A preliminary report into the August crash of an airliner in Brazil found signs of ice buildup on the plane but no definite cause for the accident, the country’s Center for Research and Prevention of Aeronautical Accidents (Cenipa) said on Friday.
The document pointed out that icing detectors had been activated on airline Voepass’ aircraft, and a Cenipa official told a press conference that cockpit recordings showed the copilot said there was “a lot of icing” during the flight.
According to investigators, that comment indicates that the plane’s de-icing system might have failed, but Cenipa said that information still needed to be confirmed.
Three experts interviewed by Reuters suggested that icing could have played a role in the crash, but urged caution as the report is preliminary and accidents are caused by multiple factors.
The ATR-72 aircraft from local carrier Voepass swirled out of control before plunging to the ground on Aug. 9, killing all 62 on board.
According to Cenipa, investigations into the crash will probably last for over a year.
US aviation safety expert Anthony Brickhouse said: “Everything I have read from the report today is consistent with icing, but accidents are rarely caused by one single event.”
After looking at the report, aviation safety analyst David Soucie told CNN on Saturday that it appeared the crew may have “armed the de-ice boots (on the plane) too soon. Just a few seconds after the de-ice warning,” adding that ice must be allowed to build up on the leading edge of a plane’s wing so it will break off.
“If you don’t let it build first, as in this case, the ice simply builds up in the inflated boot. Then the inflation cycle is under the ice dome and does nothing,” he said, adding that it then gets “heavier and heavier.”
According to officials, loss of speed alerts were triggered, but the ATR’s crew never declared an emergency situation before the plane spiraled down to the ground.
Cenipa officials on Friday also said it is still unclear to them why an aircraft with all necessary certifications ended up losing control and falling. “What we know is that the airplane was flying in an area with severe icing conditions,” said lieutenant colonel Paulo Froes.
The carrier said in a statement that the report confirmed that the aircraft and the pilots were properly certified, adding that the ATR’s required systems were in operation. It added the company would continue cooperating with the investigations.
The turboprop, bound for Sao Paulo’s international airport, had taken off from Cascavel, in the state of Parana and crashed in the town of Vinhedo, some 80 km (50 miles) northwest of Sao Paulo.
CNN has previously reported that numerous videos posted on social media show the turboprop ATR 72 in an apparent flat spin as it spiraled toward the ground with no visible forward movement in what became 2024’s deadliest crash of a commercial airliner.
In-flight icing can “distort the flow of air over the wing and adversely affect handling qualities,” according to Federal Aviation Administration documents, leading an airplane to “roll or pitch uncontrollably, and recovery may be impossible.”
This is a developing story and will be updated.
CNN’s Richard Quest contributed reporting.
