A submarine is joining the Mediterranean Sea search for the black boxes that could reveal what caused the crash of EgyptAir Flight 804.
The aircraft disappeared from radar last week on a flight from Paris to Cairo. Searchers have recovered parts of the plane wreckage, including passengers' personal belongings, life vests, aircraft chairs and even body parts. But they're still scouring the Mediterranean for the plane's fuselage, and for the flight data recorder and cockpit voice recorder -- key pieces of evidence that would likely reveal what went wrong on the flight.
Egyptian President Abdel Fattah el-Sisi announced the deployment of the submarine Sunday. It can reach a depth of 3,000 meters (about 9,800 feet), he said.
Authorities haven't said what caused the Airbus A320, which had 66 people aboard, to crash into the sea.
Hours after the flight disappeared, Egyptian Civil Aviation Minister Sherif Fathi told reporters Thursday that it was more likely an act of terror was to blame than a mechanical failure.
But he was more cautious Sunday, urging the media not to jump to conclusions or speculate about what caused the crash.
"In cases like this we need to wait until we base our judgment on facts," Fathi said in an interview with CNN's Becky Anderson. "We cannot at this stage come up with any conclusion."
French Foreign Minister Jean-Marc Ayrault told passengers' families Saturday that "no theory" had been ruled out. No group has claimed responsibility for the crash.
As hundreds of mourners filed into a memorial gathering for the plane's pilot Sunday, his father had harsh words for whoever was behind the crash.
"Whoever took away my only son, may God take the light of their eyes," Saied Shoukair told CNN.
Wake honors pilot
The words of a sheikh reciting the Quran played out from a speaker at a military mosque in east Cairo Sunday as mourners paid their condolences to the pilot's family.
Loved ones embraced outside as friends helped the pilot's frail father walk through the crowd.
Pilot Mohamed Shoukair had more than 6,200 hours of flying under his belt, according to EgyptAir. And his family thought his career as a pilot was only the beginning.
"He had ambitions and dreams," uncle Shehab Shoukair told CNN. "We thought he would one day be a member of Parliament."
The Airbus A320 was carrying 56 passengers and 10 crew members and security when it left Charles de Gaulle Airport in Paris late Wednesday.
Thirty of the passengers were Egyptian.
Also aboard were 15 French citizens, including an infant, and passengers from Iraq, Britain, Belgium, Kuwait, Saudi Arabia, Sudan, Chad, Portugal, Canada and Algeria, said Fathi, Egypt's civil aviation minister.
Automatic messages about smoke
At some point before dropping off radar, the plane swerved 90 degrees to the left and then made a 360-degree turn to the right before plunging first to 15,000 feet, then 10,000 feet, and disappearing from radar, Greek officials said.
French aviation officials revealed Saturday that the plane sent automatic messages about smoke in the front of the aircraft just before it crashed.
France's revelation confirmed flight data that CNN obtained from an Egyptian source. That flight data indicated smoke alerts occurred near the cockpit minutes before the crash.
The data came through the Aircraft Communications Addressing and Reporting System, or ACARS, which sends messages between planes and ground facilities. A screen grab of data has time stamps that match the approximate time the aircraft went missing.
There were indications of problems with a heated window in the cockpit, a sliding window in the cockpit, smoke in the lavatory, smoke in the avionics compartment below the cockpit, a fixed window, the autopilot and the flight control system.
The alerts don't necessarily mean a fire occurred on the plane or that the crew even knew about the alerts, which are automatically transmitted, aviation experts cautioned.
There have been electrical problems with window anti-ice heaters in A320s. In 2003, the Federal Aviation Administration required windshields replaced in all A320s in the United States. It's not known whether Egypt followed the FAA directive.
As of now, investigators have found nothing implicating the flight crew or security officials aboard the plane, an Egyptian official said.
Checks of the passenger manifest have so far resulted in no hits on terror watch lists, officials with knowledge of the investigation said.
The jet had routine maintenance checks in Cairo before it left for Paris, the airline said. Earlier Wednesday, the jet was also in Eritrea and Tunisia, data from flight-tracking websites show.
The Egyptian military said it spotted the debris from the plane about 290 kilometers (180 miles) north of Alexandria, Egypt.
Greece, France, the United States and other nations were searching about 130 nautical miles southeast of the Greek island of Karpathos, Greek aviation officials said.
The European Space Agency said that its Sentinel-1A satellite had spotted an oil slick near where the plane is believed to have crashed. The agency said it's possible the slick could be from another source.
The airline said it will take time to retrieve body parts and conduct DNA tests. Families were asked to provide as much information as possible to identify the body parts. Debris and body parts will be taken to a military base and then to Cairo International Airport.
Recovered parts of the wreckage will be handed over to the state security prosecutor, which is handling the criminal part of the investigation.
The Egyptian Civil Aviation Ministry has formed an investigative committee for the crash led by Ayman al-Moqadem, the investigator also in charge of the inquiry into the October crash of a Russian Metrojet airliner over the Sinai.
The preliminary report of the investigation will be available within a month, El-Moqadem told state media Sunday.
That disaster, which killed all 224 aboard, is widely believed to be the work of terrorists.