"Where's the airport?"

There was a touch of urgency, possibly even fear, in the voice of Air Canada copilot Claude Ouimet when he asked a Cincinnati air traffic controller that question just three minutes before landing his burning airliner.

Controller Gregory Karam's response was instantaneous and reassuring: "Twelve o'clock and eight miles." Eight miles straight ahead.

That is the only audible evidence of anything less than remarkable calm and professional control in a dramatic recording of Karam talking down Air Canada Flight 797 from 33,000 feet to an emergency landing at Greater Cincinnati Airport at 7:20 p.m. on June 2.

Pilot Donald Cameron, who was flying the plane while Ouimet handled the radio, told reporters in Montreal Tuesday that "we were steered to the airport by the most capable air traffic controller whose voice I have ever heard."

But the worst moment, Ouimet said, came when the two men "couldn't see the airport. At that point I asked myself serious questions."

By the time Ouimet asked where the airport was, the plane had descended through the clouds and the pilots could see the ground. But almost all of their flight instruments had been knocked out as the fire crept forward through the plane from a rear lavatory, destroying one electrical circuit after another and filling the cabin and then the cockpit with smoke.

Twenty-three of the 46 persons on board died of smoke inhalation when they were unable to escape after the plane landed and the emergency doors were thrown open. Federal investigators strongly suspect an electrical fire, but they have yet to pinpoint its source.

Eleven long minutes passed from the time Karam was put in charge of the plane by a regional controller in Indianapolis and told that it was on fire until he was informed by another controller in the glass-enclosed "cab" of the Cincinnati tower that "he's landed."

Those 11 minutes of commands, requests and pregnant silences show an old pro at work. Karam has been in front of the radar screens for nine years.

Other planes were diverted out of the way. The airport rescue team was called, and the cab controller was told when to switch the runway and approach lights to high intensity so Flight 797's crew members could spot a runway they had never used. Cincinnati isn't on Air Canada's schedule, and this flight was going from Dallas-Fort Worth to Toronto.

Most importantly, Karam calmly assessed the steadily worsening situation and gave the plane's crew more and more information as more and more things went wrong.

"Do you have time to give me the nature of the emergency?" he asked after taking charge of the flight.

"We have a fire in . . . the back washroom and it's, uh, we're filling up, uh, filling up, uh, with smoke right now," Ouimet said.

Karam directed two other aircraft out of the way, then noticed that important information about Flight 797 had disappeared from the radar screen. That information--the plane's identification, altitude and speed--is transmitted to the screen by the airplane itself, and its loss meant more equipment was failing.

Karam gave Flight 797 instructions that, he hoped, would restore the information. It didn't work. Then he asked Ouimet to tell him the plane's altitude and heading. Altitude was down to 8,000 feet. But "we don't have any heading anymore," Ouimet said. "All we have is, uh, a small horizon."

A horizon is an instrument that tells whether a plane is going up or down and whether its wings are level or banked, as they would be in a turn.

Most instruments were gone and the crew could not tell in which compass direction they were flying. Directions must come from Karam.

So he began: "If able, turn left."

"Turning left," Ouimet said.

Karam monitored the small dot on his radar screen until it was going in the direction needed to get the plane to the runway. "Thank you," he said. "Stop your turn." Cameron and Ouimet, watching their horizon, leveled the wings and stopped the turn.

So it went, through several turns.

Finally, less than a minute after Karam assured the crew that the airport was straight ahead, Ouimet said: "Okay, we have the airport." Final instructions were given; then it was a matter of waiting. It was 61 seconds from Air Canada's last transmission until the cab controller told Karam, "He's landed."

Occasionally during all of this, another plane in Karam's sector would ask for instructions, and Karam would give the minimum, then return to his primary concern. The National Transportation Safety Board has urged frequently in the past that, in an emergency, all other traffic be removed from the emergency frequency and assigned to other controllers.

The Federal Aviation Administration, which owns and operates an air traffic control system that has been accused of having safety problems as it recovers from the 1981 strike and firing of 11,400 controllers, has in Karam a bona fide if reluctant hero.

So Karam was presented at a brief news conference here yesterday after the tape recordings of the dramatic landing were played in public for the first time.

"I'm not a hero," he told a reporter. "It's not appropriate. I was just sitting there" on assignment. Any other controller could have done it, he repeated.

"The captain of the flight was always very steady, and that helped me a lot," Karam said. Asked if he had tried to steady the crew by keeping his voice calm, he said, "If anything, it was the other way around."

He was never concerned about his ability to handle the problem.

"I knew I could vector direct him to the airport, if he could fly it that far," Karam said. When the plane landed, "I felt good. I didn't know at that time that there were people who didn't get out of the plane."

Karam, 36, never joined the controllers' union and did not strike. He recently completed law school and is starting a "modest private practice," he said. He handled the reporters like he owned them. The FAA brass lined the wall and beamed.