A situation reminiscent of the Perils of Pauline at the Civil Aeronautics Board last week threatened to give federal economic regulation yet another black eye.

Would 1,6000 Pan American World Airways customers show up at airports in New York and London, with $256 round trip tickets, only to told that because of a CAB fare decision they needed another $369?

The cab couldn't let that happen. For one thing, the agency had been slow to act on Pan Amerproposal for the fares. While some people at the CAB saw a touch of arrogance in the way Pan Am sought to exempt itself from the fare decision, the agency managed to find a solution the the dilemma.

With a little help from our friends in Britian, who agreed to permit low-fare North Atlantic service to begin earlier planned Pan Am was permitted to offer a new $280 budget fare for those with $256 tickets. So consumers only had to come up with an extra $24.

Only a happy start could be permitted the new era of cheaper New York-London air fares clearly a major chapter in the development of international aviation.

Overshadowed by the North Atlantic fares, however was anothe r CAB decision with potentially broader implication for this country's many regulated industries.

By a vote of 5-0 the CAB agreed that domestic airline fares could be based in part, on projected costs.

Although there have been attempts in recent years to include business projected costs in rate decisions by some state public utilities commissions, federal agencies and most state bodies generallyhave followed a traditional policy of refusing to consider the future.

Typically, in a state regulatory case involving higher telephone or electricity rates, commissions pinpoint a past "test" period by which measure revenues, expenses and profits of a company or industrY. Future rates are based on the past preformance record.

At the federal level, economic regulation has followed a similar pattern. Industries seek higher prices for their services and they cite material costs, new labor contracts and general inflation as factors pushing up expenses.

In times price stability, it works will. But an era of inflation does damage to almost every insititution regulation not excepted. By the time new price based on past experience take effect, profits supposedly permitted by inflation. And that touches off another round of rate increase requests.

Partly because of his experience at New York's Public Service Commission, which experimented with rates based on projected costs, CAB chairman Alred E. Kahn helped convince his colleagues to try a new approach to airline fares at least for a while.

U. S. airlines have been t the CAB five times this year, seeking relatively small increases each time. This has created a great deal of confusion for the public, with fare boosts taking effect in February, then July, August and September.

Kahn said he was able to win support for the idea of permitting airlines to base fares on some projected expenses by framing it in terms of "a tradeoff on frequency."

The CAB decisdionbfor which a formal order has not been printed allows fares to be increased on the basis of costs projected up to three months beyond the effective date.

Kahn said a goal is to "gradually work our way into a transition" to two rate increase proposals a year. Trans World Airlines was a principal advocate of the plan, which will be watched closely by other industries.

FOR EXAMPLE - A Spokesman for th railroad industry, Richard E. Briggs of the Association of American Railroads called the CAB plan "extremely progressive." The rail industry will file a 5 per cent general freight rate increase Monday with the Interstate Commerce Commission, to become effective Nov. 30.

Kahn said he was able to win support for the idea of permitting airlines to base fares on some projected expenses by framing it in terms of "a tradeoff on frequency."

The CAB decidion for which a formal order has not printed, allows fares to be increased on the basis of costs projected up to there months beyond the effective date.

Kahn said a goal is to "gradually work our way into a transition" to two rate increase proposals a year. Trans World Airlines was a principal advocate of the plan which will be watched closely by other industry.

AT THE AGENCIES - Commodity Futures Trading Commision chairman william T. Bagley writes, in next Monday's edition of Federal Times, about a "reign of undue process" at federal agencies, which he notes perform not only the role of rule maker but investigator, grand jury and judge. The solution: A separate court of regulatory affairs.

The ICC has a new managing director, Pierce A. Quinlan, former administrator of employment development at the Labor Department . . . Federal Trade Commisison votes to bar contacts with interested parties after beginning any trade regulation proceeding on 3-2 vote with Calvin Collier and Elizabeth Dole in the minority . . . General Accounting Office begins a study of broadcasting regulation . . . Jerome Nelson of the CAB to become general counsel for the Nuclear Regualtory Commission, says Energy Daily . . . Environmental Protection Agency considers rules on permissible garbage truck noise . .. also, bulldozers.