The first audio available from the doomed EgyptAir Flight 804 indicates that all was routine as the plane checked in with air traffic controllers in Zurich, Switzerland - and joked with their Greek counterparts - not long before the aircraft crashed into the Mediterranean, killing all 66 on board.
The recording was released as leaked flight data showing trouble in the cockpit and smoke in one of the toilets brought into focus the chaotic final moments of the Airbus 320, which was on its way to Cairo from Paris.
The pilot contacted Zurich late on Wednesday night, before being handed over to Italian air traffic controllers in Padua (Padova).
The Zurich controller says: "EgyptAir 804, contact Padova 1-2-0, decimal 7-2-5, good night."
The pilot responds: "This is 0-7-2-5 Padova control. (Unintelligible) 8-0-4. Thank you so much. Good day, er, good night."
The communication occurred around midnight local time, about two and a half hours before Greek air traffic controllers in Athens lost contact with the plane.
The leaked flight data from Flight 804 includes a three-minute period before contact was lost as alarms on the Airbus screeched, one after another.
Officials say it is still too early to say what happened to the aircraft - France's foreign minister said "all the hypotheses are being examined" - but mounting evidence points to a sudden, dramatic catastrophe that led to its crash into the eastern Mediterranean early on Thursday.
As French authorities question staff who had access to the EgyptAir plane at Charles de Gaulle Airport, cleaning crews are among those drawing attention.
One theory is that a bomb could have been placed in the plane while it was on the tarmac in Paris, or at its previous stops in Cairo or Tunis.
Meanwhile the Egyptian military released the first images of aircraft debris plucked from the sea, including personal items and damaged seats.
Egypt is leading a multi-nation effort to search for the plane's black boxes - the flight data and cockpit voice recorders - and other clues that could help explain its sudden plunge into the sea.
"If they lost the aircraft within three minutes that's very, very quick," said aviation security expert Philip Baum. "They were dealing with an extremely serious incident."
Authorities say the plane lurched left, then right, spun all the way around and plummeted 38,000 feet into the sea, never issuing a distress call.
The Facebook page of Brigadier General Mohammed Samir, the chief spokesman for Egypt's military, showed the first photographs of debris from the plane, shredded remains of plane seats, life jackets - one seemingly undamaged - and a scrap of cloth that might be part of a baby's purple-and-pink blanket.
Brig Gen Samir, later posted a video showing what appeared to be a piece of blue carpet, seat belts, a shoe and a white handbag. The clip opened with aerial footage of an unidentified navy ship followed by a speedboat heading towards floating debris.
Greek officials say the Airbus entered the Athens sector of Greek airspace at 2.24am local time. Twenty-four minutes later controllers chatted with the pilot, who appeared to be in good spirits, quipping in Greek: "Thank you."
At 3.12am, the plane passed over the Greek island of Kasos before heading into the eastern Mediterranean, according to flight data maintained by FlightRadar24.
Less than 15 minutes later, about midway between Greece and Egypt, a sensor detected smoke in a lavatory and a fault in two of the plane's cockpit windows, according to leaked flight data published by The Aviation Herald.
At 3.27am Greek time, air traffic controllers in Athens attempted to contact the plane to hand over monitoring of the flight from Greek to Egyptian authorities.
There was no response from the plane despite repeated calls, including on the emergency frequency. At the same time, a sensor detected that smoke had reached the aircraft's avionics, the network of computers and wires that control the plane, according to the leaked flight data.
Two minutes later, the aircraft reached Egyptian airspace. Alarms went off warning about the plane's autopilot and wing control systems, suggesting serious structural problems. Within seconds, the plane fell off the radar (about 2.30am Egyptian time, which is behind Greek summer time). Air traffic controllers in Cairo sought assistance from the Egyptian air force to track the missing plane - to no avail.