The next morning, when we report to our classroom in a nearby office building, our numbers have already dwindled: There are twenty of us, ranging in age from early twenties to early sixties and including a retired air-traffic controller, an emergency medical technician, a former hotel concierge, and several college students and laid-off airline workers. Our diversity is largely a function of our status as part-timers—in fact, the airport hasn't had any full-time openings in several months due to budget constraints. The part-time hiring spree that brought me and the others in was supposed to help airports fill staffing shortages after Congress cut the national full-time screener workforce from a high of sixty thousand in 2003 to forty-three thousand today. But apparently at big airports like mine, it's not having the desired effect: Turnover among part-time screeners can be as high as fifty percent, about double the rate for screeners overall. Within a few days, I learn what could be at least part of the reason for the high turnover: Some trainees confess that they hope to use the screener post as a springboard to an easier job with better hours at another federal agency, such as the Customs Service, and that they aren't planning a career with the TSA.

Joe, our training instructor, is an Army veteran and a former marketing executive who joined the TSA after he lost his job in the aftermath of 9/11. "It is really important for us to remember that day," he tells us on our first day of training. "Keep it in mind when things get hard on the job. Don't let complacency get in the way."

This is more than a mere pep talk. I soon learn from current screeners that management has been on edge lately: The TSA's much feared Red Team recently made an appearance, and it seems the results were less than stellar. The Red Team is a cadre of undercover inspectors who test screeners' mettle by attempting to smuggle weapons and other illicit items past checkpoints; those who fail to spot the contraband get sent back to class for remedial training. Test results are supposed to be confidential, but dismal scores from several airports, including Newark and Orlando, were leaked to the media last year: More than half the screeners tested reportedly flunked one of the exercises.

I also learn that because of the staffing shortage, our airport has, in the words of one official who works there, "held on to bad apples probably longer than we should have." An airport theft ring involving screeners was uncovered in the area several years ago. Now, I'm told, airport officials are pushing to rush recruits through training and on to the job so they can begin to clean house. Mass firings are rumored to be in the works.

The job seems more daunting each consecutive day, as we're taught to navigate the uneasy nexus of security and customer service. On the wall of the training room is a constant reminder of how we'll be expected to straddle both worlds: A slick poster bearing the I AM TSA logo and the portrait of an attractive screener—part of a new in-house campaign to humanize us—hangs beside a crudely drawn rendering of a skull and crossbones signifying our mandate to keep bomb components and terrorists off planes.