Several pilots headed to the benefit for the Experimental Aircraft Association and the Hagerstown Aviation Museum apparently were unaware of the security measure in part because their antique planes carried no radios.
Meanwhile, at the annual event, attendees were staring at an empty sky, wondering when the show was about to start.
Laura Brown, a spokeswoman for the FAA, said the pilots would not have had the problem if they had been using radios. She said all pilots have a responsibility to check the agency's notifications.
