Draft:Aeroflot Flight 7502

Aeroflot Flight 7502

An Aeroflot Antonov An-24B similar to the one involved
Accident
Date	15 January 1979 (1979-01-15)
Summary	Loss of control during approach due to atmospheric icing
Site	near Minsk-1 Airport, Minsk, Byelorussian SSR
Aircraft
Aircraft type	Antonov An-24B
Operator	Dniproavia on behalf of Aeroflot
Registration	CCCP-46807
Flight origin	Tallinn Airport, Tallinn, Estonian SSR
Stopover	Minsk-1 Airport, Minsk, Byelorussian SSR
Destination	Dnipro International Airport, Dnepropetrovsk, Ukrainian SSR
Occupants	14
Passengers	9
Crew	5
Fatalities	13
Injuries	1
Survivors	1

Aeroflot Flight 7502 was a scheduled passenger flight from Tallinn, Estonian SSR to Dnepropetrovsk, Ukrainian SSR with a stop at Minsk, Byelorussian SSR. On 15 January 1979, the An-24B entered a stall during approach to Minsk-1 Airport and plummeted to a field between the villages of Medvezhino and Baranovshchina in the Frunzensky District of Minsk, leaving only 1 passenger survived of the 14 on board.

Arcraft

The plane involved was an Antonov An-24B manufactured on November 30, 1965 and registered as CCCP-46807. In 1968, ten An-24s, including this one, were converted to the An-24B. At the time of the crash, the airliner had accumulated a total of 23,844 flight hours and 17,627 landings.^[1] The plane was featured in a 1973 Soviet film “Абитуриентка”.^[2]

Crew

The An-24 was piloted by a crew from the 327th Flight Detachment and had the following composition of 5 people:^[3]

• Captain - Vasily Antonovich Goryanoy;
• First Officer - Grigory Ivanovich Lyakhovich;
• Navigator - Vladimir Nikolaevich Avramenko;
• Flight engineer - Vladimir Vladislavovich Fedorenko;
• Stewardess - Lidiya Mikhailovna Tsekalo.

Accident

At 10:14 local time (11:14 Moscow time), flight 7502 took off from Tallinn Airport, carrying 9 passengers and the 5 crew members. After gaining altitude, it reached to the cruising altitude (4,500 meters, 14,750 feet).^[4]

According to the forecast received by the crew before takeoff, overcast skies were expected in Minsk with a base of 100-200 meters (330-600 feet) and an upper limit of 1000-1500 meters (3280-4920 feet), light snow, haze, visibility of 1000-2000 meters, moderate turbulence, icing in the clouds, and a southeasterly wind (120-140°) at 9-12 m/s (17-23 knots). At 12:42 MSK, the crew contacted the Minsk Regional Center dispatcher. At 12:49, after receiving instructions, they began to descend to an altitude of 3000 meters (9,850 feet), having first activated the anti-icing system. At 12:54, the crew contacted the approach controller, who cleared them to descend first to an altitude of 2100 meters (6,900 feet), and then to 1200 meters (3,900 feet). Having reached an altitude of 1200 meters (3,900 feet) at 12:58 and being 31 kilometers (16.7 nautical miles) from the Minsk airport, the crew began communicating with the circuit controller.^[4]

At 12:59, the crew set the altimeters to the airfield pressure and, flying in clouds, began to descend to the circuit altitude of 400 meters (1,300 feet). At this time, the sky above Minsk was overcast with clouds lower than 150 meters (490 feet), haze, and light icing within the clouds. Visibility was 2,500 meters, and the wind was easterly at 6-9 m/s (12-17 knots). In other words, the weather forecast was correct, although the circuit controller did not transmit the actual weather to the crew. When the distance to the airport was 19 kilometers (10.3 nautical miles), the crew switched to contacting the landing controller.^[4]

At 13:03, the crew completed the pre-landing checklist, and then the captain, after reporting the absence of ice on the right and left wings, contacted the controller and reported: "Entered the glide path , landing gear extended, ready for landing ." The controller then cleared the landing on heading 120° and reported that they were 9 kilometers away (4,9 nautical miles). At 13:04, after the crew's request, the controller transmitted their position: distance 7 kilometers (3,8 nautical miles), 50 meters to the left, 40 meters (130 feet) below the glide path. However, the crew did not acknowledge receipt of this information and did not respond to further inquiries.^[4]

At approximately 13:05, the An-24, traveling at 130–140 km/h (70-75 knots) and descending at a vertical rate of 15 m/s, with a slight pitch angle and a right bank of 10–15°, crashed between the villages of Maloe Medvezhino and Baranovshchina into snow-covered clay pits 10–15 meters deep and covered with 2–3 meter-high bushes. The aircraft was dragged along the ground for only 14 meters before coming to a stop 5,280 meters (2,9 nautical miles) from the threshold of the runway and 200 meters to the left of its axis. The airliner was completely destroyed, with debris scattered over a distance of 30 meters, but no fire occurred^[4]

Emergency services arrived and found three seriously injured people at the crash site: two adult passengers and a young girl. Both adults later died of their injuries in hospitals. A total of 13 people died in the crash: five crew members and eight passengers.^[4]Three-year-old Vika Bendeberya was the only survivor of those on board.^[5]

Investigation

According to the investigation, "the passengers died as a result of multiple fractures of the skeleton, rupture of internal organs, traumatic shock. The crew was in their seats, the passengers were in the front rows of seats" ^[6]

While examining the debris on the leading edges of the wing, stabilizer, and vertical stabilizer , investigators discovered ice 20-40 millimeters wide and 1-2 millimeters thick. According to the commission's conclusion, the crew prematurely switched off the anti-aircraft warning system during the landing approach, although they were still in cloud cover. As a result, the wing and tail began to become coated with ice, which impaired the aircraft's longitudinal stability. 7 kilometers (3,8 nautical miles) from the runway, while the aircraft was flying at 220 km/h (118 knots) at an altitude of 300 meters (980 feet) and with the flaps extended to the landing position (38°) , the crew, after receiving information from the controller about a lateral deviation and following below the glide path, increased the engine power to 63% on the glide path . Following this, a stall occurred on the stabilizer , so the crew, acting on the flight manual, retracted the flaps to 10° and reduced the engine power to idle. Continuing to fly in the clouds, the crew did not attempt a go-around. Eighteen seconds before the crash, the An-24 reached a critical angle of attack, and its forward speed significantly decreased . It was no longer possible to recover the aircraft from this emergency situation.^[4]Assistant Prosecutor Mikola Multan believes that the main cause of the accident was the human factor^[5]

The main cause of the aviation accident was the partial loss of longitudinal stability of the aircraft in the landing configuration with flaps extended to 38°, with the stabilizer iced up due to the premature disengagement of the anti-skid system.

Contributing factors:

Flight tests to determine the longitudinal stability and controllability characteristics with ice on the stabilizer tip (dive and dive of the aircraft) were not conducted.

On the An-24 aircraft, the presence of icing on the stabilizer adversely affects the longitudinal stability characteristics.

The flight manual does not contain clear recommendations for bringing the aircraft from the pre-dive state to normal flight mode.

The flight manual does not specify the procedure for accelerating the speed when retracting the flaps and going around if the aircraft has not entered or is kept from “dive”.

Compliance with the recommendations of paragraph 4.17.5 of the Flight Manual in this case brings the aircraft to angles of attack close to critical ones.

It is impossible to simulate the signs of a "dive" on the current An-24 aircraft simulators and conduct crew training to bring the aircraft back to normal flight mode.

^[4]

References