Widows of two pilots killed in a Kearns midair collision began crying uncontrollably and had to leave the courtroom Thursday afternoon when the man they blamed for the crash took the witness stand.

Air traffic controller Mike Dawson, the controller in charge of SkyWest 834 at the time of the collision, testified that he failed to alert the metroliner of a small, unidentified aircraft nearby before the two collided because he didn't see the small plane on his radar scope.The two planes - the SkyWest metroliner and a privately owned Mooney - collided shortly before 1 p.m., Jan. 15, 1987, killing 10 people.

"I can't sincerely say that the aircraft was or was not on my scope. I just can't say that. But I think if it was there I would have seen it. Someone else in the room would have seen it," Dawson testified.

Dawson was one of five controllers monitoring planes in the Salt Lake tower at the time of the collision. Apparently none of the controllers saw the Mooney on their scopes in the moments before the collision, although playbacks of the Salt Lake tower's radar tracking tapes clearly display it.

Dawson and at least one other controller, Matt Nelson, did see an unidentified craft on their scopes as much as 10 minutes before the collision. Dawson testified Thursday that the unidentified plane could have moved into a position to collide with the SkyWest plane in the 10 minutes that elapsed from the last time he remembered seeing it on his scope.

Attorneys for four pilots killed in the collision claim air traffic control was negligent on the day of the collision because Dawson and others failed to see the Mooney and alert the SkyWest plane of its presence.

They note that air traffic was light to moderate in the moments before the collision - so light, in fact, that the supervising controller left the control room and two controllers - including Dawson - were managing two sectors each.

Plaintiffs' attorneys also claim pilots were having a difficult time seeing other planes on the day of the collision, relying on controllers' "traffic advisories" to alert them of others planes in the sky.

Dawson acknowledged that pilots were having "more difficulty than usual" seeing other planes because of snow-covered ground and haze in the sky. But he said he was very busy in the moments before the collision and did not have time to give many traffic advisories.

Federal regulations require controllers to give traffic advisories after higher-priority duties have been completed.

Plaintiffs' attorney Ed Havas asked Dawson to say the words "traffic 1 to 2 o'clock, two miles, opposite direction, altitude unknown," at the rate and cadence Dawson would normally speak in speaking to one of his planes.

Those words would have alerted SkyWest to the Mooney's presence.

Dawson's rapid-fire repetition of those words took only a few seconds.

Havas then asked Dawson if he wouldn't have had time to add that advisory at the tail end of the eight statements he made to SkyWest in the minutes prior to the collision.

"If I had seen (the Mooney) I could have," Dawson replied.

Asked if he looked at his screen the last time he gave directions to SkyWest, Dawson said he couldn't remember but he probably did because it was his practice to look at his screen when telling planes to change direction.

Dawson's last statement to SkyWest 834 was made nine seconds before the collision when he advised SkyWest to turn left due north (360 degrees) in preparation for a landing approach to Salt Lake International Airport.