Two Tupolevs were parked next to each other, check-in was at same counter and they took off within minutes

Sabotage is the most likely cause of two Russian airliner crashes that happened within minutes of each other on 24 August, according to evidence uncovered late last week. Traces of hexogen, an explosive widely manufactured in Russia, have been found in the wreckage of one of the aircraft - a Sibir Airlines Tupolev Tu-154B-2 and officials have confirmed that the flight data recorders on both aircraft stopped abruptly before the aircraft disappeared from radar.

Shortly before the Tu-154B-2 crashed the pilot had time to set the international hijack code on the transponder, air traffic control has confirmed. At the crash site its tail section was found 1km (0.6 miles) from the centre fuselage. Meanwhile, wreckage from the second aircraft, a Volga-AviaExpress Tu-134A-3 that disappeared from radar 3min later, was spread across an area about 10km2 (3.8 miles2), according to the search and rescue agencies who found it more than 24h later.

Both aircraft were flying scheduled domestic passenger services from Moscow Domodedovo airport on 24 August, with a total of 90 people on board. Radar returns from the two airliners disappeared almost simultaneously, the Sochi-bound Sibir Tu-154B-2 at 22:56 local time, the Volgograd-bound Volga-AviaExpress Tu-134A-3 at 22:59.

The crashes took place about 500km from each other. Minister of transport Igor Levitin is heading the commission investigating the crashes. "Special groups" have been established by the ministries of interior, defence and emergencies to study the events.

The Tu-154 was operating flight S7 1047 to Sochi on the Black Sea coast, taking off from Domodedovo at 21:35 - 10min later than scheduled - carrying 38 passengers and eight crew, says Sibir. The wreckage was found about 08:30 the next day 9km from the village of Glubokii about 140km north of Rostov-upon-Don.

Sibir claims that soon after the crash, Russia's air traffic control main centre sent out a message ordering airports to adopt a higher degree of readiness and confirming that one of the aircraft signalled a "hijacked" code before the crash.

Check-in for both flights was at the same counter and the aircraft were parked next to each other. The Tu-154, registration RA-85556, entered service in 1982 and had flown 30,751h but was lifed for 37,000. The aircraft's last full overhaul was in August 1993. A B-check was performed on 10 August.

Volga-AviaExpress flight ZH 1303 to Volgograd was a Tu-134A-3 (RA-65080) in KolAvia colours, built in 1977, carrying 35 passengers. It took off at 22:16, about 40min after the Tu-154.

VLADIMIR KARNOZOV / MOSCOW

Source: Flight International