Accident An-24 in Samarkand

An-24B with tail number 46299 (serial number 77303901) was released by Antonov's factory on November 30, 1967 . In total, at the time of the crash, the airliner had a total of 19 664 flight hours and 18 323 landing ^[1] .

The aircraft performed a training flight, and its crew was piloted from the 163th flight detachment, the commander (PIC) of which was a pilot instructorA.F. Tsibizov . The crew also included two co-pilots V.V. Abramov and V. G. Casanov , who were to be retrained as commanders, navigator L. M. Kramer and the flight engineer V. M. Lyamtsev . At 06:15 (04:15 Moscow time ), the An-24 took off from Samarkand Airport . Carrying out the flight program, the crew performed eight approaches without deviations ^[1] .

In the ninth approach, a landing was worked out with one idle propeller. Cloud cover at this time was 5 points, and a crosswind was blowing, and visibility reached 40 kilometers. While practicing a landing on one engine, the crew plowed the right propeller . By the decision of the instructor, unlike the first eight, the ninth approach was not carried out according to the usual glide path , but under conditions when a restriction of 25 meters was imposed on the height of the runway end face, and was supposed to be 400 meters for the flight during landing, which the instructor warned the others about crew members ^[1] .

With 15 ° flaps and landing gear, the airliner passed the DPRM at a height of 260 meters, instead of the installed 235 meters. The decrease occurred at an increased vertical speed and at 400 meters to the BPRM the aircraft was already 15 below the glide path, when at a speed of 238 km / h the operating mode of the left engine was reduced from 22 ° to 18 ° UTRT . When 3 seconds were left before the BPRM span, the flaps were lowered to the landing position to 38 °, which at the same time led to an increase in aerodynamic drag , however, the engine operating mode was not increased, as a result of which the speed began to fall. Also, the declining plane began to gradually go left relative to the axis of the runway. Since the end of the runway needed to fly at an altitude of 25 meters and land with a flight of 400 meters, and also taking into account that the airliner was already 15 meters below the calculated glide path (2 ° 30 '), the pilots tried to reduce the speed of descent, for which they slightly pulled the helms "On yourself", thereby increasing the angle of deviation of the elevators. However, this action only increased the resistance and further reduced the flight speed, which has already decreased below the recommended RLE ^[1] .

BPRM An-24 passed at a speed of 228 km / h 25 meters to the left and 10 meters below the glide path in virtually horizontal flight. At this moment, the wind from the side changed to the headwind (azimuth of 100 °, 4 m / s, gusts up to 7 m / s). In such conditions, when only the left engine was working, and even in low mode, the thrust was already insufficient and the aircraft began to decline faster than the calculated one. When 600 meters were left to the end of the runway, the engines were briefly (for 10 seconds) switched to take-off mode. But since only the left screw worked, a turning moment arose, which began to divert the plane to the right, that the pilots tried to parry the steering wheel all the way to the left, and the resulting roll was countered by deflecting the ailerons . On a course close to the landing, the An-24 began to climb and 25 meters from the ground crossed the end of the runway, while being 5-10 meters to the right of the axis. The speed dropped to 190 km / h, as a result of which the rudder lost its effectiveness and the aircraft began to turn to the right with an angular speed of 3 ° / sec ^[1] .

Having decided to interrupt the approach , the crew removed the chassis. The aircraft, meanwhile, was increasingly deviating to the right, while slightly gaining altitude. The right roll began to grow rapidly, despite the maximum deviation of the helm to the left. After another 7 seconds, the flaps were removed, which led to the withdrawal of the airliner at supercritical angles of attack and to the start of stall ^[1] .

At 09:04 (07:04 Moscow time ) flying on the course of 190 ° An-24 with a small translational speed at an angle of 10-15 ° and with a right bank of 80 ° with a glide to the right wing crashed into the ground 690 meters from the axis of the runway and 1120 meters from its end a few meters from the shore of the irrigation canal near the fence of the motor depot. Upon impact, the plane completely collapsed and partially burned, and all 5 people on board died ^[1] .

According to the conclusions of the commission, the fact that the FAC instructor limited the flight height of the runway end and landing with a flight in flight on one engine, required after the DPRM flight to increase the operating mode of the left engine to 58 ° according to UPRT. However, the crew was late with an increase in engine power by about 10 seconds and as a result was then forced to switch the engine to take-off mode, which led to the appearance of a high turning moment. Thus, in the piloting technique, errors such as ^{[1] were made} :

• a delay of 10 seconds with an increase in the operating engine mode to prevent a decrease in altitude and flight speed (they were caused by the additional release of the flaps into the landing position);
• failure to use the entire stock of ailerons to eliminate the slip that arose due to asymmetric engine traction.

The PIC instructor himself for the first time performed the landing exercise on one engine, since the current training program for the flight crew, when admitted to instructor work, did not provide for training in this exercise, only on simulators. It was also noted that in the RLE there were no recommendations to the crew about piloting the aircraft when changing the operating engine mode ^[1] .

Conclusion : the cause of the disaster is the crew’s mistakes in piloting technology, which led to the creation of a non-landing position of the aircraft relative to the runway, loss of speed and stall on the right wing.

- ^[1]