Time for investigators to recover the black boxes of crashed jet flight Air France 447 is running out as they will continue to emit signals for approximately another six days.

The two recorders are essential to help determine what happened to the crashed jet that plunged into the ocean killing all 228 people on board.

The black boxes' locator beacons, known as pingers, emit signals for 30 days after the crash. After this time has passed, it could become impossible to locate the black box flight recorders and discover what happened to the Airbus A330 which crashed approximately four hours after taking off from Rio en route for Paris.

Searchers have been combing an area with a radius of 50 miles in the hope of detecting signals from the boxes that can be heard only up to about two miles.

The Airbus A330 plane fell into the Atlantic on May 31after running into thunderstorms en route from Rio de Janeiro to Paris.