In the final chaotic moments before Air France flight 447 crashed into the Atlantic Ocean in 2009, it took the captain of the aircraft, who was on a scheduled break, more than a minute to return to the cockpit, despite his two co-pilots' frantic calls for help, black box recordings showed.

Although it was never revealed what delayed Capt. Marc Dubois, two independent sources told ABC News that the 58-year-old veteran Air France pilot was traveling socially with an off-duty Air France flight attendant named Veronique Gaignard.

Jean-Paul Troadec, the director of BEA, the French authority conducting the investigation into the Flight 447 crash, told ABC News that Gaignard was not part of their investigation because the agency was "not interested" in the "private life of the pilot." Troadec added that he did not think Dubois's alleged relations with Gaignard aboard the plane would have played a role in the accident.

Air France 447 was on an overnight trip from Rio de Janiero to Paris on May 31, 2009 when it vanished. The plane crashed into the Atlantic Ocean in the early morning hours of June 1, 2009.

INFOGRAPHIC: Air France Flight 447: Timeline of Events

Black box tapes recovered from the wreckage two years later, in April 2011, revealed that Capt. Dubois left the cockpit for a scheduled nap about four hours into the flight, around the same time Flight 447 was about to enter a severe thunderstorm which other flights had avoided.

Once in the storm, the plane's pitot tube, a critical piece of equipment that tells the pilot the aircraft's air speed, failed, likely from ice crystals forming on it, according to BEA officials who inspected the wreckage. When the pitot tube fails, the Airbus A330's automatic pilot system disengages, shifting control back to the pilot.

According to the tapes, First Officer Cedric Bonin, a 32-year-old pilot who had fewer than 5,000 flight hours under his belt, was at the controls but had never been in this situation before at high altitude. Bonin made the fatal mistake of pulling the plane's nose up, which caused it to go into a deep stall.

Within seconds, the plane was plummeting about 120 miles an hour in the dark, belly first, with the nose slightly elevated.

"It seems that the pilots did not understand the situation and they were not aware that they had stalled," Troadec said.

The co-pilots asked where the captain was and called for help several times before Dubois returned to the cockpit, the black box tapes showed. When Dubois burst in, he found a scene of utter confusion.

"What's happening?" Dubois was heard saying on the black box recordings.

"I don't know what's happening," one of the co-pilots replied.

"I have a problem…I have no more displays," Dubois said.

They never regained control of the plane, and in the confusion, co-pilot Cedric Bonin thought his instruments were wrong. He was so befuddled that he was heard asking, "Am I going down now?"

All 228 passengers and crew aboard Air France flight 447 were killed.

BEA will release its final report on the investigation into the crash on July 5.  Air France declined ABC News' request for an interview, pending the July release of the final report from France's investigation.

Watch "Vanished: the Mystery of Flight 447," on a special edition of " Nightline" TONIGHT at 11:35 p.m. ET/PT