Q&A: key questions about missing EgyptAir flight MS804

Do we know what happened to it?

The aircraft was about 175 miles (280km) from the Egyptian coast when it disappeared, travelling at an altitude of 11,000 metres (37,000ft).

The Greek defence minister said that after entering Egyptian airspace the plane fell 22,000 feet and swerved sharply before it disappeared from radar screens. French president François Hollande confirmed that the plane had crashed, and said “no theory could be ruled out”.

Reuters cited a Greek defence ministry source who said authorities were investigating reports from the captain of a merchant ship of “a flame in the sky” around 130 nautical miles south of the Greek island of Karpathos.

The plane had left Paris at 11.09pm on Wednesday night (21.09 GMT/07.09am Thursday AEST) and disappeared at 2.30am, about 45 minutes before it was scheduled to land.

Egyptian authorities initially reported that a signal had been received two hours after the plane dropped off radar, but Egypt’s minister of civil aviation, Sherif Fathy, later said that statement had been based on a mistake by an official.

Egypt says military search and rescue teams have been dispatched to the site where the plane vanished from radars. Greece also has sent one C-130 Hercules and one early warning aircraft. One Greek frigate is also in the area and helicopters are on standby on Karpathos for potential rescue or recovery operations.

Two large pieces of plastic, possibly debris from a plane crash, have been found south-east of Crete, and ships have been sent to investigate.

Who was on board?

The plane was carrying 56 passengers and 10 crew: two cockpit crew, five cabin crew and three security personnel. The airline said two babies and one child were on board.

The nationalities of the passengers were as follows: 30 Egyptians, 15 French citizens, two Iraqis and one person each from Britain, Belgium, Sudan, Chad, Canada, Kuwait, Saudi Arabia, Portugal and Algeria.

What kind of aircraft was it?

An Airbus A320 – considered a safe and reliable plane. Nonetheless the model has been involved in safety incidents in the recent past, including the Germanwings tragedy in March 2015 that claimed 150 lives. It was also the aircraft Chesley Sullenberger landed on the Hudson river in 2009.

EgyptAir said the captain had 6,275 flying hours, including 2,101 on the A320; the copilot had 2,766. The plane was manufactured in 2003.

Airbus said it was aware of the report about the plane but otherwise made no comment.

Is there any suggestion of foul play?

Fathy has conceded that terrorism was more likely than technical failure to be the cause of the crash: “If you analyse the situation properly, the possibility of having a terror attack is higher than the possibility of having a technical [problem].”

The aircraft passed through airports in Tunisia and Eritrea in the four journeys it made on Wednesday before the Paris-Cairo flight, but no warning flags were raised. EgyptAir’s vice-chairman Ahmed Abdel said there were “no reported snags” from the crew in Cairo or Paris, nor was there any special cargo or notification of dangerous goods on board.

The area of the Mediterranean where the plane went missing is heavily trafficked and much monitored, within reach of British listening posts in Cyprus, close to Israel and near to the US Sixth Fleet.

What are the next steps to revealing the aircraft’s fate?

Search and rescue teams will be hunting for a crash site. If they find it, the crews will need to recover the aircraft’s two black box flight recorders.

The water in that section of the Mediterranean can be 2,000 metres (6,500ft) deep – meaning Dubai’s Burj Khalifa tower could fit into it two and a half times. The equipment involved in the search for MH370 is able to search depths of at least 6,000 metres.

If the EgyptAir A320 is the same as the Germanwings model that crashed last year, it will have two recording components: a cockpit voice recorder, which tapes what the pilots say, and a flight data recorder, which stores some of the 2,500 technical measurements in a modern aircraft.

Both are stored at the back of the aircraft and wrapped in titanium or stainless steel, to best survive a crash. They are able to withstand one hour of 1,100C heat and weight of up to 227kg. The boxes can take years to be found – two years in the case of Air France flight 447, which disappeared in 2009 in the Atlantic.

What are authorities saying?

François Hollande, the French president, said: “The information we have gathered confirms, alas, that this plane has crashed, and it has disappeared. We have a duty to know everything about the cause and what has happened. No theory is ruled out and none is certain right now.

“When we have the truth we will draw our conclusions; whether this was an accident or something else, perhaps terrorist. We will have the truth.”

Panos Kammenos, the Greek defence minister, said: “The plane carried out a 90-degree turn to the left and a 360-degree turn to the right, falling from 37,000 to 15,000 feet and the signal was lost at around 10,000 feet.

“It appears the plane is lost. There are no clear results (from the search) so far.”

The Egyptian prime minister, Sherif Ismail, likewise said it was too early to rule out any explanation for the incident, including terrorism: “We cannot exclude anything at this time or confirm anything. All the search operations must be concluded so we can know the cause.”

Serafeim Petrou, the head of Greece’s air traffic controllers board, insisted there was “no chance” MS804 was still in the air. “I consider it a fact that the plane has crashed. There is no chance of it still being in the air,” he said. “Most probably, and very unfortunately, it is at the bottom of the sea.”

“The plane did not give any vocal or electronic signal before it disappeared,” he said, and “nothing can be excluded” on causes: “An explosion could be a possibility but, then, so could damage to the fuselage. I think at this point we are talking about wreckage, wreckage at the bottom of the sea and tracing the cause is going to take time.”

Jean-Paul Troadec, ex-president of the French air accident investigation bureau, said “we have to remain very careful” about possible causes: “We can make certain hypotheses … there’s a strong possibility of an explosion on board from a bomb or a suicide bomber. The idea of a technical accident, when weather conditions were good, seems also possible but not that likely. We could also consider a missile … If the crew didn’t send an alert signal, it’s because what happened was very sudden. A problem with an engine or a technical fault would not produce an immediate accident. In this case, the crew did not react, which makes us think of a bomb.”

The director of Greece’s Civil Aviation Authority, Konstantinos Lintzerakos, said air traffic controllers were in contact with the pilot as the plane passed through Greek airspace, and that he did not report any problems. Controllers tried to make contact again with the pilot 10 miles before the flight exited the Greek Flight Information Range, Lintzerakos added, but the pilot did not respond.

Alain Vidalies, the French transport minister, has said the fact that three of the 10 crew on the flight were security officers is “the usual practice”.

Philip Hammond, the British foreign secretary, confirmed that a Briton was among the passengers, while the Foreign Office in London said it was working closely with the Egyptian and French authorities..