DENVER -- Real aircraft cannot fly around looking for wind shear, but a crew can be repeatedly subjected to wind shear of all kinds in a simulator. The results, even on a simulator, can be frightening.

United captains Bill Carter and Doug Hill took a reporter along for a ride on a Boeing 737-300 simulator to illustrate the survival techniques, feeding its computers with conditions similar to those that destroyed another airliner, killing all aboard. They asked that the exact crash be kept confidential.

With the latest generation of simulators, it is difficult to tell the difference between flying a simulator and a real airplane. Simulators are room-sized enclosures sitting high on hydraulic stilts that mimic every bump and roll of the real thing. Inside, all aircraft sounds are simulated, and the view outside the windshield simulates the sights of flying in conditions ranging from clear air to the inside of thunderstorms.

In this accident, one can hear rain pelting the windshield. And there is thunder. "We would never take off in conditions like this," Carter said.

But true to the real event, Hill took the plane's controls while Carter spooled up the engines. They began racing down the runway.

"Eighty knots," Carter said. About 92 mph.

As the plane passed 127 knots -- the speed that pilots call V1, essentially the point of no return -- the air speed indicator abruptly stopped moving.

"Wind shear!" shouted Carter as he slammed the throttles into the full "firewall" position -- as much power as he could muster.

"Keep it on the runway," he told Hill, who eased the nose wheel back down onto the runway to gain as much speed as possible on the ground -- a maneuver that amounts to "banking energy" for the ordeal ahead. Even with the increased ground speed, the air speed dropped 20 knots -- about 23 mph.

As did the real aircraft in the real incident, the simulator began climbing steeply as it neared the end of the runway, pushing everyone back in his seat. Then came the bad news.

"Decreasing air speed," Carter said.

"Sinking," he said: "200 feet . . . 160 feet . . . 140 feet . . . 80 feet."

"Bring your stick higher," he said. Hill, already fighting his control yoke as if it were a bull in a rodeo, pulled the nose higher into the air as the engines roared.

With that, pandemonium broke out in the cockpit. Lights began flashing and the control yoke began vibrating loudly like a giant rattlesnake -- the "stick shaker" that warns of a stall.

An artificial voice boomed out in a deliberate but loud monotone, "Don't sink! Don't sink! Don't sink!" It was the ground proximity warning having its say.

As all appeared lost, the plane began emerging from the shear.

"Air speed recovery," said someone out of the din.

A later reading of the simulator tapes showed that the plane dropped within 20 feet of the ground before it recovered and took off.

A lot of people died on the real plane, in the days before pilots were trained to survive wind shear. This was just a simulator. But the cold sweat, fast heartbeat and weak knees were not simulated.