Aeroflot Flight 3739 (1976)

Aeroflot Flight 3739

Company type	Scheduled domestic passenger flight
Industry	Aviation
Founded	9 February 1976 (date of accident)
Headquarters	Irkutsk , Soviet Union
Products	Air transport service

For the 1988 hijacking event, see Aeroflot Flight 3739 (1988).

Aeroflot Flight 3739 was a scheduled domestic service within Russia, operating between Irkutsk and Pulkovo Airport in Saint Petersburg, with an intermediate stop at Tolmachevo Airport in Novosibirsk. On 9 February 1976, the flight crashed shortly after beginning its takeoff roll from Irkutsk International Airport. The tragedy resulted in the deaths of twenty-four individuals out of the 114 passengers and crew aboard.

Aircraft and crew

The airplane involved was a Tupolev Tu-104A registered under Aeroflot. Its maiden flight occurred on 26 November 1956, and it was assigned to Irkutsk in December 1957 following a period of test operations. Initially designed to accommodate 70 passengers, the interior was later modified to increase seating capacity to 85. Before the accident, the aircraft had accumulated a total of 22,069 flight hours and completed 10,308 pressurization cycles.

The cockpit team comprised the following members:

• Ivan Nikolaevich Svistunov held the position of pilot in command
• Anatoly Fedorovich Grafenkov served as copilot
• Yuri Mikhailovich Krasnoyarsk functioned as navigator
• Vladimir Nikolaevich Dubrovsky was undergoing navigator training
• Nikolai Yefimovich Konshin operated as flight engineer
• German Vladimirovich Firstov was the radio operator
• Ariada Leonidova Shabalina acted as flight attendant-instructor

The cabin staff included three additional flight attendants.

Sequence of events

At the outset, 99 passengers boarded the aircraft in Irkutsk. Subsequently, an additional five individuals—who were not listed on the manifest—were allowed to enter the plane. Among these, four held valid tickets, while one was the adult son of the radio operator and did not possess a ticket. Of these five extra passengers, two were situated in the restrooms, two seated near the front of the cabin, and the radio operator’s son occupied a position in the cockpit. None of these additional individuals appeared in the official flight documentation. The exact locations of other standing passengers without assigned seats remain unclear. Flight 3739 commenced its takeoff roll from Irkutsk at 8:15 AM local time, heading on a course of 116°. During this phase, the aircraft began to veer toward the right; however, with significant effort, the pilots managed to bank approximately 20° to the left in an attempt to stabilize the plane. The aircraft lifted off at around 300 km/h (160 kn; 190 mph), and although the pilots briefly leveled it, it soon began tilting rightward again at an altitude near 30 metres (98 ft). The plane rapidly lost height and collided with the ground eight seconds after leaving the runway, at a steep bank angle of 70°, approximately 180 metres (590 ft; 200 yd) beyond the southeast runway end. During this accident, a Chosonminhang (now Air Koryo) Tupolev Tu-154, bearing registration P-551, sustained damage after being struck by debris from the crash.

Investigation

Initial inquiries considered that modifications made to the right wing during maintenance might have caused an aerodynamic imbalance. To verify this theory, investigators sent fragments of the right wing to the Central Aerohydrodynamic Institute, where engineers determined that the wing remained fully operational up until impact. The investigative team then replicated the flight profile using another Tupolev Tu-104 and published their results. Test flights revealed that the Tu-104 was susceptible to rolling when subjected to crosswinds. At low altitude, pilot attempts to correct this by adjusting ailerons proved insufficient; instead, a more effective response would have been to sharply reduce throttle settings. Analysis indicated that immediately after takeoff—when departing from the runway—the aircraft exceeded the flight manual’s recommended takeoff angle of 2-3°, yet remained 3-4° below stall angle; prevailing winds likely pushed the right wing into a roll. Further calculations showed that fuel distribution was uneven, with right-side tanks containing approximately 1,300–1,500 kilograms (2,900–3,300 lb) more fuel than those on the left, contributing to the rolling tendency.

A Chosonminhang (now Air Koryo) Tupolev Tu-154, similar to the aircraft hit by debris

Causes

The USSR Ministry of Aviation Industry’s investigative commission identified these as primary factors behind the crash:

1. Unequal refueling resulted in roughly 1300–1500 kilograms more fuel in right-side tanks compared to left-side tanks, causing a rightward roll;
2. The pilot’s inadequate reaction to emergency conditions, notably disregarding automatic angle-of-attack and vertical overload warnings for eight seconds before taking corrective action;
3. An increasing right bank immediately after runway departure that could not be countered using ailerons alone.

External links

• ASN