Prospects that a measure substantially reducing federal regulation of the airline industry will pass Congress this year appear to have improved significantly in the last few weeks.

Although President Carter didn't get the bill on his desk by summer, as he had overoptimistically hoped publicly, the chances that he will get a measure by the end of the year seem to be good despite what seems to have been snail's pace progress so far.

There now appears to be a growing feeling among both proponents and opponents of change that momentum for the legislation is growing. Observers of the battle over the controversial measure point to several factors:

The Senate Commerce Committee began actual markup of the bill in the week before Congress Fourth of July week recess and tentatively is scheduled to meet again on the measure Tuesday. Sen. Howard W. Cannon (D-Nev.), chairman of the Senate aviation subcommittee and the linchpin of the Senate reform effort, believes the committee can complete action on the bill before Congress begins its August recess.

Rep. Glenn M. Anderson (D-Calif.), chairman of the key House aviation subcommittee broke his silence and pledged action on the measure. "It's apparent to me that there should be some form of regulatory reform," he said just before the recess. He said the subcommittee would take up the Senate measure after finishing a noise reduction bill it is working on, adding "Hopefully, we will get a bill out this year."

President Carter's continuous and outspoken support for the measure, which included hosting and appearing at a recent White House briefing on the subject has convinced many within and outside Congress that the administration considers the bill an important part of its first-year legislative program and an intergral part of the plan to improve the economy through increased competition where possible.

Non-industry lobbying is coming increasingly from members of the Adlioc Committee for Airline Regulatory Reform, a diverse group whose dozen plus members include the American Conservative Union, a few of the groups organized by Ralph Nader. Sears, Roebuck & Co., the National Association of Counties and Common Cause. Their loboying efforts stress what they say are the expected public benefits: lower fares where they are possible as airlines seek to fill nowempty seats with travelers who now cannot afford to fly, increased job opportunities if there are increasing numbers of passengers, and more efficient and profitable carriers relying on the marketplace instead of seeking government aid in times of financial stress.

The alliance appears to be chalking up some success. An all-day seminar sponsored by the Ad Hee Committee for Airline Regulatory Reform June 28 attracted about 250, mostly staff from Senate and House offices.

Gererally the measure being considered would relax significantly the Civil Aeronautics Board's authority to regulate the airlines rates and routes. The transition from strict regulation to an environment in which competitive market forces would play a greater role in determining what variety of fares and services are available to the public is to take place over a period of several years in an effort to minimize problems for the carriers and the public.

The bill the Senate committee has begun work on incorporates the features of two bills: one co-sponsored by Sens. Cannon and Edward M. Kennedy (D-Mass.), and one co-sponsored by Sens. James B. Pearson (R-Kan.) and Howard H. Baker (R. Tenn.). Under the "staff working draft" the committee is considering the current protectionist entry policy of the CAB gradually would be replaced by a much less restrictive one. In addition to opening the doors wider to new carriers, the legislation would give existing carriers the right to expand their systems automatically each year by a certain mileage and number of markets. Smaller carriers would be allowed a greater expansion of their system than the five big airlines and in addition would be protected by encroachments from the larger carriers by provisions limiting competition on their routes.

The measure also would give airlines the right to change their fares, down by as much as 35 per cent and up by as much as 10 per cent without CAB interference on routes where there is some competition. Another provision would allow an optional 20 per cent discount for off-peak fares.

Another section would impose strict procedural guidelines on the CAB to require it to consider every application for new service and take action within 10 months. The board has been accused of delaying interminably applications which seek innovative or low-fare service, such as World Airways's 10-year-old plan to provide coast-to-coast air service for less than $100.

The bill has been drawn to minimize fears that small towns will lose service, even though they generally believe the issue to be a "red hering," as Cannon has called it. The bill guarantees subsidized air service for the next 10 years to all communities listed on any regulated carrier's federal certificate even communities that already have been dropped.

The bill's opponents also raise the specter of airline bankruptcies, lost jobs, increased concentration and higher, not lower fares. In a pep talk to the Ad Hoc Committee's seminar, Cannon rejected some carriers' new arguments that the bill may be too technical to be workable. "What I hear are just new words to an old melody: Protect us from competition," he said.

Congressional sources say the administration's battle for the legislation is being run ably by White House Domestic Council assistant director Mary Schuman. Along with DOT general counsel Linda H. Kamm, Schuman is in the process of meeting with all the senators on the committee and anyone else who is interested. At the seminar sponsored by the Ad Hoc Committee, she stressed that the administration considered passage of legislation "absolutely essential" even though the President has been able to nominate three persons to the five-member agency. The existing statute, protective of the industry, is at fault, she argued, and always would leave room for the kinds of decisions and indecision that have led the Congress to its current debate.

The CAB's new leader, Alfred Kahn, also is planning to be more actively involved in lobbying Congress. Never hiding his "predeliction" favoring as much competition as possible, Kahn told the press last week he was becoming involved on his "own violation" and that the White House had not expected him to.

Besides the interest air travel itself generates, there is interest in the bill outside the aviation committees as a test for regulatory reform generally, "This issue has been studied to death," the recent seminar was told by Sen. Kennedy, who held extensive hearings on the policies and procedures of the CAB several years ago when chairman of the Administrative Practice and Procedures Subcommittee. "If we cannot deal with this issue, where the evidence is so compelling, how are we going to handle further regulatory reform bills."