Three Dallas teen-agers, none of them pilots, stole a twin-engine airplane Friday night and took it for a 45-minute joyride, sometimes flying just 50 feet above rooftops and narrowly missing a head-on collision with a Boeing 737 commercial jetliner.

Police said the teen-agers -- two 16-year-olds and a 15-year-old, all from well-to-do North Dallas families -- stole the $25,000 Piper Seneca from Cooper Airmotive near Love Field, which used to be the city's main airport but now serves mostly general aviation. None of the three could fly a plane, but the 15-year-old told his companions he had often watched his father pilot a corporate plane.

He started the plane, taxied onto a runway and took off. The flight went largely unnoticed until a police helicopter, hovering over a private airfield, saw the plane cruising erratically a scant 50 feet above the rooftop of a residential area.

The helicopter pilot said he notified airport officials, who broadcast a warning to other pilots but could not reach the teen-agers by radio.

"Our radio had quit working by then," one of the youths was quoted as saying.

The youth who was piloting the plane had become airsick by that point and was ready for the ride to end, but he didn't know how to land, the three later told police. One of his companions said, "I prayed all the way back to Love Field, hoping we could get down without getting hurt."

Herded by the police helicopter, the plane made its way back to Love Field, crossing the path of Southwest Airlines Flight 89, which was on a landing approach. The Southwest pilot said he watched in disbelief as the smaller plane flew "erratically" toward the jet on a head-on collision course, then dipped beneath the belly of the jet. The youngsters told officers later that they did not see the other plane.

Air controllers, unable to talk to the teen-aged pilot by radio, watched in horror as the light plane made two passes at the runway. The pilot touched down on a third pass, and the plane bounced several times before he brought it under control. A private security guard arrested the three youths after the plane taxied to a stop.

After questioning by Federal Aviation Administration officials, airport security personnel and police, the youths were turned over to their parents, who "were pretty well irritated about it," an airport official said.