Cause of fatal Brazil plane crash remains unknown

An ATR-72 turboprop plane operated by regional carrier Voepass crashed on Friday in a residential area near Sao Paulo, Brazil, killing all 62 passengers aboard. Investigators have recovered the plane's so-called black box containing voice recordings and flight data, with a preliminary report expected within 30 days, the head of Brazil's aviation accident investigation center, Cenipa, said on Sunday. The plane was bound for Sao Paulo from Cascavel, in the state of Parana, and crashed at around 1:30 p.m. (1630 GMT) in Vinhedo, some 80 km (50 miles) northwest of Sao Paulo. The aircraft was flying normally until 1:21 p.m., when it stopped responding to calls, and radar contact was lost at 1:22 p.m., Brazil's air force said in a statement. The plane did not report any emergency. Videos of the event show that the sky was apparently clear when the plane started spiraling in an unusual circling motion. U.S. aviation safety expert Anthony Brickhouse said investigators would look at aspects like weather and examine to what extent the engines and controls were functioning properly, to help identify what caused the loss of control. Videos of the crash analyzed by aviation experts led some to speculate that ice had built up on the plane. On Friday, Voepass said ice was predicted at the altitudes in which the plane was flying, but that it should have been within an acceptable level. Brazilian aviation engineer and crash investigator Celso Faria de Souza said he is almost certain ice caused the accident, judging from the video. ATR-72 planes have experienced issues with icing, with a crash in 1994 in the U.S. state of Indiana killing 68, after the plane was unable to bank due to ice buildup. After that incident, manufacturer ATR improved its de-icing system. In 2016 in Norway an ATR-72 experienced issues after ice accumulated on the plane, but the pilot was able to regain control.<br/>