Once again responding to the continuing increase in the cost of jet fuel, the Civil Aeronautics Board yesterday gave the nation's airlines permission to raise domestic air fares by up to 3.3 percent, effective Jan. 1.

The previous increase in the domestic fare ceiling -- of 3.7 percent -- took effect on Nov. 1 and had boosted allowable fares to a level 26 percent higher than they were at the beginning of 1979.

The CAB this year began readjusting the fare level every two months instead of every six in order to help the airlines cope with unpredictable but rapidly rising fuel costs.

The Jan. 1 increase is based on expectations that the price of fuel through Feb. 1 will average 80 cents a gallon; it was 52 cents in June and 67 cents in September and has become almost monthly an increasingly larger and larger share of each airline's overall expenses.

In another action, the CAB approved an unusual promotional "holiday pass" travel program proposed by Texas International Airlines. The program is unusual because traverlers may accumulate enough "passes" to travel free on the airline in the future and because airlines traditionally do not offer promotions during the normally heavily-booked holiday period.

The program is also designed to bring to the Texas-based airline -- which flies out of Baltimore-Washington International Airport -- passengers already holding tickets on other airlines.

Here is how it will work: Passengers holding already purchased tickets for airlines flying the same routes as Texas International will be issued "Peanuts Holiday Passes," if they use those tickets on Texas International instead.

The passes will be issued between Dec. 22 and Jan. 14 for the equivalent amount of the price of the tickets written on other airlines -- used on Texas International during that period. The passes will then be redeemable for transportation on Texas International between Jan. 15 and April 30, 1980. Passengers could accumulate enough passes to receive free flights during that time.

An airline spokesman explained that two adults and two children flying in the next few weeks between Washington and California on tickets totaling $1,841 roundtrip will be entitled to that amount of "passes" good for any regular coach travel later if tickets written on the other airlines' stock are used instead on Texas International.

Although advance bookings are higher this year than last, Texas International officials said yesterday they expect that as many as 150,000 empty seats are available between now and Jan. 14 for travelers holding tickets on other airlines. Texas International has 350 flights a day.