Aeroflot Flight H-75

The Aeroflot Flight H-75 was an aviation accident involving an Antonov An-24B aircraft operated by the Kyiv United Aviation Squadron (Aeroflot), which occurred on Sunday, January 6, 1974, near Mukachevo, resulting in the deaths of all 24 people on board.

Aeroflot Flight 75

Antonov An-24B operated by Aeroflot
Accident
Date	6 January 1974 (1974-01-06)
Summary	Icing
Site	Soviet Union near Mukachevo, Zakarpattia Oblast (USSR, USSR)
Aircraft
Aircraft type	Antonov An-24B
Operator	Soviet Union Aeroflot (Ukrainian Civil Aviation Directorate, Kyiv Aviation Enterprise)
Registration	CCCP-46357
Flight origin	Soviet Union Zhulyany, Kyiv
Stopover	Soviet Union Ivano-Frankivsk
Last stopover	Soviet Union Mukachevo
Destination	Soviet Union Mukachevo
Occupants	24
Passengers	18
Crew	6
Fatalities	24

Aircraft

The An-24B with registration CCCP-46357 (serial number 07305807, manufacturing number 058-07) was manufactured by the Kyiv Aviation Plant on January 23, 1970. The airliner was delivered to the Ministry of Civil Aviation of the USSR, which transferred it to the Kyiv United Aviation Squadron (86th Flight Squadron) of the Ukrainian Civil Aviation Directorate on February 2. The aircraft had accumulated a total of 9,280 flight hours and 8,083 takeoff-landing cycles..

Crew

• Captain — Komissarov Pavel Dmitrievich
• First Officer — Yevnitsky Gennady Vasilievich
• Navigator — Grysyuk Alexander Petrovich
• Flight Engineer — Borovkov Viktor Pavlovich
• Flight Attendant — Slepukhina Zinaida N.
• Escorting Police Officer — Lazaretz Oleg Vasilievich

Accident

The aircraft was scheduled to operate domestic flight N-75 from Kyiv to Ivano-Frankivsk to Uzhhorod. However, on that day, the Uzhhorod Airport was unable to receive aircraft due to its runway being in unsatisfactory technical condition, leading planes to land at the nearby military Mukachevo Airfield. Mukachevo was also closed due to poor weather conditions, causing flight N-75 to be delayed at Ivano-Frankivsk Airport..

After the weather improved, the forecast along the route included numerous stratocumulus clouds with a base of 100–150 meters and a top of 500–1000 meters, visibility of 1000–1500 meters, mist, and icing in clouds. At 14:51, flight N-75 departed from Ivano-Frankivsk and after reaching altitude at 14:57, it leveled off at an altitude of 3,000 meters. However, at 15:04, the controller in Lviv instructed the crew to descend to an altitude of 2,400 meters due to air traffic conditions. At 15:09, the crew reported passing the waypoint Vysoke at 2,400 meters and subsequently switched communication to the Mukachevo airfield controller, continuing the flight at approximately 400 km/h..

At around 15:14, four minutes before reaching the waypoint Serednie, the crew began descending at a vertical speed of 7.5 m/s to an altitude of 2,100 meters, then reduced speed to 300 km/h. The crew continued descending to 400 meters, likely extending the landing gear in advance. During the descent, the An-24 entered cloud cover, emerging six minutes later. The sky over Mukachevo was covered with stratocumulus clouds at 120 meters, the air temperature was −1°C, there was calm, mist, and visibility was 1,100 meters..

The controller indicated that the landing would be on a magnetic course of 22°. Following this, as per his instruction, the crew turned to the opposite landing course and began executing the third turn 11 kilometers from the runway. As the aircraft proceeded to the fourth turn at 310 km/h, the pilots extended the flaps to the landing position, after which the speed dropped by 45 km/h over 50 seconds. As a result, the engine power was increased at 260 km/h. When the aircraft completed the fourth turn at around 15:24 and aligned with the landing course, the engine power was reduced, and the flaps were fully extended. Sixteen seconds later, the speed decreased to 240 km/h, prompting the crew to increase engine power again. The speed initially dropped to 220 km/h, then increased to 230 km/h, leading to another slight reduction in engine power..

The aircraft was 200 meters above the ground when the pilots, attempting to level the aircraft, first pushed the elevator down. The aircraft pitched steeply downward, prompting the elevator to be pulled up to raise the nose. However, the airliner rolled to the left up to 30°. The pilots tried to recover, but at 15:25, the inverted An-24, descending at a 70° angle, severed wires on wooden poles 100 meters past the outer marker, then crashed into a dirt road on a field, completely destroyed, and burned. All 24 people on board perished..

Causes

After examining the flight data and inspecting the aircraft wreckage, the technical commission concluded that the anti-icing system had not been activated.

The cause of the accident was a loss of longitudinal control on the final approach due to a possible insufficient margin of attack angles of the horizontal stabilizer in the landing configuration with flaps extended to 38° in light icing conditions.
Contributing factors:

1. Lack of warning information to the crew about the stabilizer reaching angles close to critical.
2. Non-activation or premature deactivation of the wing and stabilizer anti-icing system in the presence of light icing (2-3 mm).
3. Absence of reliable onboard information about the presence of aircraft icing.

In the final report, representatives of the Ministry of Aircraft Industry recorded the following statement:

The loss of longitudinal stability (nose dive) when the control wheel was pushed forward before passing the outer marker, which can be explained by flow separation from the lower surface of the stabilizer in the presence of ice on the leading edge of the stabilizer with flaps extended to 38° and increased engine power mode of 50kg/cm². Icing occurred due to the crew not activating the wing and empennage anti-icing system, exacerbated by the absence of a message from the airport control service to the crew about forecasted icing conditions.

External Links

• Accident description at the Aviation Safety Network
• "Crash of an Antonov AN-24 in Mukachevo: 24 killed". B3A Aircraft Accidents Archives. Archived from the original on 2015-04-02. Retrieved 2015-03-31.