Missing EgyptAir plane 'did not swerve' before crash

Ehab Azmy, head of the National Air Navigation Services Company, told The Associated Press news agency on Monday that in the minutes before the plane disappeared it was flying at its normal altitude of 37,000 feet, according to the radar reading.

He says, "that fact degrades what the Greeks are saying about aircraft suddenly losing altitude before it vanished from radar".

According to Greece's defence minister Panos Kammenos, the plane swerved and dropped to 10,000 feet before it fell off radar. 

Greek civil aviation authorities say all appeared fine with the flight until air traffic controllers were to hand it over to their Egyptian counterparts. 

Meanwhile the search for the plane, which crashed with 66 aboard on Thursday, continues, with French navy ships arriving in the Mediterranean Sea on Monday. 

Furhtermore, teams searching for the black box flight recorders have been facing technical constraints.

Air crash investigation experts say the search teams scouring 17,000 square km of sea north of the Egyptian port city of Alexandria have around 30 days to listen for pings sent out once every second from beacons attached to the two black boxes until the batteries die.

At this stage of the search, they would typically use acoustic hydrophones, bringing in more advanced robots later to scan the seabed and retrieve any objects once they have been found.

French investigators say the Egyptian jet sent warnings indicating that smoke was detected on board, Aljazeera reports. The signals did not indicate what caused the smoke, and aviation experts have not ruled out deliberate sabotage or a technical fault.