Tupolev ANT-6 (TB-3 & G-2) accident at Mt Hatis, Armenia, 10 Dec 1942 (CCCP-L2009)

Accident narrative

On December 9, the airplane departed Ashgabat on a flight to Yerevan with intermediate stops in Krasnovodsk, Baku and Tbilisi. The last sector to Yerevan was postponed to December 10 and the crew passed the overnight in Tbilisi. The airplane took off at 1140LT and weather conditions were considered as good. Approaching Lake Sevan at an altitude of 3,700 metres, weather conditions deteriorated with clouds and snow falls. The pilot attempted to return to Tbilisi but this was too late and as the airplane was flying over a mountainous area, the pilot finally decided to continue to Yerevan. Descending to the altitude of 2,500 metres in clouds, the airplane impacted the north slope of Mt Hatis (2,528 metres high) located 22 km northeast of Yerevan. The airplane was damaged beyond repair and all five crew members were rescued, among them four were injured.

Probable cause (official findings): The main reason for the accident was the failure to report to Tbilisi a snowstorm coming from Yerevan, which had started at 1215LT over the Sevan area. According to available weather information, confirmed by forecasts, the pilot, after crossing a pass at an altitude of 3,700 metres, descended below fragmented clouds to an altitude of 2,700 metres, according to the altimeter. After flying for several minutes below the clouds, he encountered snowfall and was unable to return as the clouds had become compact. The following factors were identified: - The presence of a storm in the Sevan area and the associated low pressure area distorted the actual altitude readings. - A spontaneous and unstudied short-term weather change. - The telegraph operators at Sevan-Yerevan showed criminal negligence in transmitting the warning message. As a result, the message, received at 1220LT as scheduled, was transmitted to Yerevan at 1237LT, then to Tbilisi at 1347LT (1 hour and 10 minutes after receipt) and never reached Tbilisi. The absence of this information deprived the pilot of the opportunity to warn him of the storm in the Sevan region before approaching the pass.