Moscow-Domodedovo Approach Incident: Pitot Tube Icing and Emergency Diversion (CCCP-85327)

Flight Overview and Weather Conditions A commercial flight departed Chelyabinsk for Moscow under generally favorable weather conditions. As the crew began the descent toward Moscow-Domodedovo, weather deteriorated due to a cold front passing over the city. At an altitude of 3,600 meters, the aircraft entered an area of heavy rain and icing. ## Instrument Failure and Emergency Descent The Pitot tubes became obstructed by ice, which altered the settings of certain instruments. The airspeed indicator dropped to zero, leading the crew to believe the aircraft was approaching stall conditions. In response, the crew initiated an emergency descent with a rate of 100 meters per second and a speed of 813 km/h. The aircraft experienced positive acceleration of 3.2 g, resulting in structural damage. ## Diversion and Outcome The crew diverted to Moscow-Sheremetyevo Airport, where an emergency landing was completed. All 185 occupants evacuated safely. The aircraft was subsequently declared damaged beyond repair due to irreparable damage to the main fuselage structure. ## Probable Cause The official investigation determined that the crew failed to prepare the aircraft properly at Chelyabinsk Airport and did not follow the pre-takeoff checklist. As a result, the Pitot heating system was not activated, allowing the Pitot tubes to become obstructed by ice during descent.