Two federal agencies are arguing over whether a radar supervisor fixing a broken window in an air traffic tower was qualified to advise a pilot approaching the airport in blinding wind-swept rain.

The National Transportation Safety Board is also trying to determine whether the American Airlines pilot was given the correct altitude readings and whether ground-sensing instruments were working.Investigators piecing together the episode agreed that the plane was flying too low as it approached the runway at Bradley International Airport.

Flight 1572, with 77 people aboard, clipped some trees as it descended early Monday, losing power in the two engines momentarily before regaining enough thrust to escape disaster.

The air traffic control tower had been evacuated after wind knocked in a window and water began blowing onto the electrical instrument panels.

When the plane came in, air traffic was being monitored in a nearby control room while the radar supervisor was overseeing repair of the window.

However, the supervisor took it upon himself to tell the pilot something "along the lines of `The runway is clear, you can land at your own discretion,' " Robert Benzon, the NTSB's chief investigator, said Wednesday.

A day earlier, Benzon said the supervisor told the pilot he was "cleared to land at his own discretion." The Federal Aviation Administration refuted such language because "cleared" is a specific air control term meaning that air traffic controllers are taking over decisions from the pilot.

The information was recorded on tape in the air traffic control tower, FAA spokeswoman Sandra Allen said. It was not made public.

The two federal agencies disagree over whether the supervisor was authorized to give the pilot the information that he gave.

Benzon said the supervisor was not authorized to give directions in the tower, but Allen also said the supervisor was qualified to relay the information that he gave: two advisories about runway wind conditions and a wind shear alert.

The plane landed safely just short of the runway, striking some instrument landing system antennae, Benzon said. There was one minor injury during evacuation.

Benzon said investigators were not yet sure how the supervisor's actions affected the landing.