When the last shots of World War II were fired, ration books were among the first things to hit the wastebasket.But a new specter in rationing is looming in an area perhaps never thought of before - airline travel.

T. Allan McArtor, chief of the Federal Aviation Agency, sounded the alarm for potential rationing of airtravel this week, citing massive growth in travel against limited airport space. America's airports are nearing "aviation gridlock" and in the next few years "we'll have to start rationing" the nation's limited capacity to fly, he said.

McArtor predicted that in a few years the United States will see planes in one city unable to leave because they cannot land in their destination city. Other planes won't be able to fly into the first city because these planes are still on the ground.

Understandably, there is no single, quick solution. But as McArtor pointed out, the problem could be alleviated by building more airports, adding runways to existing facilities, and making better use of air space. The last major airport - Dallas-Fort Worth - was opened in 1974.

U.S. airports handle more than 45O million passengers each year in a $57 billion-a-year industry.

As McArtor observed, the irony is that the United States built its productivity on air traffic. If the problem is not solved, the national economy will suffer.

Right now, coping with the flow of air travel is serious. But a crisis point, McArtor said, could be reached as soon as five years.

Americans are used to `buckling up" and meeting emergencies head-on. In this case it may take some innovative thinking - about traveling during slower periods and other measures - to help ease the burden.

But if that and other measures fail, American travelers may find that they can't get an airplane seat. And they may start asking themselves, as people did during WWII gasoline rationing, "Is this trip really necessary?"