Reports say officials believe it to be in good condition and it can be used to help determine the cause of Thursday's crash.

In choppy seas and murky conditions, the underwater search teams also discovered three large objects, believed to be sections of the fuselage.

The recorder is being handed over to a laboratory in Ottawa, where experts will try to piece together the reason for the crash.

Vic Gerden explains what can be gleaned from the recovered box

Chief Investigator Vic Gerden said the flight data recorder provides "approximately 100 parameters to work with to help us reconstruct not only the flight profile but also from many of the systems within that aircraft."

It should shed light on the condition of systems such as electrics, fuel and controls leading up to the aircraft hitting the water.

Swissair Chief Executive Jeffrey Katz walks past a memorial at the site

The search is continuing for the other black box, the cockpit voice recorder.

Investigators previously released details of the final conversations between the pilot and the control tower, which show that the plane hit the sea six minutes after losing its course.

The BBC's Tom Carver: What happened in those final six minutes?

Using a recording of the pilot's communications with the control tower and a radar track of the plane's path, investigators have pieced together a detailed picture of the airliner's final few minutes.

The first that air traffic controllers heard of the problem was 16 minutes before the crash.

The pilot announced: "Swissair 111 is declaring pan pan pan - we have smoke in the cockpit."

"Pan pan pan" is the expression used when an emergency is less acute than a mayday signal, which indicates imminent disaster. But the situation rapidly deteriorated.

Jane Hughes reports on the discovery of the black box

The pilot suggested landing at Boston, but was told Halifax was closer, so he began heading in that direction.

However, the plane was at an altitude of around 10,000 metres and needed to lose height.

Air traffic controllers also gave the pilot permission to dump at least 30 tons of fuel to land safely to help it land safely.

Jane Hughes: "The rocky shoreline is now a cemetery"

The pilot's next words on the radio were that he was declaring an emergency.

"We have to land immediately," the pilot said, the last words the controller heard from the plane.

Radar signals showed that the airliner began flying off course in a rapidly descending loop over the sea.