(CNN)Once again, the world is transfixed by an aviation disaster, after a Cairo-bound EgyptAir flight carrying 66 people disappeared over the Mediterranean early Thursday.
EgyptAir Flight 804: 5 questions you asked and we answered
Right now, there are more questions than answers to what happened to Flight 804 after it took off from Paris' Charles de Gaulle airport on Wednesday night.
Here are the top questions about the disaster that were searched for in Google -- and the best answers we have at this early stage in the investigation.
The flag carrier for Egypt has a checkered safety record, having been the victim of no fewer than eight hijackings, according to the Aviation Safety Network's safety database.
The most recent occurred just two months ago, when a man took an EgyptAir A320-232 hostage with a fake explosive belt, forcing the plane to divert to Cyprus.
The man was motivated by personal, rather than political, issues. He wanted to be reunited with his ex-wife, a Cypriot.
There were no victims of that incident, but a hijacking in November 1985 resulted in 50 passengers losing their lives.
Gunmen said to have links to the Abu Nidal Organization, a Palestinian terror group, diverted the plane after takeoff from Athens. It landed in Malta, where a raid by Egyptian commandos resulted in the deaths of 50 passengers and six hijackers.
In 1999, an EgyptAir pilot flying a Los Angeles-to-Cairo route crashed the plane deliberately into the Atlantic Ocean, killing all 217 people on board.
Reports that the plane's wreckage had been found proved to be false.
An airline official told CNN earlier Thursday that wreckage was found in the Mediterranean Sea. But searchers determined it did not come from the plane.
The Paris-to Cairo-flight was at 37,000 feet when it lost contact overnight above the Mediterranean, shortly before the aircraft was scheduled to exit Greek airspace and enter Egyptian airspace.
Greek controllers had talked to the pilot at 2:48 a.m. local time in Greece (1:48 a.m. in Paris and Cairo), when the plane was near a Greek island, and all had been well.
But at 3:27 a.m. local time (2:27 a.m. in Paris and Cairo), controllers tried to reach the pilots to transfer control to Cairo authorities and received no response.
The plane passed into Egyptian airspace two minutes later, then its signal dropped from radar 13 kilometers (8 miles) south-southeast of Kumbi, an aviation reporting point in the Mediterranean.
The aircraft was cruising at 37,000 feet, considered the safest part of the flight, in clear, calm weather conditions.
Then, upon entering Egypt's airspace, the aircraft swerved then plunged dramatically, Greek Defense Minister Panos Kammenos told reporters in Athens.
"At 3:37 a.m. local time, immediately after the aircraft entered Cairo airspace at 37,000 feet, the aircraft swerved 90 degrees left and then 360 degrees to the right, and descended from 37,000 feet to 15,000 feet and then 10,000 feet when we lost the signal," he said.
While the reason is still unknown -- and aviation analysts stress it is too early in the investigation to make a call -- it is more likely to be terrorism than a technical issue, Egypt's Civil Aviation Minister Sherif Fathy said.
"I don't want to go to speculation. I don't want to go to assumptions like others. But if you analyze this situation properly, the possibility of having a different action aboard, of having a terror attack, is higher than having a technical problem," he said.
"There were no known security issues with passengers on the plane," he said, but added that further checks are underway.
U.S. government officials have told CNN that their early theory is that the disaster is a case of terrorism, with the initial suspicion that the plane was taken down by a bomb.
But they caution that the theory is not based on any concrete evidence -- just the circumstances. They believe the "swerving" reported by Greece's defense minister was most likely pieces of the aircraft that were picked up by radar, which isn't reliable for determining phenomenon like sudden movements.
A distress signal was detected at 4:26 a.m. -- almost two hours after the jet vanished -- in the general vicinity where it disappeared, said EgyptAir Vice President Ahmed Adel.
He said the distress signal could have come from another vessel in the Mediterranean. Egyptian armed forces said they had not received a distress call.
A distress call is how a plane signals there is an emergency -- and doesn't have to be a pilot alerting authorities with a "Mayday" call.
It could be an emergency beacon, a small emergency locator transmitter (ELT) which sends a call to satellites overhead.
It is activated on impact, sending signals to satellites which are then relayed to monitoring stations on the ground.
Hijackers or renegade pilots cannot disable some of the emergency beacons, namely, the ones attached to the plane's airframe. Powered by batteries, they are inaccessible to the crew.
The names of the 56 passengers and 10 crew on board -- two cockpit crew, five cabin crew and three security staff -- have not been released by the airline.
The pilots have been identified to CNN as Mohamed Said Shoukair and Mohamed Mamdouh Ahmed Assem, according to an official close to the investigation and a security source. The sources said Shoukair was the captain and Assem was the first officer.
EgyptAir said in a statement that 30 on board were Egyptian and 15 were French.
There were also two Iraqis and one from each of the following: Britain, Belgium, Kuwait, Saudi Arabia, Sudan, Chad, Portugal, Algeria and Canada, according to the Egyptian aviation minister.
The government of Canada said two of its citizens were on the plane. The reason for the discrepancy wasn't clear, but there is a possibility one or more had dual citizenship.
A spokeswoman for Procter & Gamble confirmed to CNN that one of the company's employees was on board the plane.
Ahmed Helal, director of one of the company's sites in Amiens, France, had been traveling on a personal trip.
"This is a very difficult moment for all P&G people, especially for employees of Amiens' site," said Anne Le Brouster.
"Our priority today is to fully support Mr. Helal's family support during this very difficult time and all P&G employees who are very much affected by this tragedy."