Aeroflot Flight 1912

Template:Infobox Aircraft accident

Aeroflot Flight 1912 was a scheduled domestic service operated by Aeroflot on the route from Odesa International Airport through Kiev (Kyiv), Chelyabinsk, Novosibirsk, Irkutsk, and Khabarovsk, destined for Vladivostok. On 25 July 1971, the flight experienced a hard landing at Irkutsk Airport, touching down approximately 150 metres (490 ft) short of the runway threshold. This resulted in the left wing breaking and the aircraft catching fire. Of the 126 individuals on board, only 29 survived.

Aircraft

The airplane involved was a Tupolev Tu-104B, bearing registration CCCP-42405, assigned to the West Siberia Civil Aviation Directorate under Aeroflot. At the time of the crash, this aircraft had accumulated a total of 19,489 flight hours along with 9,929 pressurization cycles.

Crew

The crew assumed control of the flight at Novosibirsk. There were eight crew members on board, including five personnel assigned to cockpit operations.

The cockpit team included:

• A. V. Ovchinnikov as the pilot in command
• A. A. Pinchuk acting as co-pilot
• G.P. Guslyakov fulfilling duties as flight engineer
• I. V. Shchepkin serving as navigator
• V. I. Bolotin working as radio operator

Cabin services were provided by flight attendants G. K. Eselevich, L. B. Shokina, and A. N. Sorokin.

Synopsis

The segment of the journey from Odessa through Kyiv, Chelyabinsk, and Novosibirsk was operated by a separate aircraft and crew; during the layover at Tolmachevo Airport in Novosibirsk, passengers and their baggage transferred to CCCP-42405. At 04:34 local time (01:34 Moscow time), this new crew and aircraft departed Novosibirsk en route to Irkutsk, maintaining a cruising altitude of 10,000 metres (33,000 ft) after takeoff.

Upon arrival in Irkutsk, the sky was entirely overcast with stratus clouds, presenting a cloud ceiling at 150 metres (490 ft). The weather featured gentle north-easterly winds and visibility measured approximately 1,500 metres (4,900 ft). The flight crew received instructions to continue on the final approach along a bearing of 116°. At 08:10 local time (03:10 Moscow time), air traffic control authorized flight 1912 to commence its descent. By 08:29:35, the crew was given clearance to descend to an altitude of 400 metres (1,300 ft) along with landing directions. The pilots acknowledged receipt of the information and confirmed initiating the approach using the ILS. Subsequently, the controller relayed current weather conditions to the flight. At 08:31:52, the aircraft was approximately 17 kilometres (11 mi; 9.2 nmi) from the runway while on approach. Initially, the plane maintained its intended course; however, when it reached about eight kilometres (5.0 mi; 4.3 nmi) from touchdown, air traffic control alerted the crew that they were veering left. At 08:33:45 local time, with the aircraft just seven kilometres (4.3 mi; 3.8 nmi) away from the runway, a warning was issued regarding their proximity to missing the glide slope. In response, the pilots indicated that the landing gear had been deployed and they were prepared for landing.

At 08:33:58, permission to land was granted and confirmed by the crew. By 08:34:18, they reported being near the non-directional beacon. The controller again cautioned about a slight leftward deviation. Although the recommended instrument approach speed for the Tu-104 is 300 km/h (160 kn; 190 mph), it is probable that speed instruments overestimated velocity, leading the crew to attempt slowing down unnecessarily. In reality, actual speed hovered around 270–275 km/h (146–148 kn; 168–171 mph), which induced a left bank and caused a lateral displacement of approximately 30 metres (98 ft). At 08:34:47, the aircraft passed over the non-directional beacon at an altitude near 85 metres (279 ft).

Flying roughly 25–30 km/h (13–16 kn; 16–19 mph) below recommended speed brought the aircraft into a critical angle of attack. At 08:35:00, descending vertically at an estimated rate of 8–10 m/s (26–33 ft/s), the Tu-104's right landing gear struck the runway surface 154 metres (505 ft) from its threshold; milliseconds later, both left and nose landing gear made contact as well. Shortly after touchdown, structural failure occurred in the left wing; fuel leakage from ruptured tanks ignited upon exposure. The plane skidded along the runway causing fragmentation of the fuselage over an area spanning roughly 500 metres (1,600 ft; 550 yd). The accident resulted in 97 fatalities including the captain, co-pilot, flight engineer, one flight attendant, along with 73 adult passengers and 20 children. Among these casualties, 36 deaths were attributed to carbon monoxide poisoning.

Causes

The aircraft approached the runway at a speed significantly below the advised threshold. It is probable that faulty instrument readings led the crew to reduce velocity prematurely, resulting in a hard touchdown. Inspection of the airspeed gauges confirmed their operational status; however, flight trials revealed that fluctuations in cabin pressure influenced the pressure within the full-pressure line of the co-pilot's and navigator’s speed indicators. This caused an overestimation of speed by approximately 17 to 80 km/h (9.2 to 43.2 kn; 11 to 50 mph). During simulated flights aimed at identifying the source of the incorrect readings, cabin depressurization occurred roughly three minutes after deactivating pressurization systems. The likelihood of such depressurization during descent was estimated at 0.000001%.

The official inquiry identified three main factors contributing to the accident: Template:QuoteTemplate:QuoteTemplate:Quote

See also

• Aeroflot Flight 964, another Tupolev Tu-104 that crashed during approach due to a similar artificial horizon malfunction.
• Aeroflot Flight 2415, a Tu-104 accident caused by instrument failure shortly after takeoff.
• Aeroflot Flight 3932, a further Tupolev Tu-104 crash shortly after departure involving comparable artificial horizon issues.