WASHINGTON — Bowing to pressure from the U.S. Congress to release raw data from an aborted aviation-safety survey, NASA dumped more than 16,000 pages of hard-to-decipher documents onto its Web site Dec. 31.

The data were at the center of a controversy that erupted in October amid reports that NASA had withheld the information to protect the airline industry at the expense of passenger safety.

NASA posted the data on New Year’s Eve at the same moment it began a teleconference with reporters eager to learn what the U.S. space agency had discovered about air-traffic safety by interviewing more than 30,000 pilots between 2001 and 2004.

NASA Administrator Mike Griffin told reporters the agency had not fully analyzed the National Aviation Operational Monitoring Service (NAOMS) data and had no intention of doing so. He said the purpose of the project was to investigate whether weekly telephone surveys of pilots would be a useful addition to the nation’s current aviation safety-monitoring systems.

NASA started NAOMS in 1998 and spent $11.3 million developing and administering the survey before handing it off in 2005 to the Air Line Pilots Association, the world’s largest pilot union. The union discontinued the telephone surveys in favor of less-costly Internet-based survey.

Griffin said NASA funded the project longer than it intended, but he blamed poor program management for pulling the plug without producing and publishing a peer-reviewed analysis of the results.

Griffin called into question the survey’s methodology, noting for example that if the pilot responses were to be believed, aircraft are experiencing engine failure four times more often than reported.

“[I]f someone comes in and says we are seeing four times as many engine failures as are being otherwise reported, it calls into question the reporting mechanism rather than the underlying rate of engine failure, which we believe we understand,” Griffin said.

The surveys also captured unsolicited complaints about pilot fatigue, aircraft maintenance, airport security, air traffic management and other issues.

Griffin, an aerospace engineer and private pilot, said he saw nothing in the survey data that should alarm air travelers.

“It’s hard for me to see any data the traveling public would care about or ought to care about,” he said. “But it’s also not for me to prescribe what others may care about. We were asked to release the data, and we did.”

The Associated Press first requested the data more than a year ago under a federal Freedom of Information Act (FOIA) request. NASA cited several reasons for denying the request for raw data from a discontinued project, chief among them being concerns about compromising the confidentiality of any of the 24,000 pilots who voluntarily participated in the 30 minute telephone surveys.

But a line in NASA’s denial letter all but guaranteed widespread media coverage: “Release of the requested data, which are sensitive and safety-related, could materially affect the public confidence in, and the commercial welfare of the air carriers.”

Griffin disavowed that language during an Oct. 31 hearing on the flap held by the House Science and Technology Committee, and did so again during the New Year’s Eve teleconference with reporters.

“We left the wrong impression, and I didn’t want to see that happen,” Griffin said. “So I reversed that denial and said, nonetheless, we had legal obligations to ensure, again, that pilot confidentiality was protected and that voluntarily submitted commercial confidential information was protected. Those are legal obligations that are part of the FOIA process.”

Griffin had pledged during the hearing that NASA would scrub the data to remove any such identifiers and release the redacted documents before the end of the year. It met that deadline with 11 hours to spare.

House Science and Technology Committee Chairman Rep. Bart Gordon (D-Tenn.) criticized NASA’s handling of the data release and told several media outlets he intends to hold more hearings.

Rep. Brad Miller (D-N.C.), who chairs the committee’s investigations and oversight subcommittee, also expressed displeasure. In a statement, he criticized NASA for heavily redacting the data. “NASA said others can now analyze the data, but NASA scrubbed much of the information that would be important for any analysis,” he said.

Lawmakers want to see NASA take another crack at validating the NAOMS methodology and, if warranted, restart the weekly surveys. The massive $555 billion omnibus spending bill that U.S. President George W. Bush signed into law Dec. 26 directs NASA to submit a plan to Congress before the end of March for “completing the validation of the survey methodology and restarting the NAOMS survey data collection.”

Griffin told reporters he intends to hand the review off to the National Academy of Sciences.

“The fundamental concern that I had at the time of my testimony and still have is that this research work was not properly peer-reviewed at its inception, and the data that was extracted from the survey was not properly validated at its conclusion,” Griffin said. “We have been asked by the Congress in report language this year to perform an assessment of the data, and we will do that. We will be doing that through the National Academy of Sciences to assure independence of the work, but I do remain concerned.”

Brian Berger is editor in chief of SpaceNews.com and the SpaceNews magazine. He joined SpaceNews.com in 1998, spending his first decade with the publication covering NASA. His reporting on the 2003 Space Shuttle Columbia accident was...