Significant gaps in security at the nation's airports could be curtailed even at a time of rising passenger traffic by quickly making a wide range of relatively modest changes in screening people and bags, a confidential report by the Department of Homeland Security has concluded.
Fixing serious weaknesses in the nation's aviation security system is critical as passenger traffic rises beyond levels seen before the attacks of Sept. 11, 2001, the report observed. This summer, passengers are expected to take about 200 million trips globally on the nation's airlines, up about 4 percent from last year.
The proposed fine-tuning of airport security includes expanding the use of devices that can detect trace amounts of explosives and stationing more armed guards in secure areas.
''There is increasing pressure to increase the flow of passengers and their property through security checkpoints,'' the report said. ''Unfortunately, our analysis has shown there are significant security gaps at checkpoints as they currently exist.''
Widespread delays caused by security breaches could be reduced by simply preventing passengers from dashing through exits leading from secure areas, the report said. Checkpoints operated by the Transportation Security Administration, the division of Homeland Security that oversees airport security, should have gates or lockable doors at those exits, the report said.
And while the T.S.A. has an agreement with local law enforcement agencies to provide backup, if necessary, the arrangement is not enough, the investigators concluded, because it may take several minutes for an armed response.
''If, say, a handgun were discovered,'' the report says, ''the terrorist would have ample ability to retain control of it. T.S.A. screeners are neither expecting to encounter a real weapon nor are they trained to gain control of it.''
To speed the screening process, the report included some low-tech solutions, like setting up longer tables where passengers disgorge personal items into plastic bins. Because people are often backed up waiting to unload items, investigators found, the X-ray machines that examine carry-on baggage sit idle as much as 30 percent of the time.
Mark O. Hatfield Jr., a spokesman for the T.S.A., said steps were already being taken to speed passengers through airports without compromising security, including expanding checkpoints at airports in Atlanta, Denver and Washington. As a result, Mr. Hatfield said, even though passenger traffic is increasing, the average peak wait time at checkpoints has dropped a minute in the past year, to about 12 minutes.
''Getting as many people through as possible in a way that maintains or improves security -- that's the name of the game,'' he said.
The detailed security evaluation was necessary, the 214-page report says, because government officials made mistakes in rushing to improve aviation security after the Sept. 11 attacks.
''There can be no doubt that their efforts were Herculean, and the resulting system has made the nation safer,'' the report says. ''However, speed always comes at a cost, and the existing system may neither uniformly provide the degree of security desired, nor do it as efficiently and/or in as customer-friendly a fashion as might be achievable.''
The study, prepared at the request of Congress, looks at four areas: passenger checkpoints, checked baggage, air cargo and in-bound international flights. Staff members from the Department of Homeland Security and employees of Northrop Grumman, a giant military contractor, examined 5 domestic airports and 16 foreign ones, looking for quick ways to modify existing operations. The report, by the department's Science and Technology Directorate, was not intended to be released to the public, but a copy was obtained by The New York Times.
The point the report makes is not that the T.S.A. should stop its effort to deploy more advanced technology that can better detect bombs and other threats. It is just that in the interim, the existing technology can be used more effectively, largely to close the most serious gaps.
While the report found ways to improve security and increase the processing of passengers, it said that to accomplish both simultaneously would most likely require additional checkpoint lanes.
Because work on the report has been under way for more than a year, Congress is already moving to provide financing for certain proposals, Homeland Security officials say.
''It is not gathering dust on a shelf,'' Donald W. Tighe, a department spokesman, said of the report, which does not include cost estimates for the security changes. ''It is translating into action.''
The most severe domestic shortcomings involved passenger checkpoints, and included unnecessary bottlenecks and less-than-satisfactory security, the report said.
Checkpoints are equipped with devices known as explosives trace detection machines, in which the screener rubs a swab along a surface to look for minute amounts of explosives. But the machines get only ''limited, undirected use,'' the report found, meaning that a very small percentage of carry-on bags or other items are examined. By adding a single screener to the typical checkpoint, these machines could be used to check the boarding passes, hands and shoes of all passengers.
The additional work could be accommodated in part because some manual tasks could be automated, like moving empty bins back to the front of the line via conveyor belt. As a result, a reconfigured checkpoint used in the study could handle 171 to 179 passengers an hour per lane, compared with the current 183, meaning a major improvement in security without a corresponding slowdown in passenger screening.
Another option to screen better for explosives, Mr. Tighe said, is to install more expensive machines that can detect particles of explosives displaced by puffs of air as passengers walk through them.
Recommendations related to checked baggage include allowing workers monitoring the scanning device to rely more on the computer screen to determine if a suspicious-looking item is an actual threat, instead of the more time-consuming process of opening up the bag.
Air cargo on passenger planes is rarely physically inspected today. Several alternatives were proposed for systems that could handle such a complicated task, given the many different sizes and weights of packages. The House of Representatives has allocated $30 million to Homeland Security for testing such options in the coming year.
Perhaps the most difficult challenge is enhancing security for passengers flying to the United States, the report says. Ideally, the report says, the system should be set up so that ''passengers departing overseas locations for the U.S. can expect the same level of security.''
But the report makes clear that this is not the case. Whatever the shortcomings of the United States system, more severe problems existed at most of the 16 airports in South America, Asia and Europe that were examined for the report.
''Urgent attention needs to be given to some security measures that can be taken very quickly at relatively low costs,'' the report says, recommending, for example, wider use of explosives trace detection machines.
Christopher R. Bidwell, managing director for security at the Air Transport Association, who has seen a draft of the report, said many of the recommendations seemed obvious. But pulling together all of these possible short-term improvements in aviation security is still worthwhile, he said.
''They are not visionary by any means,'' Mr. Bidwell said. ''But they are things that need to happen.''