Airline advertising may soon look different. Chances are good that the trumpeted low one-way fares will be replaced in the headlines by the round-trip cost of the journey. And the fares themselves may be higher, because they will include extra charges -- such as the "fuel surcharge" -- that airlines have been adding to advertised low rate.

And you may be told more about strings attached to the low fares; in most print ads, those restrictions will have to be outlined in at least 10-point type, about twice the size of the type you are now reading.

If the change comes about, it will partly result from a controversial law enforcement drive mounted by the attorney generals of the several states.

They say citizen complaints about airline promotions have flooded their consumer complaint offices.

That's something new for the state attorney generals. In the past, they have handled cases against a specific airline ad or a special promotion.

But since mid-1986, the industry as a whole has sparked tremendous consumer anger. Last June, the National Association of Attorneys General decided that they needed to act.

As the task force that was appointed sees it, the trouble stems not so much from the 1978 deregulation of the airlines -- which gave marketers new freedom to develop imaginative pricing schemes -- as from more recent developments.

Its report points the finger at sophisticated computerized seat-sale management techniques, which change from day to day the number of bargain seats available on a particular flight, depending on the number of full-price seats being sold.

And the task force members insist that the concept of a nonrefundable ticket -- at the heart of the most attractive fare schemes -- is such a drastic departure from previous airline ticket policies that customers were not sufficiently alerted to the change.

The advertising that lured travelers in, the attorney generals say, often violated state consumer protection statutes.

The Reagan administration insists that the attorney generals are overstepping their authority.

The 1978 deregulation measure specifically keeps the states out of the business of regulating airline "rates, routes or services."

The Department of Transportation and the Air Transport Association argue that a crackdown on advertising would end up curtailing promotional fares and therefore be an invalid rate regulation.

Federal Trade Commissioner Terry Calvani told the attorney generals that a crackdown on advertising could lead to higher fares that would "get the poor folks out of the skies and back on the bus."

But the attorney generals counter that cheap fares that are so hard to get they are virtually unavailable -- or that have so many restrictions they do not suit particular travelers' needs -- help no one.

What they are demanding, they say, is the same full disclosure they want any advertiser to provide.

To make it clear just what that disclosure consists of, the NAAG adopted detailed guidelines, set to go into effect Jan. 15.

Airline ads that comply are virtually assured of raising no regulatory hackles.

Those that do not are open invitations for court action by individual state AGs. Only Utah and New Mexico indicate they do not go along with the guides.

Under the guides, round-trip prices must be featured, unless the promotional fare is available to one-way flyers, which most are not. The fare has to be all-inclusive. And the restrictions have to be readable.

The attorney generals, responding to complaints from the airlines that broadcast ads cannot in 15 or even 30 seconds spell out all the restrictions, went a bit easier in the guides for radio and television.

If the fare is available for only a limited time or on only a few seats, that information must be included.

So must any limits on refunds. But other kinds of restrictions -- such as demands that tickets be bought well in advance or that fliers stay a certain length of time at their destination -- can wait until a customer calls the airline ticket office.

The states are not suggesting that the ads explain the complicated computer systems that allocate available seats among fare classes.

All they want is a statement like: "This fare may not be available when you call."

The guidelines say that a terse "restrictions apply" or "seats limited" won't do.

Indications are that the airlines will comply.

They, too, are aware of consumer dissatisfaction with some of the difficulties in getting bargain fares.

It's a waste of money to run advertising that readers will not believe.

But not everyone is shouting hurrah. The FTC's Calvani worries that the willingness of the airlines to go along with the ad standards may mask some dissatisfaction of their own with hot-and-heavy competition, and be part of a trend to make low prices in the sky even more scarce.

Moskowitz covers legal affairs for McGraw-Hill World News.