The student pilot was within several miles of highly restricted air space in which he could have been shot down, Federal Aviation Administration spokesman Paul Takemoto said.
The plane is owned by the Vintage Aero Club, a group based at the Smoketown Airport near Lancaster.
A club spokesman says the pilot, whose name wasn't released, got confused and wound up in restricted air space, but not within an inner 15-mile prohibited zone.
"You don't want to get anywhere near that," Takemoto said.
The plane was the same one another student flew to within three miles of the White House in 2005, forcing thousands to flee the White House and other government buildings, the club said. In that case, two men flying to North Carolina got lost and didn't respond to government radio communications.
Military jets were scrambled and shot flares to warn the pilots. That student pilot's license was later revoked.
The pilot in Tuesday's incident had been in communication with security officials, but contact was lost, said Lt. Desmond James of the North American Aerospace Defense Command, which scrambled the helicopters. No government buildings were evacuated.
The plane was escorted to Montgomery Air Park, a private airport near Gaithersburg, Md., and the pilot was questioned by the Secret Service. An FAA investigation is under way.
Information from: Lancaster New Era