Flights were grounded for about an hour Monday when the power went out at Reagan National Airport outside Washington, D.C.
The power was out from 12:30 p.m. until 1:30 p.m., said Courtney Mickalonis, a spokeswoman for the Metropolitan Washington Airports Authority.
The Transportation Security Administration was able to quickly resume screening using a backup generator at two of four checkpoints.
The airport control tower has a backup power source, said Federal Aviation Administration spokeswoman Diane Spitaliere. The FAA barred planes headed to Reagan National from taking off during the outage because power jetways weren't working and there was no way to unload passengers at the terminal.
Planes were allowed to take off from Reagan if passengers had already been screened.
Mickalonis said the problem originated at an airport substation, but the cause of the failure is still under investigation.