Airline passengers are now increasingly being patted down, and carry-ons are being double-checked since a self-proclaimed terrorist tried to bring down a passenger jet headed to Detroit on Christmas Day. Canine teams are out in force, sniffing for explosives.
Starting this past weekend, more international flights bound for the United States have had plainclothes air marshals mixed in with passengers. Extra teams of specially trained security officers have been roaming airports looking for tells among the passengers — furtive glances or people who nervously open and close bags repeatedly.
In ways large and small, the Department of Homeland Security, once again, is struggling to strengthen an aviation security system it has already spent $40 billion rebuilding since the terror attacks of 2001.
This latest round follows years of effort that has created a security net that is much stronger in key areas, from simple things like secure cockpit doors to the routine inspections now done on checked baggage.
But a review of government audits and interviews with experts inside and outside the government also shows that the system has been slow to make even bigger changes because of a balky bureaucracy, fickle politics and, at times, airline industry opposition. It has also squandered tens of millions of dollars on faulty technology, like high-tech “puffer” machines that repeatedly broke down and flunked the most basic test: they failed to detect some explosives.
As a result, the government has delayed putting in place some of the most important recommendations from the Sept. 11 commission report, which examined the missteps that led to attacks on the World Trade Center and the Pentagon in 2001.
For example, the government has yet to fully deploy a sophisticated method of matching passenger names with terrorist watch lists. And it has still not finished changes that would make it harder for terrorists to sneak bombs into airplane cargo holds, according to government reports.
Officials from both the Obama and Bush administrations argue that the progress is real, and they contend that with additional steps since the Christmas incident, and others under way, a robust security network is in sight.
“You are going to have things that worked and some that don’t work as well as you would have hoped,” Gale D. Rossides, the acting director of the Transportation Security Administration, said in an interview Monday.
“But today’s aviation security in the United States is stronger than it has ever been,” Ms. Rossides continued, “and it is going to continue to evolve to advance the use of technology to address the threats we face.”
But even the administration acknowledges that Friday’s nearly successful attack was evidence that flaws in the system remain.
And many outside critics contend that the government is too quick to rely on technology that may calm the public, but that terrorists can quickly outsmart.
“It is not just the billions of dollars, but the billions of hours people have spent in airports that have been wasted,” said Andrew R. Thomas, editor of the Journal of Transportation Security. “There is no way we have gotten what we paid for.”
Already the most recent escalation of security, particularly for flights headed to the United States, is raising tempers, not just among passengers, but among airline executives who argue that the T.S.A.’s newest rules have hampered their ability to operate.
Air Canada, for example, which like many other airlines saw its schedule disrupted over the weekend, said it was forced to cancel selected flights to the United States beginning Monday because of “protracted waits for customer security clearance at Canadian airports.”
Duncan Dee, the airline’s chief operating officer said: “Our No. 1 priority is the safety and security of our customers and staff. Unfortunately, the delays are being caused by matters entirely outside our control.”
No one seriously disputes there have been big changes since 2001.
Approximately 45,000 professional screening officers have been hired by the federal government. More than 1,600 machines that function like a doctor’s office M.R.I. have been installed at airports nationwide to inspect checked baggage. Another 900 of the machines that scan carry-on bags at passenger checkpoints have been upgraded, to make it easier to find hidden weapons or explosives.
Hundreds of additional canine teams are in place at some of the nation’s 450 commercial airports, and nearly 2,900 of the transportation security officers have been assigned to so-called behavioral detection teams that observe passengers headed to flights for possible hints of terror plots, a strategy adopted from Israel.
But the glitches have been consequential as well.
After the August 2004 bombing of two domestic Russian passenger aircrafts by suspected Chechen rebels, T.S.A. officials rushed to install a new generation of machines, costing $160,000 each, that blew puffs of air on passengers, to sniff for traces of explosives. A total of 207 of the machines were bought, and they were billed as a dramatic improvement to air security.
But even before the machines were all installed, the program was abandoned, as dusty airports caused the highly sensitive equipment to break down too often. They also were not as effective as expected in finding bombs. More than $20 million was wasted on the effort, for equipment alone.
The T.S.A. is also years behind schedule on a plan to take over the process of matching passenger names with the terror watch list, one of the most important recommendations of the Sept. 11 commission. Historically airlines did the matching, and the commission complained that they were not as diligent as the government and did not have instant access to the government’s most up-to-date watch lists.
So far 18 of the about 80 commercial carriers have switched to a government-run new system; 27 others are still testing it.
In recent days, Kip Hawley, the former T.S.A. director, and Michael Chertoff, the former homeland security secretary, have called for the rapid installation of a new generation of whole-body scanners that can look underneath clothing to search for hidden weapons or explosives, which officials consider the single most significant aviation threat today. Such a system might have caught the suspect in the Detroit case, since he had explosives sewn into his underwear.
Mr. Chertoff, in an interview, said that the original plan was to use these devices for all passengers at checkpoints, but that opposition from privacy advocates had significantly delayed the effort. Today, just 40 such machines are in place, compared with the 2,200 checkpoint lanes nationwide.
The agency has plans to install 150 additional machines starting early next year and then to buy 300 more.
But the plan could still be slowed, or blocked, by privacy advocates who have heavily lobbied Congress.
Jay Stanley, of the American Civil Liberties Union, said the machines — which produce chalky images that look like X-ray vision — are an invasion of privacy. He contends that they should not be used on all passengers, just on those who are subject to extra scrutiny.
Jeffrey Addicott, the director of the Center for Terrorism Law in San Antonio, argued that the emphasis should be on improving intelligence to prevent terrorists from getting onto planes, not to find bombs at checkpoints.
“If you are trying to stop these people at the airport, you are too late,” Mr. Addicott said.
Transportation security officials said that a combination of intelligence and equipment was needed, as well as a security system that is constantly changing, so that would-be terrorists could not be certain what kind of scrutiny they would face.
But in the end, both Mr. Hawley and Mr. Chertoff say that this system will never accomplish everything people seem to hope for: total safety from terrorists.
“It is a fool’s errand to try to make the aviation system terrorist proof,” said Mr. Hawley, who helped start the T.S.A. and then ran it until this past January. “The only way to do that is ground the airplanes.”