The time has come to "consider" merging the tactical air forces of the Army, Navy, Air Force and Marine Corps, Rep. Jack Edwards (Ala.), ranking Republican on the House Appropriations subcommittee on defense, says.

The fact that a lawmaker such as Edwards is merely thinking about such an action, which he said in an interview is all he is doing, is bound to send tremors through the armed services. Some of the biggest interservice battles have been over who should do what in aviation.

"It's an example of the unthinkable that we have to think about," Edwards said about consolidating the military tactical air forces into one outfit. "Forces would be arrayed against the plan in great fashion," he said.

Edwards, who two years ago headed a successful congressional effort to make the services buy more aircraft spare parts, said he was puzzled why the Navy rather than the Army is developing an advanced vertical takeoff aircraft designated JVX.

"The Army clearly is the helicopter branch of the service," he said. "It seems strange to me that the Navy is the lead agency."

Edwards said Congress and the Pentagon must look for ways to save money through consolidation of duplicative activities, such as tactical air services, to lower the "bow wave" of military spending now building and due to crash over the country later in the decade.

The four services have ordered thousands of new weapons under President Reagan's rearmament program, and the biggest bills for these orders will fall due late in the 1980s.

If the Pentagon does not find a way to lower this bow wave, Edwards said, Congress will. "I guarantee you we'll make a mess of it. I just don't think that the administration can let us run loose with a bunch of cuts," he said.