The official, Don D. Early, ordered that until the end of February, long-time controllers stop providing on-the-job training to less experienced "developmental" controllers.

The usual combination is an experienced controller in prime, with a new one in backup.

Since the strike, it is being used more aggressively to help counter the loss of experienced controllers.

But current equipment usually requires that trainees practice near an experienced controller, who assumes the role of a pilot and watches for controller errors.

The number of airline passengers has nearly doubled since 1978, while the number of experienced controllers has remained roughly the same.

Three new accountants have been hired, as well as an experienced controller, Ms. Hynes said.

Finally, the trainee moves to the control-room floor to work at the side of an experienced controller.

Even now, during this night shift, only about 16 experienced controllers are at the radar scope.

Numerous reasons are offered to explain why the New York metropolitan area is fast becoming the most difficult place to recruit experienced controllers.

According to Mr. Canoles, there are very few experienced controllers to hire.