The field at the Marine base in New River, N.C., is socked in, and our CH53-E helicopter is making its landing approach on instruments. We are 1,600 feet up and several miles from the landing spot.

A voice calls out compass headings as ground control guides us in, the three engines of the copter whining loudly in our ears, the thump-thump-thump of the rotor increasingly audible as we near the ground. The giant copter pitches and sways as the inexperienced pilot fights the controls.

Suddenly, the airspeed indicator unwinds to zero. Other instruments move wildly. The helicopter plummets. Pilot error has put us into a fatal stall, and the $45 million assault helicopter -- the pride of the Marines and Sikorsky Aircraft -- crashes.

"Freeze!" says the copilot, and time stops.

The engine noise quiets. The motions end with the cockpit still locked in the crazy position it was in at the time of the crash. The instrument readings are frozen.

Calmly, the copilot explains to the rookie pilot that he pitched the nose of the helicopter too high, causing the stall and the certainly fatal crash. The pilot can even order up an instant replay of the crash to find out where he went wrong.

We are nowhere near North Carolina. We aren't even in a helicopter. We're inside a nondescript building in a commercial district hard by Lee Highway in Merrifield, seated in a $10 million helicopter simulator built by a division of Sperry Corp. The pilot is a reporter who usually gets no closer to the cockpit than the nonsmoking section of a 727. The copilot is an instructor. Atari has nothing on this.

Moments after the terrifying "crash," we are again simulating an approach into New River.

"That's the beauty of this thing," says instructor Tom McBrien, taking over the controls and guiding the simulator to a perfect landing. "Rather than going out and crashing a $45 million helicopter, we can do this 10 times and then go out and get a cup of coffee."

A veteran military pilot, McBrien now works for Sperry, training military instructors to use the simulator. The complex device, which from the outside resembles the front half of a helicopter perched on spindly hydraulic legs, is being assembled by Sperry at the Merrifield facility.

Sperry is also building simulators for F18 and EF111 jets and other aircraft at a new plant in Reston. The Reston facility, equipped with 45-foot-high bays to house simulators under construction, also turns out electronic command centers and trainers for Navy and Coast Guard ships, and houses the company's electronic warfare engineers. Sperry employs about 1,000 persons in Reston and Merrifield.

Sperry has been in the flight simulator business for six years. The work is a logical outgrowth of its older naval simulator business and its primary business of computers, which are the key to sophisticated simulators. With a backlog of about $100 million in orders, Sperry is No. 2 in the industry to the pioneer Link simulation systems, a division of Singer Co.

Unlike Link, Sperry has limited its simulators to military aircraft, although company officials do not rule out eventual expansion to trainers for commercial aircraft or, further down the road, spacecraft. Sperry also makes simulators for the M1 tank and other armored vehicles, as well as moving targets for training infantry.

Flight simulators are valuable not just because they don't crash like real aircraft. They also don't burn up fuel like the real thing. It costs about 10 percent of what it would in a real aircraft to train a pilot on a simulator.

"The business got an extra special boost when the energy crunch came in the '70s," says Sperry vice president for flight simulation systems Thomas G. Walkinshaw, who joined the company six years ago when Sperry, as part of its entry into the business, bought out the flight-simulator firm he helped found.

"It's a tough business to start from scratch," Walkinshaw says. "It takes a lot of different disciplines to build a flight simulator." It also takes a lot of time -- about three years for an F18 simulator. As a result, simulators are virtually custom-built, to contracts that usually call for one or two at a time. Sperry turns out about five simulators of various types a year at its Virginia facilities.

The idea of flight simulators goes back decades -- the first one to duplicate motion accurately claimed an old pump organ as a direct ancestor. Many people are familiar with the classic Link simulator for small single-engine planes, which looks something like a closed cockpit with stunted wings on a pedestal and which doesn't do much more than respond to the joystick and rudder pedals.

But the advent of the silicon chip and increasingly sophisticated computer software and hardware has made flight simulators much more realistic. Four computers run the F18 simulator. The "feel" of the controls on a simulator are just like those on the real aircraft, courtesy of a computer that checks control response 30 or more times a second.

Many of the simulators Sperry builds in Reston not only duplicate motions and sound accurately, they even include video images or computer-generated images that allow a pilot to see what any flight situation would look like -- even down to quirks of particular landing fields. And the seat of the F18 simulator includes air-filled bladders and other devices that simulate the G-forces sustained by a pilot in high-speed maneuvers.

"The first one I flew was the old Link with the little blue wings on it," says McBrien. "Compared to this -- well, that was 25 years ago."

Instructors can make the new simulators do just about anything that would occur in actual flight, and even a couple things that might not, such as weather that nobody would fly in. "We can give them a thunderstorm they'll never forget, without risking anything," McBrien says.

Normally, both seats in the cockpit are occupied by trainees, and the instructor sits behind them at a computer console in a small room attached to the back of the cockpit. The instructor can throw hundreds of different malfunctions at a pilot, selecting them on his computer terminal from a list on a cathode-ray tube in front of him.

"You can train in a flight simulator things you could never train in an actual aircraft," says Walkinshaw. "You could give a guy a flameout at takeoff, and if he doesn't do it right you can flame him out again at takeoff until he gets it right."

In addition to monitoring the pilot's performance, the computer can also play it back, so an instructor can review a student's mistakes just as they happened. The computer can also be programmed with preset flight data to give pilots experience with specific situations and so that pilots can be tested against each other on a uniform set of maneuvers. And by "freezing" the action at any time, a student and instructor can review the student's responses to a situation -- and then have the simulator pick up just where it left off.

At the controls, McBrien guides the helicopter to a safe, but bumpy landing at New River. "I wouldn't want to buy beer on that one," he says, recalling an old military tradition. "Actually, I would have to buy the beer." CAPTION: Picture, Instructors Tom McBrien, and Dick Glass "pilot" a $10 million helicopter simulator built by a division of the Sperry Corp. Photo by Frank Johnston -- The Washington Post