OISSY, France, May 22 -- There is calm once again inside the control towers here at Charles de Gaulle airport just outside Paris.

Air France's decision to do what was once unthinkable -- make its pilots speak English to the control towers -- lasted a mere 15 days.

The airline had the idea that linguistic pride should be put aside for safety considerations. Rather than having bilingual airwaves that frequently confuse and infuriate pilots from other countries, the goal was to have everyone speak English, as happens at many European airports already.

But it wasn't so easy. Last month, the airline was forced to admit that it had underestimated both the difficulties of such a conversion and the stubborn Gallic pride that still persists among French pilots and air controllers.

Some refused to cooperate, and the debate about the subject so dominated the workplace and the airwaves that everyone agreed that no safety benefit was gained. Airline officials say they will have to meet, talk and convince before they try it again.

"We are not asking people to give up the language of Molière," said Pierre Caussade, Air France's director of technical operations, who made the original decision to convert to English and still sounds a bit astonished at how it could all go so wrong. "What we speak in this business is codes and numbers and a shorthand. The goal is not to abandon French but to have a common technical language."

Not everyone saw it that way.

Within days a group of air traffic controllers had organized themselves in opposition. Even before the project began, the headline on the newsletter for Alter, one of the smaller pilots' unions, was straightforward: "English at Charles de Gaulle airport? NO." Keep speaking French as before, the publication urged.

Charles de Gaulle airport at Roissy is the eighth busiest in the world.

There are some people here wondering what Air France could have been thinking. The defense of the French language is hardly a dead passion. There are no fewer than 15 commissions at work in various government ministries here looking for French words to match terms -- usually English -- that threaten to creep into the French language. The government regularly churns out new suggested French terms to substitute for words like "computer chip," "hacker" and "startups."

Far from the frenetic, coffee-gulping, foot-tapping control towers seen in disaster movies, the soundproof control stations at Charles de Gaulle, the world's eighth busiest airport, have a quiet efficiency about them.

Even when planes are leaving one minute apart there is a sense of orderliness.

The controllers watch the screens and the clouds, wearing headphones and holding small black microphones close to their mouths, doling out directions in short, virtually incomprehensible sentences. Then they listen for the pilots to repeat the directions and respond. At some times in the day, about 50 percent of what they say is in English. At other times, only 20.

Most of the controllers have accents in English that would make Inspector Clouseau proud. In fact, almost everyone acknowledges that the level of English among controllers and pilots was one of the underlying problems with Air France's decision. A recent article in Le Figaro said that American air controllers had nicknamed the French flights the "keskidi flights" a reference to the often overheard French phrase Qu'est-ce qu'il dit? meaning, What is he saying?

Patrick LeNoël, an air controller who was at work recently overseeing the traffic on the ground near the B, D and F terminals, said he agreed in principle with Air France's decision. But the 15 days proved that even pilots and controllers, who wanted to go along with the decision, often didn't have the skills yet.

"You know," he said, "with English, the French still have a ways to go. There were a lot of misunderstandings and some were doing it and some were not and in some cases you would speak and they just did not react. The whole thing wasn't well thought out."

Air France did not try a country-wide conversion all at once. Instead it tried to go slowly, only asking its pilots to speak English at Roissy. But some complained that since they spoke English outside of the country, French through the rest of France and then English as they approached Europe's busiest airport, the change was too disorienting.

Meanwhile, air traffic controllers complained that the pilots just did not react when they were spoken to and that time was lost repeating messages.

Officials in charge of the air traffic at Charles de Gaulle say there were no serious incidents in the 15 days that had anything to do with Air France's new language policy. Nor do they believe that there have been any accidents before because of the two language policy. Rather, safety analysts have always maintained that the best policy is a one-language airport.

Some pilots and controllers did not see it that way. "There was a small group whose reaction was very strong," said Jean-Pierre Fremontel, the union representative for the largest air traffic control union at Charles de Gaulle.

"This was a technical decision but some were shocked by the symbolism of being asked to speak English in their own country," he said. "They did not like that at all. The airline was looking at the problem far too narrowly, overlooking the political significance."

Soon both pilot and air traffic control unions asked Air France to back down.

"For the first few days, the controllers said, 'O.K., it's a little difficult but getting better,' " said Jean Jezequel, the manager of air traffic control at the airport. "But then we began getting comments that it wasn't working at all. It was bringing tension into the control room and the controllers were saying that sometimes they just didn't know what language to use."

Mr. Jezequel and other officials say they will be studying all the data they collected in the 15 days to take a look at what happened. "It is a problem a lot less simple than it looks."

Mr. Caussade from Air France says the airline will try again soon. But Mr. Fremontel, the union official, says it won't be easy.

"They were made to go backward and it's not easy to turn that around," he said. Copyright 2000 The New York Times Company