The pilot of the chartered plane carrying a Brazilian soccer team told air traffic controllers he had run out of fuel and desperately pleaded for permission to land before crashing into the Andes, according to a leaked recording of the final minutes of the doomed flight.

In the sometimes chaotic exchange with the air traffic tower, the pilot of the British-built jet could be heard repeatedly requesting authorization to land because of "fuel problems”. A controller explained another plane had been diverted with mechanical problems and had priority, instructing the pilot to wait seven minutes.

As the plane circled in a holding pattern, the pilot grew more desperate. "Complete electrical failure, without fuel,” he said in the tense final moments before the plane set off on a four-minute death spiral that ended with it slamming into a mountainside Monday night.

Just before going silent the pilot said he was flying at an altitude of 9,000 feet and made a final plea to land: "Vectors, señorita. Landing vectors.”

The recording, obtained on Wednesday by Colombian media, appeared to confirm the accounts of a surviving flight attendant and a pilot flying nearby who overheard the frantic exchange. These, along with the lack of an explosion upon impact, point to a rare case of fuel running out as a cause of the crash of the jetliner, which experts said was flying at its maximum range.

For now, authorities are avoiding singling out any one cause of the crash, which killed all but six of the 77 people on board, including members of Brazil’s Chapecoense soccer team traveling to Medellin for the Copa Sudamericana finals the culmination of a fairy tale season that had electrified soccer-crazed Brazil.

A full investigation is expected to take months and will review everything from the 17-year-old aircraft’s flight and maintenance history to the voice and instruments data in the black boxes recovered Tuesday at the crash site on a muddy hillside. The US National Transportation Safety Board was taking part in the investigation because the plane’s engines were made by an American manufacturer.

As the investigation continued, mourning soccer fans in Medellín and the southern Brazilian town of Chapéco, where the team is from, were converging on the two cities’ soccer stadiums for simultaneous candlelight vigils. The six survivors were recovering in hospitals, with three in critical but stable condition, while forensic specialists worked to identify the victims so they could be transferred to a waiting cargo plane sent by the Brazilian air force to repatriate the bodies.

Alfredo Bocanegra, head of Colombia’s aviation agency, said that while evidence initially pointed to an electrical problem, the possibility the crash was caused by lack of fuel has not been ruled out. Planes need to have enough extra fuel on board to fly at least 30 to 45 minutes to another airport in case of an emergency, and rarely fly in a straight line because of turbulence or other reasons.

Before being taken offline, the website of LaMia, the Bolivian-based charter company, said the Avro RJ85 jetliner’s maximum range was 2,965km (1,600 nautical miles) – just under the distance between Medellín and Santa Cruz, Bolivia, where the flight originated carrying close to full passenger capacity.

It is also possible the pilot dumped fuel, or a lack of fuel was caused by a leak or some other, unexplained reason.

"If this is confirmed by the investigators it would be a very painful because it stems from negligence,” Bocanegra told Caracol Radio on Wednesday when asked whether the plane should not have attempted such a long haul.

One key piece to unlocking the mystery could come from Ximena Sánchez, a Bolivian flight attendant who survived the crash and told rescuers the plane had run out of fuel moments before the crash. Investigators were expected to interview her on Wednesday at the clinic near Medellín where she is recovering.

"’We ran out of fuel. The airplane turned off,’” Sánchez told Arquímedes Mejía, who helped pull the flight attendant from the wreckage. "That was the only thing she told me,” he told the Associated Press in an interview.

Investigators also want to speak to Juan Sebastián Upegui, the co-pilot on an Avianca commercial flight who was in contact with air traffic controllers near Medellín’s José María Córdova airport at the time the chartered plane went down.

In a four-minute recording that appears to be an audio message to a friend, Upegui described how he heard the flight’s pilot request priority to land because he was out of fuel. Growing ever more desperate, the pilot eventually declared "Mayday! Mayday!” because of a "total electrical failure”, Upegui said, before the plane quickly began to lose speed and altitude in an almost three-minute death spiral.

"I remember I was pulling really hard for them, saying ‘Make it, make it, make it, make it,’” Upegui says in the recording, which circulated on social media. "Then it stopped … The controller’s voice starts to break up and she sounds really sad. We’re in the plane and start to cry.”

Another clue is the crash site itself, where no traces of fuel have been found. Often planes go up in a ball of flames upon impact but one reason six passengers survived was because the plane did not explode.

Agencies