If you have flown anywhere recently, chances are you’ve had to stand in some long lines to get through airport security. Travelers are understandably frustrated at the delays, especially those who have missed their flights and had to spend the night sleeping on an airport cot. The TSA is working to hire more screeners to lessen the delays, and in the meantime is pushing people to sign up for their pre-check program, which, after an initial screening, allows people to get through airport security more quickly. Those enrolled don’t have to take off their shoes, or remove their laptops from bags. But this program isn’t exactly taking off. Only 2.5 million people have signed up for this program, far short of the TSA’s goal of 25 million travelers. There is probably good reason for that. First, it costs a person $85 to sign up. It can take months to pass the screening process. And some are waiting in line for hours to sign up for pre-check. Trading in one long line for another seems to defeat the purpose. Plus, not all airlines have systems in place to accept pre-check customers, so they have to stand in line like everyone else. The problem of crowded airports is expected to get worse as summer begins. So in addition to the swimsuit and sunscreen for your next trip, you better remember to pack plenty of patience as well.