HANG GLIDING was going to be the rave of the future, the sport that would put men at par with eagles and, since size and strength are secondary, would let women also "slip the surly bonds of earth" on equal terms.

All of the above has in fact come true over the past decade. The once-daredevil sport has become quite safe, a lot more fun, and no more expensive than skiing. There are septuagenarian and paraplegic hang-glider pilots, as they call themselves, and you don't have to have a license or even register.

Yet the sport is in a steep decline, even in California, and the last local full-time flying school and hang-glider dealership is shutting down.

Sport Flight of Gaithersburg, run by Bob Deffenbaugh and Margo Daniels, was the first and recently became the last certified hang-gliding school in this area, having trained some 8,000 pilots since 1974. But that number means less than it seems, Deffenbaugh said, because "of those, not more than 400 went on beyond the beginner level, and of those, perhaps 200 are still active."

That falloff is largely because most close-in training slopes have been lost to suburbanization, he said. "You may have to drive several hours to a slope, and then the session may be washed out, because good flying weather has been fairly rare over the past few years.

"This isn't like tennis, where a bad backhand is just a bad backhand, or skiing, where even in a total wipeout you're already on the ground; this is flying. It takes a certain amount of dedication to put in the six or eight months of practice, and running around, and just waiting around, that it takes to get in enough flight time to qualify for mountain flying."

Mountain flying. That's when you step off a cliff into the updraft and soar away into the realm of hawk and buzzard. Such a step require nice calculation: Too much wind may turn a cliff launch into a "cliff lunch" -- a heels-over-head backflip -- and too little may lead to a "cliff lurch," an opposite but equally ugly ending.

But such things hardly ever happen anymore; the equipment has gotten so good, and the sport's self-regulation so stringent, that at the current accident rate you'd have to fly a full eight hours every day for more than 25 years in order to be at all confident of killing yourself.

You'd probably die of happiness long before that, to judge from the head-shaking, eye-rolling, hand-fluttering, semi- coherent efforts of members of the Capitol Hang Glider Association to describe what it is that they love about their sport.

This is not downhill coasting, a brief flutter in a meadow. Once you progress beyond the training slopes, you join the fraternity of pilot/poet John Gillespie Megee Jr., whose members top the windswept heights with easy grace and soar on into the high untrespassed sanctity of space. Weather permitting.

"Hang gliding" no longer is an accurate name for the sport, because modern full-support sling harnesses have eliminated the sense of dangling from a kite. "You really feel like the wings are growing out of your body," pilot Denis Scheele said, "and this is active flying, you're flying every minute, like a bird does even when it seems to be soaring on fixed wings." Some of the latest designs allow the pilot to continuously vary the geometry of his kite almost as subtly as an eagle adjusts the angle of his feathers.

Hang gliders now are equipped with instruments that register altitude and the rate of change and so forth, but a pilot also uses all the senses: Searching out the shadow tracks of clouds for the warm air that may boil up behind them; listening to the wind in the wires and the flap of the fabric to judge airspeed, and estimating air density from ear pressure and feel; sniffing for the smell of manure that may mark the edge of a thermal bubble rising from a sunscorched field. Seeking out the great standing waves that often develop in the lee of a ridge, while avoiding the turbulent troughs between them; judging when to abandon a fantastic thermal before it becomes "cloud suck," which can translate a hang glider directly to heaven.

Often the easiest way is just to watch the hawks, and then go and do likewise. Hawks are virtually constant birds of passage along our eastern mountains, and many a hang glider's most memorable flight was one in which he played with a soaring hawk, and the hawk with him.

"It's hard not to get mystic about it," said Barry Brown, 27, of Reston, a fresh-from-Oregon flyer who last weekend startled motorists along U.S. 211 near Flint Hill, where he was doing a few test hops from a steep and muddy pasture in a sleety stinging rain, "to see about the texture of Eastern air." No, he said, he wasn't kidding. "Sometimes I can even taste a storm, in the back of my throat, before there's any other sign," he said. "But I always check with the weatherman anyway."

Washington and Baltimore high-flyers generally launch from High Rock, near Fort Ritchie, Md.; The Pulpit in McConnellsburg, Pa., or from Virginia's Massanutten Mountain. A typical flight is more than two hours, according to Jerry Nielsen, president of Capitol Hang Gliders (which embraces suburban Maryland and Virginia), and there's always the chance of a Truly Big One, such as Nielsen's club-record 60-miler from Hagerstown to the 17th tee of the Fort Meade golf course.

Nielsen was aloft for 41/2 hours, reached 8,000 feet, and became a very thoroughly identified flying object when radar watchers at Baltimore-Washington International Airport called in a chase plane to investigate a UFO just hanging there, a mile and a half up in the sky.

While Nielsen is a compact and muscular 32, his altitude record was soon topped by clubmate Dick Newton, who's twice his age. "This is not a power sport, it's a judgment sport," said Eric Logan, 43, who this month clocked 49 miles from McConnellsburg. "This was my longest flight and my easiest one."

Vic Powell of Arlington, one of the pioneers of hang gliding and still very active, says the sport will survive its current doldrums "because it fulfills the ancient dream of truly free flight," and that it won't be long before somebody more than doubles the present 200-mile distance record by following the track of migrating hawks along the Appalachians.

Hang gliding's already safer than general aviation, and getting safer all the time, Powell said. "When you hear of a hang- gliding accident now, you just ask which rule was violated. Pilot error is 99 percent of it; for a rated flyer, driving to the launch site is more dangerous than the flight."

While there is no law that says you can't go buy a hang glider, teach yourself to fly it and go jump off the mountain of your choice, it doesn't work that way, at least in this region. U.S. Hang Glider Association members or affiliated clubs own or control most of the best launching sites, and before a pilot is permitted to launch he must show his USHGA rating card. In practice this amounts to peer pressure rather than coercion, "because we all know each other, and we all want the sport to stay fun and safe," Deffenbaugh said. "We've managed to police ourselves so well that the government doesn't feel the need to regulate us, and we want it to stay that way."

Compact, self-deploying parachutes have made gliding almost fail-safe, even if used at very low altitude. During a California contest, two pilots collided in mid-air; the kites were mangled and tangled with the pilots strapped and trapped, but their chutes let them down so softly that neither man was hurt.

The only serious local accident in several years happened early this month at McConnellsburg, when a Pennsylvania pilot ran out of altitude and landed in a tree (which is sometimes a better choice than using the parachute when flying heavily wooded ridges) but then fell out of it. He's expected to make a full recovery.

The local club is trying hard to find better training slopes closer to the city, "so more people can get a chance to find out how great gliding is," Nielsen said. "This is so much fun it just isn't right to keep it to ourselves. "We'll do anything we can to help people get started in the sport, and we welcome pilots of any experience level."

If you want to see the sorts of wings a glider pilot is wearing these days, the club will have a display and information booth on the Mall near the Air & Space Museum during this Saturday's Smithsonian Kite Festival.

CAPITOL HANG GLIDER ASSOCIATION -- Call club president Jerry Nielsen at 726-6616 weekdays, 589-4434 evenings and (bad-weather) weekends.