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Alarming info on plane safety
01/01/2008 12:50 - (SA)
Washington - Nasa grudgingly released some results on Monday from an $11.3m federal air safety study it previously withheld from the public over concerns it would upset travellers and hurt airline profits. The data reflects hundreds of cases where pilots flew too close to other planes, plunged from altitude or landed at airports without clearance.
Nasa published the findings - contained in 16 208 pages - but did not provide a roadmap to understand them, making it cumbersome for any thorough analysis by outsiders. Released on New Year's Eve, the unprecedented research conducted over nearly four years relates to safety problems identified by about 25 000 commercial pilots and more than 4 000 private pilots interviewed by telephone.
The results appeared to reflect in part at least 1 266 incidents in which aircraft flew within 152m of each other, generally considered a near miss; at least 1 312 cases where pilots suddenly dropped or climbed inadvertently more than 91m in flight; and 166 reports of pilots landing without clearance at an airport with an active control tower. The Associated Press matched the data to the questionnaire that was used to interview pilots and was obtained separately by the AP.
Hard landings
The data also reflected 513 reports of hard landings and 4 267 cases of aircraft hitting birds.
Because Nasa scrambled the data, it was impossible to determine whether multiple pilots might be reporting the same incidents, and a key expert said the numbers appeared inflated. Nasa also did not present the data so researchers could project survey results to overall safety trends.
The data that Nasa released was "intentionally designed to prevent people from analysing the rates properly and are designed to entrap analysts into computing rates that are much higher than the survey really shows," said Jon Krosnick, a Stanford University professor and survey expert who helped design the project for Nasa. He urged Nasa to release more of the data needed for a better analysis.
Citing people familiar with the research, the AP reported earlier that the data showed events like near-collisions and runway interference occur far more frequently than previously recognised.
The data was based on interviews with about 8 000 pilots per year from 2001 until the end of 2004. Nasa Administrator Michael Griffin said Monday the survey was poorly managed and told reporters the travelling public shouldn't care about the data.
Deliberately scrambled
"It's hard for me ... to see any data here that the travelling public would care about or ought to care about," Griffin said.
Griffin dismissed suggestions Nasa chose to release the data late on New Year's Eve, when the public is distracted by holidays and news organizations are thinly staffed.
"We didn't deliberately choose to release on the slowest news day of the year," Griffin said.
Nasa drew harsh criticism from Congress and news organisations for keeping the information secret. Rejecting an AP request under the Freedom of Information Act, Nasa explained that it did not want to undermine public confidence in the airlines or hurt airline fortunes.
Griffin later overruled his staff and promised Congress he would release at least some data by the end of the year.
Nasa's survey, the National Aviation Operations Monitoring System, was intended to see whether it could help identify problems and prevent accidents. Survey planners said it was unique because it was a random survey with an 80% response rate and it did not rely on pilots to voluntarily report safety incidents.
Griffin said Nasa never intended to analyse the data it collected, but planned to pass its methodology to the aviation community.
Pilots were asked how many times they encountered safety incidents in flight and on the ground, such as near-collisions, equipment failure, runway interference, unruly passengers or trouble communicating with the tower.
- SAPA
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