If the A7 attack plane can survive in the air as it has on the ground for the last four years, Soviet gunners have a real problem.

President Carter did not want the A7, telling reporters in 1977 that the plane was "obsolescent at best" and "ought not to be built any longer."

The Air Force and Navy, the only military services that buy such planes, did not think enough of the A7 over the last several years to devote slices of their budgets to it.

Even President Reagan, in adding $32.6 billion to Carter's fiscal 1981 and 1982 defense budgets, did not allot a nickel for the plane, which is built in Dallas by the Vought Corp., a branch of the LTV Corp.

The A7 is virtually certain to stay in production anyway, thanks to lobbying by the National Guard, Vought and the Texas congressional delegation, which is trying to protect the 2,250 jobs linked to continued production of the plane.

The Air National Guard is pushing its friends in Congress to add money to the Reagan defense budget to buy the last 12 of 42 two-seat versions of the A7, designated the A7K. The Guard says it needs two-seaters to train pilots to fly the one-seater fighting version of the A7 being turned over to its reserve-status groups.

Skeptical congressional staffers point out that the two-seater makes a dandy executive jet for Air National Guard generals as they fly around their states.

Either way, with friends like John Tower (R), chairman of the Senate Armed Services Committee, and House Majority Leader Jim Wright (D), both of Vought's home state of Texas, there should be no problem this year persuading Congress to appropriate more money for the A7.

In 1978, when it was more fashionable to challenge defense spending, three House members got nowhere when they complained that adding $194.6 million to the Pentagon budget to buy Vought A7s for the Guard and $145 million to purchase more Lockheed C130s was a "goody made up of one part plums for Vought Corp., one part pork for the Air National Guard and one part serving both functions in a dual threat mode."

Even after the Air National Guard gets all 42 of its two-seaters, the A7 production line is apt to stay hot. Retired Marine Gen. J. D. Hittle, a Vought consultant, is among those telling influential people in Washington that three fighting versions of the A7 could be bought for the price of one A18, the Navy's new attack plane that is buffeted by cost problems.

"I think their game is to keep the A7 line open any way they can until they can make some foreign sales," said one congressional staffer after hearing Hittle's pitch over lunch.

Pakistan wanted to buy 110 A7s, which can carry a heavy load of guns and rockets for long distances. The Carter administration refused to let Vought close the deal, with the State Department declaring it would "have meant the introduction of a major sophisticated weapons system into South Asia."

President Reagan has indicated that he will be more supportive of overseas weapon sales than Carter was.

Julian Scheer, senior vice president of corporate affairs for LTV, said his firm is offering the Air Force S7s with more powerful engines as a low-cost fighter. But he said the plane is not being pushed as a substitute for the costly F18.

"When the F18 goes into production," Scheer said, "we're going to have to step off the stage." He denied that his firm is lobbying intensively this year to keep the A7 in production, declaring: "You flatter us beyond words." y

Michael Collins, who piloted Apollo 11 around the moon while his two campanions walked on it, is Washington field general for Vought and the A7. John K. Meagher, former minority counsel to the House Ways and Means Committee, is LTV's new vice president for government relations. So the A7 will continue to have effective ground controllers.

"I can't remember a weapon that has kept going so long against such odds," one veteran Senate staffer said.