President Reagan yesterday announced his plans to nominate a Republican broadcasting executive to head the Civil Aeronautics Board.

Clinton Dan McKinnon, a San Diego businessman who ran unsuccessfully for Congress in 1980, is slated to become chairman of the CAB some time this fall after the current head, Marvin S. Cohen, steps down

Cohen, a Democrat, last week announced his intention to resign on Sept. 15 -- four years before his term is due to expire.

McKinnon, 47, owns two radio stations and three television stations in California and Texas and the House of Hits Music Publishing firm.

Although McKinnon acknowledged that he had little background in aviation beyond a sports interest in aerobatic flying, he said yesterday he thinks he could use his business knowledge to make the CAB "operate efficiently."

In a telephone interview, he also said no change in the CAB's move to deregulate the airline industry is expected.

The CAB is due by law to go out of business by the end of 1984. However, it may go out of existence even sooner -- perhaps as early as October 1982. The Reagan administration wants to speed up its elimination on the grounds that, since deregulation of the airlines, the CAB no longer is needed to monitor closely the business operations of the nation's carriers.

Closing up the CAB is "the exciting part of the whole job," McKinnon said. "It's a challenge, and I like challenges."