Enjoy this year's cheap holiday abroad because, in the 1980s, the cost of an airline ticket probably is going to go up - and up.

As the airlines grappled with the crisis posed by the grounding of the DC-10 at the start of the 1979 holiday season, they also were assessing other difficulties for the boom in low-price air travel.

The cost of fuel was one factor, as the Organization of Petroleum Exporting Countries (OPEC) continued to mark up the world price of oil.

"The fuel situation is going to be worse than the airlines seem to feel it will be," said David Kyd, spokesman for the International Air Transport Association (IATA), at a seminar of aviation executives and journalists at this West German resort town.

Captain Werner Utter, operations chief of West Germany's Lufthansa airline, one of the world's largest, said: "We are running into a very hot summer."

Fuel accounts for up to 25 percent of an airline's costs. OPEC raises this year already have forced a fare increase of around seven percent; another similar increase is likely in October. Fuel is also scarce, because of the cut in Iran's production.

"Europe has enough fuel so far," said Captain Utter. "Worldwide, I can also get you fuel anywhere - but at a dollar a gallon, and that is expensive."

IATA's Kyd said his organization, representing 103 airlines, believed "the crunch is bound to come."

The airlines, or governments, would simply have to slow down the phenomenal growth in airline travel.In 1978 the airlines carried nearly 675 million passengers. Some experts say that figure could double before 1990 as more wide-bodied jumbo jets - carrying between 300 and 500 passengers each - are put into use.

Already, the Seeheim seminar was told, the sheer volume of traffic is itself posing difficulties for the aviation industry, which is likely to join with the cost of oil in pushing up fares. Someone, either the taxpayer or the passenger, will have to pay for the enlarged airport facilities to handle the flying millions.

Doubts also exist as to whether air traffic control, at least in crowded West European skies, can cope. Money will be needed for more staff and new equipment.

Malte Bischoff, head of West Germany's Condor charter airline, cited the case of Spain, the main holiday destination for Western Europe.

"You cannot really handle all the traffic they get flying into Spanish air space," he said. "Going in there is like going off the autobahn onto a crowded minor road."

He predicted that Spanish holidays, in particular, would show sharp price rises in the 1980s: "We expect a 20 to 30 percent increase in hotel prices. Fuel will be short in Spain." Dr. Bischoff said that "if the trend continues, Spain will price itself out of the market - except that there is really no substitute for Spain."

Its sunny beaches are close to West Germany, Britain and Scandinavia. It takes 40 percent of Condor's holiday traffic. On any one day during the summer, Condor carries more people to Majorca than it does in six months to the Caribbean.

Executives of the West German flag carrier, Lufthansa, also predicted sharp rises in air fares.

"Cost will drastically increase and fares will go drastically up," said Lufthansa passenger manager Reinhard Bock, who described as "sick" the scramble by airlines to fill empty seats with cut-price standby and advance fares. He said low-fare operators entering the United States-Europe market across the North Atlantic, following Britian's cheap fare pioneer Sir Freddie Laker and his Skytrain, are forcing other airlines to operate on the route at a loss.

"All the new carriers coming onto the North Atlantic must be on a loss. They are just waiting for a few competitors to go bankrupt, then they can raise the fares," he said.

Lufthansa, Bock said, had joined British Airways and Quantas, the Australian airline, in offering cheap excursion fares on the Europe-Australia route, hoping to win more business.

"We are losing our shirt," he said. "The only solution will have to be to get the fares up again."