MOSCOW, November 7 (RIA Novosti) - There is no indication that the crew of a Russian military Tu-142 plane that crashed late on Friday made use of emergency equipment, a highly-placed Air Force source told RIA Novosti on Saturday.

Eleven people were on board the Pacific Fleet plane that went down during a combat training flight around 21:19 local time (11:19 GMT) on Friday some 20 kilometers (12 miles) off the Tatar Strait, which separates mainland Russia from the Far East island of Sakhalin.

"There is a life-raft on board the plane that is fitted with a special device that gives out a signal in the case of an accident," the source said. "At this moment, this search-and-rescue signal has not been detected."

The source also said that the crew had not made radio contact before the aircraft went down.

According to preliminary data, the crash was caused by a technical failure.

The remains of the plane were located on Saturday morning by several ships and planes at a depth of about 44 meters (144 feet).

A search for the missing crew members is underway, although rescue officials have said there is little hope of finding anyone alive.

The source also said that if the plane's black boxes were not found within 36 hours of the crash, any information stored on them was unlikely to be retrievable.

"Unfortunately, the construction of the black boxes on this type of plane can only store information for 36 hours in salt water," the source said.