The Civil Aeronautics Board and United Airlines, the largest airline it regulates, both announced strong support this week fro new draft legislation which would reduce the CAB's hold over the industry.

Also this week, Transportation Secretary Brock Adams began to lobby on Capitol Hill for the administration supported measure, meeting with three key senators, starting with Commerce Committee chairman Warren G. Magnuson (D-Wash.). In the works, sources say, are letters from Adams to governors of the 50 states urging them to actively support the bill.

The measure currently being considered would reduce federal regulation of the air industry over a transition period in order to allow the carriers greater freedom in making their dicisions on where to fly and what to charge.

Although the Commerce Committee made little perceptible progress during the two public markup sessions this week. Aviation Subcommittee chairman Howard W. Cannon (D-Nev.) expressed some confidence that the progress during the three sessions scheduled for next week.

The committee has so far reached tentative agreement on sections revising CAB procedures, settling up a mandatory deadline system for consideration and resolution of matters coming before the board and outlining federal and state air regulation relationships. The committee made progress last week on provisions which would guarantee service to small communities and revise the current subsidy program.

The most important and controversial features of the measure - pricing and routes - are being saved for last.

On Thursday, Sen. Cannon blasted the lobbying by most members of the airline industry against the measure. After listing those in favor of the measure including the current and the last administration, the CAB itself under the current chairman and his most recent predecessor, business and consumer groups, as well as Pan American World Airways, Frontier Airlines, and Hughes Airwest, Cannon asked, "now who's against it?

"The very narrow private interests involved in the industry are against it: about 18 scheduled airlines and three or four labor unions are opposing it," he said. "They are spending thousands and perhaps hundreds of thousands of dollars to defeat this bill . . . They want to continue to operate like a closed fraternity, protected by an outdated statute and a paternal regulatory agency."

The cariers opposed to the bill have contended that passage of the measure could lead to airline bankruptcies, increased concentration, loss of service to small communities, and higher fares, not lower rates as the proponents of the measure contend are possible with more competition.

Based in large part on what they've been told by airlines serving their areas, may legislators are wary of the measure: the concerns were obvious at the open committee markup sessions.

In two letters to the committee this week, the CAB reiterated its support for change. "We believe that the present regulatory system - is basically unsatisfactory," Kahn wrote. Although he noted the board has some reservations about what they view as "the inflexibility of some of the time limits set for actions by board," Kahn noted they "not only can live with the bill if it were passed unchanged in its present form - we would regard the new law as a major imporvement over the present situation."