Aeroflot Flight 10 (1957). Aeroflot Flight 10 was an aviation disaster involving an Ilyushin Il-12 aircraft operated by Aeroflot, which occurred on Wednesday, 18 December 1957 30 kilometers west of Birobidzhan, resulting in the deaths of 27 people.

Aircraft 
The Il-12P with factory number 30015 and serial number 015 was manufactured by the "Banner of Labor" plant (Moscow) on 28 February 1947. The airliner received the tail number USSR-L1309 and was delivered to the Main Directorate of Civil Air Fleet under the Council of Ministers of the USSR, which initially assigned it to the Vnukovo aviation detachment of MUTA. However, in April of the same year, the aircraft was transferred to the 1st Irkutsk (134th) air transport detachment of the East Siberian Territorial Directorate of the Civil Air Fleet. The aircraft had accumulated a total of 10,436 flight hours.

Crew 
 Captain – Vasily Efimovich Lopatinikov
 First officer – Boris Andreevich Sitov
 Flight engineer – Alexander Mikhailovich Belkov
 Radio operator – Boris Boshkhoevich Mikheev
 Flight attendant – Vivia Petrovna Nikolenko

Accident 
The aircraft was scheduled to operate passenger flight 10 from Khabarovsk to Moscow, with the first intermediate stop in Magdagachi, and a crew change in Irkutsk. At 11:10, the IL-12 was positioned on the apron into the wind per the dispatcher's instructions, and passenger boarding began. The sky over the airport was covered with mid-level clouds, with a blizzard, air temperature at −13 °C, visibility at 4.5 kilometers, and, importantly, a gusty northeast wind with speeds of 20 m/s and gusts reaching 24 m/s. There were 22 passengers on board, and at 11:45, the crew requested permission to proceed to the starting position. However, the air traffic controller first asked if the rudder clamp was installed. The crew reported that all clamps were removed, and then requested permission to proceed to the takeoff without the clamp installed. The controller insisted that the clamp be installed. After some time, the crew reported they were ready to proceed to the starting position. The controller assumed the clamp was installed and gave permission to proceed. However, according to eyewitnesses, the clamp was not installed. The aircraft taxied to the starting position for five minutes, after which the crew reported completing checks per the mandatory checklist and requested takeoff clearance. When clearance was granted, at 11:58, the aircraft took off in a northeast direction (heading 52°).

After takeoff, the flight operations manager asked the crew about the takeoff conditions, but received no response. When the operations manager called again, the crew responded only with "don't interfere," but then reported: "Very bad, very bad." At this time, another IL-12, tail number L1346 (factory number 30056), was approaching for landing. The crew saw the L1309, which had not left the airport area but instead was following an approach trajectory, already in the zone of the fourth turn. Making a slow turn with almost no bank, the airliner then returned to the route trajectory. Based on the testimony of the L1346 crew, it can be concluded that after takeoff, the L1309 crew discovered a malfunction in the aircraft's control systems. Captain Lopatinikov, without reporting the incident to the operations manager, decided to return to the departure airport but then changed his mind and decided to continue the flight.

At 12:06, the crew contacted the main command and control center (GCDP) and at 12:24 finally reported a malfunction on board, stating that the rudder control had failed. The dispatcher asked what decision the crew had made, to which Captain Lopatinikov responded that they would not return to Khabarovsk due to strong winds ("it is impossible to land due to strong winds") and instead were heading to Arkhara. When the GCDP dispatcher reported this to the Khabarovsk district dispatch center, the flight operations manager there also decided that L1309 should proceed to Arkhara. The Khabarovsk center dispatcher was not monitoring flight 10 on radar. At 12:35, the crew reported passing Birobidzhan at 12:32 at an altitude of 2,100 meters. The dispatcher did not clarify the flight conditions or the nature of the malfunction on board, instead instructing the crew to switch to VHF radio communications. This was the last radio exchange with flight 10. After this, the crew no longer responded to calls. The search for the aircraft was unsuccessful, and it was declared missing.

In June 1958, the completely destroyed and burned-out airliner was found on the northwestern slope of Mount Poktoy, 30 kilometers west of Birobidzhan. The crash site was examined by an investigation commission on 15 June. Entering a descent in a spiral, the IL-12 with engines running at an 85° angle and a right bank crashed into a hillside with a 45° slope, killing all 27 people on board. According to available data, this is the largest air disaster in the Jewish Autonomous Region.

Investigation 
The commission established that earlier the same day, at Khabarovsk airport, a sudden gust of wind unexpectedly deflected the rudder of another IL-12 aircraft, tail number L1330 (factory number 30051). Upon inspection, it was found that the rudder pipe between the bell crank and the root rib was torn, and the cleats and profile stiffness near the middle attachment point of the rudder were damaged. At the time of the rudder deflection, L1330 was oriented in the same direction as L1309 would later be positioned on the apron. Based on this incident and the crew's report 26 minutes after takeoff, the commission concluded that L1309 also experienced rudder pipe failure during taxi and takeoff due to gusts of wind. In flight, the middle attachment point of the rudder to the fin failed. With probable damage to the cleats and profile stiffness at the rudder bracket suspension unit, and with the rudder axis shifting during turns, the spring compensator may have ceased functioning properly, leading to rudder overcompensation. Thus, during the flight, the rudder failed, causing a partial loss of control, and in severe turbulence, this was enough to cause the aircraft to lose control.

When the aircraft was found 7 months later, the commission discovered that the rudder pipe was twisted and destroyed, mirroring the damage seen on L1330. Thus, the commission's conclusions about rudder failure due to wind gusts were fully confirmed.

The individuals held responsible for the disaster included the deputy commander of the 198th combined aviation detachment for operations, the head of the LERM, and the flight operations manager, who knew about the L1330 rudder failure but did not issue orders to halt flights and inspect the aircraft control systems. They only instructed airport controllers to allow aircraft to taxi to the start position with rudder clamps installed, without enforcing this directive. Additionally, the air traffic controllers, despite having the necessary radar equipment, did not monitor flight 10 and failed to control the flight when it encountered difficult conditions. The aircraft commander, Captain Lopatinikov, did not follow the controller's instruction to install the clamp, resulting in rudder damage during taxiing, and the flight proceeded with a defective rudder.

References

Notes 

December 1957 events in Asia
10
Accidents and incidents involving the Ilyushin Il-12
Aviation accidents and incidents caused by weather
Aviation accidents and incidents caused by air traffic controller error
1957 disasters in the Soviet Union
1957 in Russia
Jewish Autonomous Oblast
Aviation accidents and incidents in 1957
Aviation accidents and incidents in the Soviet Union
20th-century aviation accidents and incidents in Russia