complaints there. now, i spoke with the tsa earlier today. i want to tell you -- show you what they told me. they said the tsa has a zero-tolerance for racial profiling and employs multiple checks and balances to make sure it doesn't occur. it's not only discriminatory, they say, but it's an ineffective way to identify someone intent on doing harm. the tsa says they investigated 386 complaints last year of this type. 142 of which came from this mobile app. so i've already downloaded it just in case. >> samuel birk, thank you so much. and speaking of all this travel, everything you need to know, this is cool. cnn is giving you a fascinating behind the scenes look at the world's busiest airport. what we did, we sent more than three dozen of our journalists to atlanta's airport. they went on the tarmac, rode the trains, got this behind the scenes access to planes so you can check the whole thing out. go to cnn.com/atl24. coming up, a mayor handcuffed