One question remains: The GAO sleuths may have succeeded in smuggling bomb components past the screeners, but could the materials they carried have created enough of an explosion to bring down an aircraft? Both the TSA and the GAO agree that they could at least generate enough explosive power to cause serious damage to an airplane. But some skeptics question what they call the "flying lab" scenario, which is the ability to assemble a bomb while aboard a plane. TSA spokesman Christopher White said that the agency consulted with experts on whether it's plausible and that "the consensus was that the terrorists would be more likely to hurt themselves than to blow up the plane." Moreover, he said, "there is a tremendous odor generated by these explosives, and the odds are that someone would say, "What the heck is that?'" The GAO's Kutz concedes that it would take 10 to 15 minutes to concoct a lethal cocktail using separate components. However, he still believes that it could be done—after all, that's why the TSA adopted its rules on liquids in the first place. Other experts note that packed planes and crowded airports full of watchful eyes act as a deterrent: As it is, the TSA receives two to three reports a day of disruptive passengers being subdued by fellow fliers or crew.

Even discounting some of the hyperbole surrounding the GAO tests, the results are a reminder that the current checkpoint system remains vulnerable, especially if, as numerous safety experts have warned, terrorists are willing to bide their time and change tactics as security evolves. "Checkpoints are not the most critical part," TSA Director Hawley told Congress at the end of last year. "Our problem is that we are focusing all the attention on that and not [on] the other layers. There are thousands of ways to attack aviation, and if you button down one part, they'll go after another."