Russian Flight Recorders Offer No Clues on Crashes

MOSCOW —  A top Russian official said Thursday that the flight data recorders from two jetliners provided no clues about why they crashed minutes apart Tuesday, but he acknowledged that terrorism was probably the cause.

A day after officials stressed that there were many possibilities besides terrorism, Vladimir Yakovlev, the presidential envoy to southern Russia, told the Itar-Tass news agency that the main theory “all the same remains terrorism.”

He said both recorders had shut off abruptly without any indication of trouble, a sign that U.S. aviation experts said was strong evidence of explosions.

“Practically speaking, they switched themselves off immediately. And so we failed to get any information,” Yakovlev told ORT television.

Despite Yakovlev’s statement about terrorism, the government was still investigating all possibilities, including mechanical failure, bad fuel and human error. Officials said no evidence had been found pointing to terrorism, and no one has claimed responsibility.

Relatives went to the crash sites to identify victims. A total of 89 people were killed.

Thursday was a national day of mourning. Russia’s flag flew at half-staff, and TV stations canceled entertainment programs.

Transportation Minister Igor Y. Levitin confirmed Sibir Airlines’ report that the crew of its Tu-154 activated an emergency signal shortly before their plane disappeared from radar. Visiting the crash site, however, he said that details were slim because “no verbal confirmation from the crew was received” on what the problem was.

The airline said the fact that wreckage was scattered so widely indicated that there might have been a midair explosion.

Officials previously said there was no indication of trouble from the Volga-Aviaexpress Tu-134 airliner that crashed, although people on the ground reported hearing a series of explosions.

Suspicions of terrorism came after officials warned of separatist attacks before an election Sunday in Chechnya to replace the war-torn region’s assassinated pro-Kremlin president.