More than 70,000 American Airlines customers have missed their flights this year and 40,000 checked bags failed to be loaded on scheduled flights because of airport screening delays, an executive for the airline told a U.S. congressional panel on Thursday.

A shortage of staff and a surge in air travelers have created a nightmare scenario for the U.S. Transportation Security Administration (TSA), with airport wait times in places like Chicago having stretched beyond two hours.

Those 70,000 customers account for just a fraction of the 63 million trips on scheduled flights of American, the world's largest airline, through April, but the number of missed trips is likely greater when including large U.S. rivals Delta, United and Southwest.