Egypt has deployed a robot submarine to the Mediterranean Sea in search of black boxes from the EgyptAir flight MS804.

During the investigation in the past few days investigators have found personal belongings of the passengers, body parts, aircraft chairs, and life vests, Egyptian military confirmed. But the investigators are still in search of the fuselage and  black box flight data recorders, which would exactly indicate what was the cause of the crash, reported CNN.

Egyptian President Abdel Fattah al-Sisi confirmed the deployment of the submarine on Sunday during his first public address regarding the crash. He also warned that the investigation would take some time.

The Egyptian President said, “until now all scenarios are possible. So please, it is very important that we do not talk and say there is a specific scenario. This could take a long time.”

“They have a submarine that can reach 3,000 meters (nearly 10,000 feet) under water, It moved today in the direction of the plane crash site because we are working hard to salvage the black boxes,” NBC News quoted the president.

In the meantime, Egyptian oil ministry clarified that the president was referring to a robot submarine, which is mostly used in maintaining offshore oil rigs. Fattah al-Sisi’s announcement came after an audio recording of the flight’s pilot and the air-traffic controller’s conversation was retrieved.

Apparently, the investigation has become very challenging as the flight recorder could have sunk deeper than 2,000 metres below sea level. Investigators have still hope of getting hold the black boxes as they emit signal pointing to their location. However, after four to five weeks in water, they will stop signalling as their power will run out, as per The Guardian report.

Air crash investigation experts also echoed the same possibility and said that the investigators have around 30 days time in their hand to listen some signal sent out by the black boxes of EgyptAir flight MS804. It has been expected that during the initial stage of investigation the team will use acoustic hydrophones but later more advanced robots will be used to scan the seabed.

On Saturday French aviation officials informed that the aircraft sent automatic smoke alerts from near the cockpit minutes before the crash. However, it is still unconfirmed whether the fire was due to an act of terrorism or electrical fault.