Cockpit audio indicates there were problems with de-icing planes during deadly plane crash in Brazil last month, investigators say

SAO PAULO (AP) — The pilots of a Brazilian passenger plane that crashed last month, killing all 62 people on board, reported a malfunction in the plane’s de-icing system, a preliminary report made public Friday showed.

Investigators in Brazil were careful to avoid this as the cause of the accident, stressing that more work needed to be done. Still, their report gave further credence to the leading hypothesis of aviation experts: that the loss of lift was caused by ice forming on the plane’s wings and a failure of the de-icing system.

The weather forecast on the day of the accident predicted icing in the area where the plane crashed.

Audio from the cockpit voice recorder included comments from pilots indicating icing and a malfunction in the defrost system, Paulo Fróes, a researcher at the Air Force’s Center for Air Accident Research and Prevention, told reporters in Brasilia.

Just two minutes before the crash, the co-pilot said, “A lot of ice.”

The plane’s data recorder report also showed that the anti-icing system, which is supposed to prevent ice from forming on the wings, turned on and off several times.

“There are still many doubts. This accident should not have happened, not in the conditions in which the plane was flying and being operated. It had protective equipment,” said Carlos Henrique Baldin, head of the center’s investigation department.

The flight, operated by the airline Voepass, took off from the city of Cascavel, in the state of Parana, on August 9, en route to Guarulhos International Airport in Sao Paulo. The plane crashed into the backyard of a house in a gated community in the city of Vinhedo, about 80 kilometers (50 miles) northwest of the metropolis of Sao Paulo.

Images of the ATR 72 twin-engine turboprop crashing during a flat spin sparked shock across Brazil.

“Based on the preliminary report, it is not possible to definitively confirm that ice on the wings caused the accident, but there are indications that icing was a significant contributing factor,” Henrique Hacklaender, the president of the national pilots’ union, told The Associated Press after the news conference.

Hacklaender said the ATR 72’s de-icing system is manually controlled by pilots, and the preliminary report reveals it was activated during the flight, suggesting an attempt to use it. However, the report does not clarify whether the system was actually used, he added.

The air force center, known as Cenipa, is continuing to investigate the cause of the crash without a set deadline for conclusions. They are also working with an ongoing federal police investigation to determine if anyone is liable for the crash.

ATR is a French-Italian company. The 72 model is generally used for shorter flights. The planes are built by a joint venture between Airbus of France and the Italian Leonardo SpA. Crashes involving various models of the ATR 72 have resulted in 470 deaths since the 1990s, according to a database of the Aviation Safety Network.

It was the deadliest plane crash since January 2023, when 72 people died aboard a Yeti Airlines plane in Nepal that stalled and crashed during landing. That plane was also an ATR 72 and the final report blamed pilot error.

An American Eagle ATR 72-200 crashed on October 31, 1994, and the U.S. National Transportation Safety Board determined that the probable cause was icing while the aircraft was in a holding pattern. The aircraft rolled at about 8,000 feet (2,500 meters) and dived, killing all 68 people on board. The U.S. Federal Aviation Administration issued operating procedures for ATRs and similar aircraft instructing pilots not to use the autopilot in icing conditions.