1993 aviation incident in Armenia
Kuban Airlines Flight 5719 was a flight during which an aviation accident occurred involving an Antonov An-26b aircraft of the Russian airline Kuban Airlines, on Sunday, December 26, 1993 during landing at Shirak International Airport in Gyumri (Armenia), causing the deaths of 35 people. It was the largest aviation disaster in Armenia since 1991.
Aircraft.
The Antonov An-26B with the initial registration number CCCP-26141 (serial number — 12903, manufacturing number — 129–03) was manufactured by the Antonov plant in 1983. The liner was delivered to the Ministry of Civil Aviation of the USSR, which transferred it on April 14 to the North Caucasus Civil Aviation Directorate. On December 15 of the same year, the 26141 aircraft was temporarily assigned to the Far Eastern Directorate, but returned to the North Caucasus on June 16, 1984. In 1993, the aircraft with the new registration number RA-26141 began to be operated by the new airline Kuban Airlines.
Circumstances.
The aircraft was performing commercial flight GW-5719 from Krasnodar to Gyumri, transporting two VAZ-2121 "Niva" vehicles and luggage. The total weight of the cargo was 2900 kg, with six attendants. The aircraft crew consisted of five people, with Commander Aristarkhov. The total calculated weight of the aircraft was 23988 kg, close to the maximum limit of 24000 kg. According to the weather forecast received by the crew, continuous cloud cover with a base of 90 meters, fog with vertical visibility up to 90 meters, and sometimes thickening fog reducing visibility to 200 meters and vertical visibility to 60 meters were expected in Gyumri. Based on this data, Commander Aristarkhov decided to take off for Gyumri. At 17:30 MSK, the aircraft was ready for the flight, and at 17:44, the crew contacted the taxiing controller to request engine start-up. However, the taxiing controller repeatedly prohibited engine start-up, stating that it was the instruction of the flight chief. It turned out that this delay was due to a unique reason — the controller wanted to board passengers without tickets, passing customs control. While the aircraft was on the aerodrome, the controllers, with the security personnel, first boarded 4 passengers with luggage, then 8 more. At 18:27, the crew finally received permission to start the engines, and at 18:32, began taxiing to the pre-departure area. During taxiing, 13 more passengers boarded. The calculated loading weight then reached 5628 kg, bringing the takeoff weight to 26246 kg, an overload of 2246 kg. The balance, however, was within the permissible rear limit. At 18:46, the Ан-26 with 5 crew members and 31 passengers on board took off from Pashkovsky Airport (Krasnodar).
It is noted that at the time of the aircraft's takeoff, the weather in Gyumri was already poor: the airport was enveloped in fog, and visibility dropped to 700 meters. However, an hour and a half earlier and until 19:30, the controllers in Gyumri and Krasnodar stopped exchanging weather information. Although during the flight, the crew of 26141 was warned twice by the crews of planes returning from Gyumri that the fog was dense with visibility reduced to 300 meters. Moreover, when the aircraft was near Stavropol, the controller of the North Caucasus Air Traffic Management Center (СКЦ АУВД) contacted the crew to know if they intended to continue their flight to Gyumri, receiving an affirmative response. When the aircraft approached the limit of the Gyumri control center, the crew established a connection with the airport controller and reported its entry into the zone at an altitude of 5700 meters. The controller reported a horizontal visibility of 600 meters at the airport and asked the crew for their decision. The airport's meteorological minimum for Ан-26 aircraft performing an approach by trajectory guidance system was 60 on 800 meters, so the crew had to head to an alternate airport or wait for an improvement in weather conditions. The commander declared his intention to land and requested a descent to 4500 meters. At this altitude, the controller informed that the visibility at the airport had fallen to 400 meters, the crew responded "Understood" but continued to descend to 3600 meters, the transition altitude. At this altitude, the crew contacted the approach controller, indicating a descent for an approach based on radio beacons. The approach controller reported a visibility of 400 meters at the airport and a pressure of 642 mm Hg, authorizing the descent despite knowing the meteorological minimum of 200 on 2500 meters for this approach. The crew knew that the weather conditions were below the minimum but started the descent anyway. They set the altimeters to 640 mm Hg, slightly below the reported pressure, falsifying the readings by 26 meters. However, this did not affect the flight as the crew used the radio altimeter.
Disaster.
Knowing that the weather conditions at the airport were below the minimum required for Ан-26 aircraft, Commander Aristarkhov, however, wanted (needed) to land in Gyumri, which made him nervous and led to mistakes. In particular, the auxiliary power unit was not activated, as required by the operating manual in case of approach at a mountain airport for an aircraft weighing 20100 kg or more. During the third and fourth turns, the crew deployed the lift-enhancing devices and the landing gear hastily. On the descent path, the flight speed varied from 260 to 216 km/h instead of 230 km/h, engine power varied from 13 to 47° on the throttle position indicators, the course varied from 10 to 20°, with right and left inclinations of 8 to 10°, the movements of the depth controls created vertical loads of 0.85 to 1.3 units, the vertical speed varied from 2 to 12 m/s, and the actions on the ailerons were very marked. At 20:54:15, the controller announced that the visibility at the airport had dropped to 200 meters, the aircraft passed the outer marker (DPRM). After passing the DPRM, the crew stabilized the speed at 230 km/h, but the vertical speed was 4 m/s instead of 3 m/s, making the aircraft descend below the normal path and the outer marker was crossed at an altitude of 40–50 meters, 20 meters below the standard. The pilots seemed to be looking for visual references, causing inclinations of 8-10° to the right and left, and course variations of 10 to 25°. Four to five seconds after passing the outer marker, the aircraft was at an altitude of 10–20 meters, when the pilots pulled the stick, raising the nose of the aircraft, creating a load of 1.2 units and reducing the descent speed to 1 m/s. The engine power was reduced from 30 to 22° on the throttle, slowing down the decrease in flight speed. Ten seconds later, the aircraft passed the runway threshold, the speed decreasing to 216 km/h. On the distance between the outer marker and the runway threshold, the aircraft was inclined to the right by 12°, but at the moment of crossing the threshold, the inclination was reduced to 1-2°.
In horizontal flight, the 26141 aircraft crossed the runway threshold at an altitude of 15–25 meters. The speed continued to decrease, the engine power was increased to 48° on the throttle, slowing down the rate of speed decrease. During the flight over the runway, the angle of attack and pitch angle increased to 6-8°, making the flight path horizontal, which shifted the angle of vision higher, making it difficult to perceive close visual references. With visibility on the runway at 200 meters, the runway became difficult to discern. At a speed of 190 km/h, the aircraft was 1000 meters from the runway threshold when the controller ordered: "Climb to eight hundred meters". The commander decided on a go-around, pulling the stick sharply to pitch the aircraft up and setting the engines to takeoff power. At 20:56:28, he informed the controller: "I am climbing to eight hundred meters". The Ан-26, with the flaps in the landing position (deployment angle — 38°), started to climb with a vertical speed of 2–3 m/s, the crew retracted the landing gear. But due to the high weight of the aircraft, the engine thrust was insufficient, the speed started to decrease. The aircraft climbed for about 30 seconds to 95 meters, the speed dropped to 165 km/h, entering a stall, the aircraft tilted to the right and descended, at 20:57:01 with a tilt of 60°, a vertical speed of about 20 m/s and a flight speed of 150 km/h, it crashed to the ground to the left of the runway at 2990 meters from the threshold. The Ан-26 was completely destroyed and burned. One passenger was seriously injured but survived. The 35 other people on board (30 passengers and 5 crew members) perished. As of 2015, this aviation disaster is the second deadliest in Armenia, and the largest in the country since 1991. It is noted that the largest aviation disaster in Armenia is the 1988 Soviet Air Force Il-76 crash near Leniankan (name of Gyumri at the time) in 1988, killing 77 victims with only one survivor.
Causes.
According to the investigation commission, the cause of the disaster was a loss of speed by the crew during the go-around with an overloaded aircraft, leading to a critical angle of attack, a loss of speed, and a stall leading to ground impact. The disaster resulted from the following factors:
It is likely that the commander decided to land in Gyumri because 25 passengers without tickets were on board, resulting from poor management by the security and control services at Krasnodar.
Notes and references.
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