also on board were an engineer from the 75th Squadron and a cargo escort.

Around 20:00, the airliner took off from Omsk Airport. After about an hour and a half, it reached Surtug and began its descent. The air temperature was minus 9 degrees Celsius (16°F). At 21:34, the crew began the landing approach. The distance to the airport was 11 kilometers. Everything was going according to plan. At 21:36, the air traffic controller gave the command to turn. The standard response, «Roger,» was heard over the speaker. After that, the crew made no further contact. A few minutes later, the airliner crashed into the ground at a speed of about 330 km/h, completely disintegrated, and burned.

The plane was found in the forest 18 km northeast of Surtug Airport. The impact with the ground occurred at high speed. The plane was descending in a spiral with its landing gear extended and flaps not deflected. All engines were running at the moment of impact. The anti-icing system was on. All 14 people on board died.

Roman Podgorbunskikh, a resident of Surtug who has been collecting data on the January 1971 air crash, managed to find unique photographs of the graves at the central cemetery in Syktyvkar, where the members of the deceased crews are buried.

«The Crew Reported Severe Icing, and a Minute Later — Very Severe Icing»

Nine days after the first air crash, on January 31, another Antonov An-12 plane was sent to transport cargo from Tyumen to Surtug. The plane was loaded with 12 tons of fresh seafood — Pacific herring packed in boxes.

The airliner was operated by a crew consisting of a captain, a junior lieutenant, a navigator, a flight engineer, a radio operator, and a steward. The plane took off safely from Tyumen Airport, gained altitude, and headed for Surtug.

About an hour later, it reached its destination. At an altitude of 800–900 m (2,625–2,953 ft) above the city, the crew reported severe icing, and a minute later — very severe icing. The airliner continued to descend. The captain gave the order to extend the flaps, but five seconds later ordered them retracted. Another minute later, the plane crashed into the ground.

The plane crashed 16.5 km north of Surtug Airport, near one of the local lakes. The airliner was completely destroyed. Some of the wreckage, including the tail section, fell into the lake. All 7 people on board died.

Causes of the Air Crashes

Both crashes followed the same pattern. The investigation showed that the loss of control was due to icing, which was caused by insufficient effectiveness of the anti-icing system: the valves for tapping hot air from the engines were not fully open. The airliners fell into an ice trap.

To prevent similar crashes from happening again, the air bleed control system was substantially modified, including the addition of an alarm for full valve opening. Special tests were also conducted, which made it possible to clarify the aerodynamic characteristics of the Antonov An-12 during icing. This also led to changes in many civil aviation regulatory documents.

Earlier we reported on another air crash that occurred in Yugra (Khanty-Mansi Autonomous Okrug) on January 3, 1984. A heavy transport helicopter crashed to the ground, claiming 38 lives.