Russian authorities launched an operation Tuesday to recover the flight recorders from an Armenian passenger plane that crashed in the Black Sea, sending a robotic device with a hydraulic arm to the sea floor in an attempt to bring up the "black boxes."

Authorities hope the recorders will help determine the cause of the May 3 crash of the Armavia Airbus A-320, which plunged into the sea in heavy rain and poor visibility as it approached the airport on a flight from the Armenian capital, Yerevan, to the Russian resort city of Sochi, killing all 113 people on board.

An official involved in the operation said the recovery device was lowered from a ship and reached the sea floor, where the recorders were believed to by lying about 15 feet apart at a depth of just under 1,640 feet, the ITAR-Tass news agency reported.

The RT-1000 apparatus has been used by geologists to lift natural objects weighing up to 88 pounds from the sea floor, but has not been used at such depths, ITAR-Tass quoted a Transport Ministry official, Alexander Davydenko, as saying.

He said authorities believe the device can lift fragments of the plane weighing up to 26 pounds and the flight recorders, which weigh 15 pounds, the report said. The operation to pinpoint the boxes and lift them to the surface could take three days, officials said.

Russian prosecutors dismissed the possibility of terrorism, and officials pointed to the rough weather or pilot error as the likely cause. But officials with Armavia have suggested that air traffic controllers should at least share the blame.

The plane had covered most of its route from Yerevan to Sochi when it turned back after air controllers in Sochi said the weather was too rough for landing, but it headed for Sochi again after air traffic controllers said the weather had improved.

Mikhail Bagdasarov, the owner of Armavia, said days after the crash that a controller had "made a mistake that worsened the situation" by ordering the crew to make another run when it came too close, but that other factors may also have been involved. The plane was turning back when it hit the water.

On Tuesday, Bagdasarov said that "the weather was bad, of course, but not so bad that an A-320 could not land."

Russia's air force chief, however, was adamant that weather caused the crash and said the plane should not have turned back toward Sochi after the decision was made to return to Yerevan — a decision he seemed to blame on the plane's crew.

"It is obvious that the pilots misread the [weather] conditions," RIA-Novosti quoted Gen. Vladimir Mikhailov as saying.

"The weather is to blame for everything," ITAR-Tass quoted him as saying. "We'll get these recorders, decode them, and this will only be confirmed."