Cockpit confusion and ground handlers' inexperience may have contributed to the crash of a Galaxy Airlines plane in Nevada that killed 70 people, federal safety officials said yesterday.

The National Transportation Safety Board said at a meeting it was not ready to accept a preliminary report on the cause of the Jan. 21 crash in Reno and asked for a further investigation.

Strong vibrations shook the four-engine Lockheed Electra turbo-prop shortly after takeoff from Reno's Cannon International Airport en route back to Minneapolis from a Super Bowl gambling junket.

Investigators said the ground crew that prepared the aircraft for flight did not remember whether it had closed a small rear access door, which if left open could have caused vibrations after takeoff.

The door allows access to an air hose used to start the first engine and should have been closed by the person operating the hose, the board said.

When the vibrations occurred, Capt. Allen Heasley, 49, reduced power. And when air speed neared a stall, he ordered a return to full power, but it was too late.

Investigators said at the safety board meeting that Heasley should have let the co-pilot and engineer help troubleshoot while he concentrated on flying the plane.

Instead, co-pilot Kevin Fieldsa, 27, spent critical moments reporting to the control tower on the number of passengers and amount of fuel while the flight engineer, Marc Freels, 24, performed his regular duties.

Investigator Barry Strauch, who wrote the preliminary report, said there was no evidence that the flight crew had been taught that during an emergency everyone should pitch in to keep the plane flying.

Heasley was described by co-workers as a "thorough professional who went by the book, who knew the aircraft in and out . . . a good pilot," Strauch said.

But cockpit conversation just before the crash showed he was "rather haphazard" and didn't delegate troubleshooting activities during the emergency, he said.

Before takeoff, when the ground crew might have spotted the open access door, the captain had to use hand signals to communicate instead of being able to ask them if "everything was buttoned up," an investigator said.

Jim Burnett, chairman of the safety board, said that the vibrations, while not directly causing the crash, contributed to it and that if the flight crew had dealt with the situation properly, "it would never have resulted in an accident."