But it changed a lower court decision that had reduced each pilot's four-year, four-month prison sentence to community service in the United States.

The federal court said the pilots must instead serve three years and one month in the United States under an "open" system allowed by Brazil law. They do not have to go to prison but have to report regularly to authorities and stay home at night.

It was unclear how the sentences would be applied in the United States. A federal court official said compliance was up to the lower court.

Pilots Joe Lepore and Jan Paladino, whose corporate jet clipped the wing of a Gol Airlines (GOLL4.SA) Boeing 737 that plummeted 37,000 feet (11,278 meters) into the jungle, were held for two months after the crash and allowed to return to the United States.

They were acquitted in absentia last year of all but one of six charges: failure to observe cockpit warnings that the transponder and anti-collision system were turned off for nearly an hour, which meant the Boeing pilots could not see the planes were on a collision course.

A judge in the state of Mato Grosso, where the accident took place, originally gave the pilots prison sentences. But they were commuted to community service to be completed in the United States.

Relatives of the crash victims protested and Brazilian prosecutors appealed the sentence reductions, seeking a prison sentence and suspension of the pilots' licenses to fly.

The pilots have insisted the anti-collision system and transponder were never turned off. They deny any wrongdoing. Their defense had sought to overturn the conviction.

The collision snapped off 23 feet (7 meters) of the Boeing 737's left wing, causing it to spiral out of control and break up before crashing into the Amazon jungle.

The Legacy corporate jet, manufactured by Brazilian aircraft maker Embraer (EMBR3.SA) and operated by Long Island-based ExcelAire, landed safely with minor damage.

It was Brazil's worst plane disaster until a TAM Airbus A320 overran the runway and crashed at Sao Paulo's Congonhas airport the following year, killing 199. The two major accidents within a year triggered efforts to reform Brazil's air traffic control system, which is overseen by the military. (Reporting by Anthony Boadle; Editing by Xavier Briand)

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