Airline passengers apparently will find regular fares stable and in some cases lower, but discounts smaller with tougher restrictions on many domestic flights as October begins, according to an unofficial survey of the major air carriers.

As recently as last month, industry analysts and airline officials were predicting improved earnings in 1981 for the airlines as a result of the Professional Air Traffic Controllers Organization strike. The theory was that airlines were being forced to cut back on their flight schedules, so they would be filling more of the seats that remained available. The airlines would be cutting their costs by laying off some employes and winning productivity concessions from their unions. Fuel consumption would fall, and "price wars and discount fares will become a fond and distant memory," in the words of one analyst.

For a variety of reasons, however, price wars and discount fares haven't disappeared:

In a bid to reverse mounting losses and to remind travelers it now has a "National" route system, Pan American World Airways instituted significant "no-strings" fare cuts on the domestic routes it acquired when it merged with National Airlines. Some of the new fares amounted to a 67 percent reduction.

In an attempt to close the widening gap between regular and discount fares, United Airlines announced a major restructuring of its fares that resulted in sharply lower first class and coach fares while raising discount fares.

Fighting for survival amid intense competition on its routes, Braniff Airlines announced a new marketing program that offers all-coach seating and all-discount fares on some flights. Braniff's "express" routes provide discounts of at least 20 percent off coach fares on all seats.

As a result of these actions and the continued lower-fare competition from new airlines, travelers may find some fares significantly lower now than they were a couple of weeks ago. For instance, under Pan American's fare reduction package, its one-way coach fare between Houston and Miami dropped from $238 to $79. Its first class fare on that route dropped from $358 to $159.

Those kinds of reductions are repeated all over Pan Am's domestic route structure, including its Washington-Miami route. Pan Am now is charging $75 for a one-way coach ticket between Washington and Miami Monday through Thursday, and $95 for a coach ticket Friday through Sunday.

United's moves -- followed by American and Trans World airlines -- reduce their fares considerably for the business traveler and others who can't or don't plan ahead, but raise them for the pleasure traveler seeking discounts.

Take the busy New York-Los Angeles route as an example. United pegged its one-way first class fare at $375, down from the $670 it might have been, and its one-way coach fare at $300, down from $478. However, it raised its regular round-trip Super Saver discount fare from $358 to $450.

As a result of United's restructuring, the regular fares between Washington and the West Coast on the major airlines also went down from higher fares scheduled to take effect: the one-way first class ticket was cut from $1,639 to $406 and the roundtrip coach ticket was cut from $457 to $325. At the same time, the regular day round-trip discount fares increased from $358 to $450.

United and the other major airlines were complaining that they weren't taking in enough money because increasing numbers of their passengers were flying on discount fares -- at least two-thirds of United's passengers, for instance. United officials hope the new fare structure will mean more passengers flying at regular and first-class fares and fewer traveling on the stricter discounts -- an outcome that could mean a generally higher average fare level for the major airlines' passengers, and more money for the airlines.

In general, the tightened restrictions on the "super-saver"-type fares require purchase 14 days in advance and a stay over a Saturday night.

Some of the major airlines still respond to the fare moves of another major carrier in lockstep, but some carriers will go their own way.

An example would be on fares from Washington to Miami, where Air Florida offers a $69 one-way fare Monday through Thursday mornings and $89 one-way Friday, Saturday and Sunday mornings, a little lower than Pan Am's. But Air Florida's fare on its other flights to Miami is $125 each way, higher than Pan Am's $75 and $95 fares. Eastern offers a morning flight at $79 Monday through Thursday and $99 Friday through Sunday, but its fare on its other flights is $149 each way.