In the 15 years since Mr. McBroom's plane crashed, United and other major airlines have revamped their pilot training. The emphasis now goes beyond technical skills and memorizing check lists. Crews are trained together. They learn to communicate, to speak their minds, to listen to each other, and to share the tasks of flying the airplane. At America West Airlines even flight attendants are included in the crew training.

Now this attention to teamwork is trickling down to the commuter lines. These airlines are the fastest-growing sector of commercial aviation, with traffic for regional and commuter airlines now five times what it was in 1978, the year the skies were deregulated.

David R. Hinson, the Federal Aviation Administrator, emphasized this growth in testimony to an aviation subcommittee of the House Committee on Public Works and Transportation in February. He noted that the planes operated by the commuter lines were also growing larger and more complex. In 1978, commuter lines flew 20-to-30-seat aircraft a total of 34,000 hours; in 1993, commuter planes of that size flew 591,000 hours.

"Despite the adverse economic conditions that so affected the major carriers over the past several years, the commuters were relatively unaffected, and we forecast that they will continue to outpace the larger airlines," Mr. Hinson said.

The conclusion is inescapable: Morale in commuter-airline cockpits is becoming more and more important to the safety of more and more passengers.

This year, new Federal rules require commuter planes to carry a device that warns pilots when they are too close to the ground. Such warning signals have been required on larger planes for more than a decade.

And the Federal Aviation Administration moved this year to bolster its requirements that all airline pilots, for both large carriers and commuter fleets, undergo regular training to improve cockpit communication.