Al Cantello, 48, figured he owned Rte. 50. As the Naval Academy's cross country coach, he made almost daily trips up and back from Annapolis in his green Academy car to meet new recruits at the Beltway train station.

On Tuesday, Cantello was behind schedule. He picked up speed, and sprinted toward the station for a 2:15 p.m. appointment.

In the air, 800 feet above him, a Marland State Police Cessna 182 Skyland circled over the intersection where Rte. 50 meets Rte. 197 Traffic was light. Trooper Bruce Tanner pressed his nose against the window of the plane. He spotted Cantello's car. "That one -- the green one," he called into his radio.

Tanner activated a timing device in the airplane. A small VASCAR computer displayed the number "66" on a digital screen. Tanner announced the spped -- 11 miles over the posted 55 m.p.h. limit -- to the trooper below.

"Arrest the car in lane No. 2, "Tanner said. The trooper drove his unmarked car into position.

Cantello did not notice that his automobile already had crossed over two white lines painted one-quarter mile apart on the highway.

"I see this guy waving me over," Cantello recalled. "I'm courteous. I'm deferential. I give him all the motherhood and flag I could. Then he explains to me that I was pinched for speeding by a plane. I coulnd't believe it."

Cantello got a warning for his excessive speed. Other drivers haven't been so lucky.

"I would have really been angry had I gotten a ticket," Cantello said. "I'd be up there with Snoopy trying to shoot the son-of-a-gun down. I mean, you don't have a . . . prayer."

Maryland state police, it appears, have created the ultimate, fool-proof speed trap; the airborne "Smokey." Truckers who find it a nuisance call it "The Flytrap" or "Bear" in the Air." But no fuzz-buster can stop it.

"I hope you crash," one frustrated trucker called up to the pilots on his CB radio.

The program to nab Maryland speeders by airplane went into effect in August. Trooper Tanner and his pilot, Cpl. Marvin Glawe, spend four hours a day flying in random patterns over a maze of Maryland highways. They usually identify 15 to 20 speeders per hour, compared to road traps, which usually snare 30 speeders per hour.

With the aid of a VASCAR computer (visual average speed computer and recorder) located on the dashboard of the plane's cockpit, the "Flytrap" has made 540 arrests in the last five months, nabbing the unsuspecting drivers of cars, tractor trailers, one bus, five motorcycles and two recreation vehicles.

"It is more effective in getting the type of speeders you would not normally get," said Dan McCarthy, spokesman for the Maryland State Police. "Those with radar detectors, the CB people, the fuzz-busters. Because the plane is high enough, it's as devious as they are."

Tanner explained that quarter-mile sections of the roadways have been marked off with white lines painted perpendicular to the center line. The pilots watch for cars below them that appear to be moving faster than the pack. When the car crosses the first white line, Tanner begins "timing" it. When the car reaches the end of the quarter-mile and crosses the second line, Tanner stops the timer and VASCAR quickly computes the driver's average speed.

In actuality, the troopers said, VASCAR -- which depends on a visual sighting -- is fairer to the driver. While radar traps on the ground measure the driver's top speed. VASCAR computes the average speed.

"If we clock someone at [an average of] 69," Tanner said. "He proba- [TEXT OMITTED FROM SOURCE]

When the unmarked police car on the ground is alerted by the airborne team, they nab the hapless speeder. Most of those pulled over are astonished to hear they have been caught by an airplane.

"I couldn't believe it," said coach Contello. "I felt like Cary Grant in 'North by Northwest.'"

The troopers tell of one startled woman who was caught speeding on Rte. 83. "Oh, I'm so excited," she reportedly told the arresting officer. "I've never been stopped by a plane before. I can't wait to tell all my friends."

But other are not so thrilled.

"I'm not sure that it would hold up in court," said Michael Rowe of College Park, another "Flytrap" victim. "The guy in the airplane couldn't possibly see my license plate from the air. How was he sure it was me?"

The airborne VASCAR program was funded through an $80,000 federal highways grant, which was used to purchase the airplane.Originally, a helicopter was used, but a $100 per hour it was decided that the chopper was too expensive. The plane, according to the troopers, costs approximately $20 an hour.

Judges in Prince George's County district court already have heard four cases of speeders who decide to challenge their citations from the sky. All four were convicted of speeding and were fined approximately $35 each.

State Police say their policy is to advise each speeder how they were spotted by the plane, pointing up to the "Flytrap" in the air. It works, Tanner says, as a future deterrent.

Once, however, the airborne team radioed the necessry information to the tropper on the ground and then took off. It was the end of the day, and the "Flytrap" was on its way home to Martin State airfield in Baltimore County.

By the time the trooper caught up with the speeder, the airplane was gone. But the trooper tried to explain, anyway.

"The kid looked up and didn't see anything," according to Tanner. "He probably thought that the officer was giving him the fast shuffle."