It's 7 a.m. and still dark when Captain Dan Rosenson pulls on the throttle and his Cessna 172 begins rocking and bucking as if it is eager to get into the sky. But suddenly, ahead on the runway at National Airport, a row of three small lights--the wing tip and nose lights of a commercial jet--pop out of the blackness.

For a moment, it looks like a traffic tie-up in the offing. But then WMAL-AM's airborne traffic reporter deftly does what he spends five hours a day telling rush hour commuters to do: avoid a traffic jam. Cleared by the control tower, he takes off for a Peter Pan tour of Washington that makes RFK Stadium look like a fruit bowl and the Mormon Temple a sand castle.

Rosenson, WASH-FM's Walt Starling and WTOP-AM's Bob Marbourg make up Washington radio's fraternity of airborne traffic reporters. Each makes up to four live broadcasts an hour in morning and evening rush hours while manuevering a small plane above the Beltway and major roads leading into the District.

Describing the daily traffic scene from 1,200 feet above, they advise commuters on accidents, closed lanes, weather hazards and other annoyances along their routes. At the same time they have to look out for obstacles in the air and mechanical problems with their planes, dangers that have claimed the lives of some of their colleagues.

Airborne traffic reporting began as a profession in the late 1950s; former army captain Max Schumacher, first in the field, flew a helicopter while broadcasting for a Los Angles station until his career ended in a fatal crash.

The programs cost each local station more than $100,000 a year today, but airborne traffic reporters are a bonus, station managers said. "Walt's a very important part of what we do," said Earl Murton, sales manager at WASH. Starling appeals to commuters and, Murton said, "radio is a very effective in-car medium."

WMAL's Rosenson, 51, belongs to the nation's first generation of airborne reporters and was the first in Washington, beginning 17 years ago on WWDC (DC-101 AM).

"He's a legend," a fellow traffic reporter said. Considered an authority on area traffic, he is quoted often by the press during periods of unusual road conditions. He often was consulted on the post-blizzard traffic jam last month and gave live reports on ABC television during the Air Florida crash in 1982.

Despite the long hours, weather that is often too rough for pleasure flying and the high density of air traffic in the Washington area, Rosenson said he finds satisfaction in his job.

"I watched them build the Metro system. I watched the first hole being dug," he said. "I've watched the city change, highways built and new buildings going up. From that standpoint it's been fascinating."

He also enjoys his role as "Captain Dan, the traffic advocate."

"I like to look at some of the controversial aspects of traffic, examine arbitrary or unilateral decisons that are made by politicians and traffic authorities that really are damaging to the traffic flow," he said.

Rosenson, a former Army captain, began piloting helicopters for WWDC's traffic reporters in the early 1960s. He began broadcasting when WWDC traffic reporter Marie MacDonald and a pilot were killed in a crash in 1966. In 1980, he joined WMAL, where he began using a plane instead of a helicopter after the station's management decided it was more efficient and economical.

"A lot of people like to make more of this job than it really is," Rosenson said. "I think traffic in itself is fairly mundane. We try to make it a little more palatable." After 17 years on the air and in the air, he said, "I'm sort of looking forward to retirement."

Both Marbourg and Starling said they were influenced by Rosenson to join the profession.

"I listened to Dan on the air when I was 14 and 15," said Starling, 31. "But I didn't think I would ever do what he does." Starling said he majored in radio and television at the University of Maryland but "wasn't sure whether I wanted to be a disc jockey, a reporter or what. And the more I thought about it, the more I wanted to be a traffic reporter. It seemed that Dan was having a good time."

Starling grew up in Hyattsville and attended Northwestern High School. He flies out of College Park Airport, minutes away from his home.

One of the best known broadcasters on WASH, Starling said he likes the freedom the job affords. "There's nobody looking over my shoulder. I decide where to fly. I own my own plane, and I take care of it. It gives me a feeling of independence," he said.

Starling was the first reporter in Washington to use a plane when he began his career nine years ago at WAVA-FM. He bought his first plane while in college, with a loan from his father. "Metro Meteor," his current plane, is his fourth.

Marbourg, in turn, listened to the broadcasts of both Rosenson and Starling before joining them aloft. He began filling in for Starling during vacations and landed the job at WTOP.

Marbourg also likes to play advocate for commuters. WTOP's all-news format appeals to business people and lawmakers, he said, so he uses his reports to impress upon this influencial audience how they can improve traffic.

"The ability to perceive what is happening and then to turn it around and explain it in a useful manner is a challenge to the senses," he said. And he enjoys the intrigue of flight: "There's a romance associated with flying--the silk scarf, the dawn patrol. . . ."

Marbourg, 38, who uses Bowie's Freeway Airport, is the only one of the reporters who doesn't do his own flying. He also is the only one with an on-the-ground partner, WTOP reporter Dave Statter.

Statter, with his car full of radios, can conduct interviews with people involved in accidents and can identify landmarks that are not discernible from the air. Rosenson and Starling fly alone, playing the roles of pilot and broadcaster.

"You have to work at this job in order to conduct it safely," said Marbourg, who never forgets that his predecessor at WTOP, Steve Thompson, who crashed in 1980, spent two months in intensive care and continues to walk with a cane. "I've spent a lot of time looking for the longest hole on golf courses" to use for emergency landings.

Starling also knows the value of golf courses, having twice been forced to land on them in emergencies.

The three reporters are in constant radio contact with each other while in the air.

"We started talking to each other because we found we would all fly around the same accident," which posed a safety hazard, Starling said. They share stories and traffic information, discuss the morning's newspaper and keep each other company as they watch streams of cars pour in and out of the city.

"There are very few people who understand what we're doing up there," Marbourg said. "And how unpleasant it can be after five windy days when you're literally physically sick doing what you're doing. We're the only people who can commiserate with each other about how much we'd rather be on the ground, except we can't afford the pay cut."

"Here comes the sun," Rosenson said through his radio headset to Starling and Marbourg, closing his morning shift. "It's a pretty sunrise."

Starling's plane whizzed by in front of Rosenson's, on its way home.

"Talk to ya later, Wally," the Captain signed off.