The airline pilots union disputes the National Transportation Safety Board's finding that pilot error caused the Northwest Airlines crash in Detroit that killed 156 people last August.

The NTSB in a report on the accident Tuesday faulted the captain and co-pilot of Northwest Flight 255 for failing to follow the proper checklist before takeoff and forgetting to extend the plane's flaps and slats, devices that help provide lift.The McDonnell Douglas MD-80 crashed shortly after taking off from the Detroit airport Aug. 16, 1987, killing 154 people on board and two on the ground. The only survivor was a 4-year-old passenger, Cecelia Chichan.

The two pilots that were killed were members of the Air Line Pilots Association, which represents 40,000 commercial pilots. The union said it will continue its own investigation into the accident and hinted it may petition the NTSB to reconsider the government findings.

"The facts will eventually show that there's a gremlin running around in the MD-80," said Steven Cramer, the ALPA representative at Northwest.

Cramer was alluding to the contention by the pilots union all along that a mechanical failure could have prevented the flaps from being set properly. Even if the pilots forgot to set the flaps, a warning device was the real culprit because it didn't warn the pilots of their error as it was designed to, the union says.

The NTSB said the "overwhelming evidence" was that the two pilots, Capt. John R. Maus, 57, of Las Vegas, and co-pilot David J. Dodds, 35, of Galena, Ill., forgot to set the flaps and slats because they did not properly follow a checklist of pre-flight duties while taxiing before takeoff.

While acknowledging that the accident might have been averted if a warning alert had sounded, the safety board said the failure of the alarm because of an interruption in electrical power was only a contributing factor to the accident.

"The reason for the absence of electrical power could not be determined," the safety board said.

McDonnell Douglas has denied any problems with the circuit breaker and suggested the pilots may have pulled the breaker to keep the alarm from sounding needlessly. The NTSB said it could establish no evidence that the pilots interfered with the alarm system, nor find evidence of a mechanical malfunction.

Nevertheless, the safety board called on the Federal Aviation Administration to begin an investigation to determine the reliability of such breakers and determine if failures within the system can cause such a power shortage.

The thrust of the NSTB's findings, however, was aimed at the performance of the two pilots.

As the plane was taxiing, the captain failed to maintain discipline in the cockpit and did not go through the pre-flight checklists, a formal proceeding that requires the co-pilot to verbally acknowledge that each task is performed, the board said. There was no evidence on the cockpit voice recording that the flaps had been set nor that several other pre-flight tasks had been performed, the board said.

It said that Dodd and Maus had last undergone formal training in cockpit resource management in 1983 when they attended a 31/2-hour training session.

The safety board called on the FAA to speed up its development of guidance to airlines on instituting better training techniques on cockpit procedures and flight crew coordination. While some airlines have such training programs, others do not, said NTSB chairman Jim Burnett.

Among those who sat quietly in the audience at the NTSB proceeding was Allison Maus, the widow of the captain who died in the crash. Mrs. Maus said she felt "very badly" about the NTSB findings "because my husband was a good pilot and he knew it."