NASA gathered the information under an $8.5 million safety project, through telephone interviews with 24,000 commercial and general aviation pilots over four years. Since shutting down the project because of a shift in funding more than one year ago, the space agency has refused to divulge the results publicly.

Just last week, NASA ordered the contractor that conducted the survey to purge all related data from its computers.

The Associated Press learned about the NASA results from a person familiar with the survey who spoke on the condition he not be identified because this person was not authorized to discuss them.

A senior NASA official, Thomas Luedtke, said revealing the findings could damage the public's confidence in airlines and affect airline profits. The A.P. sought to obtain the survey data over 14 months under the U.S. Freedom of Information Act. Luedtke has denied all requests.

Among other results, the pilots reported at least twice as many bird strikes and near-midair collisions as other government monitoring systems show. The survey also revealed higher-than-expected numbers of pilots who experienced potentially dangerous, last-minute instructions to alter landing plans.

''If the airlines aren't safe, I want to know about it,'' said Rep. Brad Miller, D-N.C., chairman of the House Science and Technology investigations and oversight subcommittee. Miller asked NASA last week to provide information on the publicly funded survey.

The survey aimed to develop a new way of tracking safety trends and problems the airline industry could address. NASA said nothing it discovered in the survey warranted notifying the FAA immediately. At a briefing in 2003, FAA officials expressed concerns about the high numbers of incidents being described by pilots, which were dramatically different from the FAA's own monitoring systems.

Aviation experts said NASA's pilot survey results could be a valuable resource in an industry where they believe many safety problems are underreported, even while deaths from commercial air crashes are rare and the number of deadly crashes has dropped in recent years.

The survey, known officially as the National Aviation Operations Monitoring Service, started after a White House commission in 1997 proposed reducing fatal air crashes by 80 percent as of this year. Crashes have dropped 65 percent, with a rate of about 1 fatality in about 4.5 million departures.