Two pilots, not three, will fly the new jetliners that McDonnell Douglas and Boeing are selling, and that fact horrifies the Air Line Pilots Association.

"We're not saying it will be unsafe" to limit the cockpit crew to two, ALPA President J. J. O'Donnell said. "It's just not going to be as safe."

A three pilot crew "is featherbedding, plain and simple," said Tom Riedinger, Boeing's director of marketing communications.

In the midst of all this labor rhetoric, the real safety issue is in danger of getting lost, and it is one of the most interesting and least well understood in aviation. At first glance, it seems obvious that a third skilled person would bring an extra margin of safety to any airline flight, especially during an emergency.

However, there is a growing belief among safety experts who are neutral on the labor question that a third man in today's highly automated cockpits may not have enough to do and may be more of a distraction than a help.

If three-pilot cockpits are required, ALPA will gain 10,000 dues-paying members in the next decade, airline industry sources estimate. ALPA is lobbying hard at the White House and on Capitol Hill to see if it can make that happen.

It is stricly hardball. In a March letter to the Federal Aviation Administration's parent Department of Transportation, ALPA's Robert F. Bonitati wrote:

"Frankly, we see a rather unpleasant confrontation with the administration arising if they permit these planes to be operated with only two crew members. We are currently preparing an extensive media campaign to explain why the third crew members should not be eliminated from the cockpit. As I indicated to you, we prefer to avoid that." The word safety does not appear in that paragraph.

Dr. Richard Sulzer, who studies human factors at the FAA's experimental center in Atlantic City, said, "We have found a lot of pilots with experience in two-man crews who do not want that third man in the cockpit. When you get them away from the union people and ask, 'Do you need him for safety?' they say no."

The most recent crew-involved accidents have involved three-member crews:

On May 8, 1978, a Boeing 727 landed in Escambia Bay, three miles short of the runway at Pensacola National Airport. Three passengers drowned.

On Dec. 28, 1978, while three crew members worried about a malfunctioning landing gear, a McDonnell Douglas DC8 ran out of fuel and crashed six miles short of the runway at Portland, Ore., killing 10.

The midair collision over San Diego on Sept. 25, 1978, which killed 144 people, involved a Boeing 727 with a three-man crew plus another captain riding along in the cockpit. The safety board debated extensively the question of whether a substantial amount of extraneous conversation recorded in the cockpit just before the collision was a contributing factor, but decided that it was not.

Both ALPA and airframe industry representatives are busy running around Washington bearing sets of statstics about airline accidents involving planes manned by two and three-pilot crews. Not surprisingly, the industry statistics show that two-pilot crews have fewer acidents: the ALPA statistics show that three-pilot crews have fewer accidents.

The National Transportation Safety Board, which has generated the data from which both sets of statistics are drawn, considers the accident rates for both size crews to be statistically insignificant. "We don't think the crew size statistics prove anything," a spokesman said.

The question of a two or three-pilot crew is an old issue, going back in the jet age to the first McDonnell Douglas DC9, delivered in 1965. It was a two-pilot airplane, but an airplane that carries fewer than 100 people.

The new airplanes, the ones that ALPA is fighting about now, are the McDonnell Douglas DC9 Super 80, and Boeing's two entrants, the 757 and 767. Those three will carry from 150 to 210 people each, and will be quieter and much more fuel-efficient than the planes they will be replacing.

Advance orders indicate that they will be big sellers with the airlines, which are anxious to cut their fuel costs and to improve their noise problem with litigious citizens who live near airports. McDonnell Douglas has come to bat first with the Super 80. Top FAA officials are in Long Beach now trying to decide if the Super 80 should be certified as airworthy. While several tough aeronautical engineering issues were still on the table Friday, the FAA was also studying the question of crew size. Super 80 deliveries were scheduled to begin this month, but are being delayed while the FAA completes its review.

The Super 80 Douglas Aircraft Division President John C. Brizendine said in an interview, "is designed for two people," not three crew members. Workload for both crew members has been reduced from earlier, smaller DC9s, and "we have had ALPA members in here many times going through it."

ALPA charges that Brizendine promised in 1974 that Douglas would not stretch the DC9 further without adding a crew member. In a 1974 letter to ALPA, Brizendine wrote, "I can categorically state that our company has no intention to build or market a commercial transport of the type discussed . . . configured with a two-man crew cockpit."

Brizendine said a careful reading of his letter would show that he was referring to different, conceptually new aircraft, not the DC9. "I couldn't in good conscience say that," Brizendine said in the interview.

ALPA has to make its stand with the Super 80, because the two Boeing planes will be coming up for certification in the next two years. Both of those are designed with two-pilot cockpits.

"If an airline wants a third crew position, we'll build it that way and give the third guy something to do," said Boeing's Riedinger. But Boeing will seek certification with two-pilot crews.

Automation and redesigned cockpit interiors are cited by Douglas and Boeing engineers as substantially cutting the workload requirements for crew members. ALPA wants the FFA to require testing with two-and three-pilot crews and to pick which one would be safer.

The FFA tests what the manufacturer proposes. If the DC9 is found to be unairworthy with a two-pilot crew, FAA Administrator Langhorne M. Bond said, "my option will be to turn it down, and I will do that if it doesn't comply" with safety standards.

The private view of many in the airframe industry is that ALPA is taking advantage of tough times at McDonnell Douglas, and other difficult technical questions about the Super 80, to make political hay. "They're attacking a cripple," one insider said.

O'Donnell, told of the charge, denied it. "I worry about hurting McDonnell Douglas," he said, "because I think we need three manufacturers [Lockheed is the third]." Nontheless, he said:

"I'm going to meet that airplane everywhere. They're going to have to push that airplane over me."