SAN FRANCISCO - A small plane with a mind of its own took off by itself and flew for more than an hour before apparently crashing in the woods.
The owner of the single-engine plane told sheriff's deputies Wednesday he had started the engine at the small Two Rock airstrip in rural Sonoma County, then left the cockpit to check beneath the hood.
The plane, a two-seat Aeronca Champion built in 1946 that has a long history of similar incidents, broke free of its mooring and became airborne, sheriff's deputies said.
The plane had less than 15 gallons of fuel, according to the Federal Aviation Administration, and was not expected to stay in the air for too long.
It apparently flew in circles for about an hour before California Highway Patrol officers reported receiving signals from its emergency radio transponder.
The Highway Patrol said the signals were coming from a wooded area 4 miles east of Petaluma. A sheriff's helicopter was unable to spot any wreckage or fire and received no emergency calls about damage or injury caused by the crash, according to sheriff's lieutenant Rich Sweeting.
Authorities said they believed that the transponder signals were from the unmanned plane and said they planned to send up a helicopter to check the area.
A sheriff's spokesman said that the plane's owner, identified only as a San Rafael, Calif., man, was "working on the engine, I guess, and it got away from him."
An Aeronca Champion is a high-wing plane with a 30-100 horsepower engine. Accounts of planes getting away from their pilots are not uncommon. Many of the pilotless planes have been the same Aeronca Champion model.
Aviation experts say the Aeronca Champion is susceptible to such mishaps because of its old-fashioned starting system that requires the pilot to open the throttle and then go to the front of the plane to crank the propeller.