WHITE PLAINS, June 22 - The first hint that something was amiss early Wednesday at the Westchester County Airport was the erratic motion of the low-flying Cessna. Confirmation came moments later when security workers approached the aircraft and beer cans fell out of the cabin as the pilot opened the door.

It was the denouement of what turned out to be a bizarre airborne caper, one that set county and law enforcement officials into a frenzy of finger-wagging, with a new symptom in Westchester's under-age drinking epidemic and Sept. 11-style alarms over airport security.

According to Thomas Belfiore, commissioner of the Westchester County Department of Public Safety, the 20-year-old pilot, Philippe Patricio of Bethel, Conn., stole the airplane from the Danbury Municipal Airport in Connecticut some time after 1:30 a.m. and took two friends, both 16, on a joy ride. Mr. Patricio had taken several flying lessons, but he does not have a pilot's license, Mr. Belfiore said.

Low on gas and lost, Mr. Patricio, whose blood-alcohol level, 0.15, was almost twice the legal limit for driving a car, happened to find the county airport even though it was closed because of construction and the runway lights were off. He landed the plane at 4:15 a.m. on a taxiway, with the only light being that of the moon and lights from airport buildings.