Good news for vacation travelers is that air fares are being cut to the bone. New Super Saver fares - discounts of 30 to 60 percent on both domestic and international flights - are being announced every day.

Two weeks ago, for example, Lufthansa set a $393 round-trip fare from New York to Frankfurt ($50 more from Chicago), a 40 percent cut from its regular tourist price. Round-trip budget fare on the Portuguese airline, TAP, is $343 New York to Lisbon, a discount of more than 50 percent.

In the United States, new Super Saver fares promise discounts in the area of 30 to 45 percent between most major cities. Different airlines apply different names to their lowest fares, but all the major carriers have them. Prices are generally a little lower if you can fly midweek rather than weekends.

Laker Airlines, which started this fabulous price war, is doing good business on its New York to London flight, $250 round trip. There are no reservations - you just go out to the airport and get in line. Starting April route for a total of 500 seats a day - 1, there will be a second 704 on the enough, Laker thinks, to accommodate everyone.

"Freddie Laker is one of the few innovators I know who is actually making money," Hal Gieseking, managing editor of The Travel Advisor, a newsletter on budget travel (40 Beechdale Rd., Dobbs Ferry, N.Y. 10522), told my associate, Anne Colomosca. "Usually it's the second or third guy who cleans up after the innovator goes broke."

Other international airlines compete with Laker on the London route. Pan Am, for example, charges $236 compared with $635 for its regular coach fare. But you can't pick the day to travel. you tell Pan Am which week you want to leave, and shortly before the flight Pan Am gives you a day and time.

The terms and condition of budget fares vary from airline to airline. Some give you unlimited days at your destination; others set the trip at seven to 30 or 45 days. Some require that the ticket be bought a certain number of days in advance, others don't. Some insist on round trips, others let you travel one way. Your (or your travel agent) should call the various airlines, asking wht terms accompany their lowest fares.

Eastern Airlines has a fare that Gieseking calls a "Walter Mitty fantasy." For $299 you can fly anywhere in the country, for seven to 21 days, if you reserve in advance. you have unlimited mileage, and can backtrack if you want. This fare includes all of Eastern's domestic stops, plus Mexico and San Juan. One hitch: It's a pair fare. You get it only if you're traveling with another adult. Your companion pays the same amount.

These low fares may be bad news for operators of Advanced Booking Charters, which are booked through travel agents. ABC fares still tend to be the lowest around, but they've lost their decisive edge.

There have been a lot of complaints about air charters. The biggest problems: Departures delayed by many hours; cancellations; problems with refunds; and - on charters that include hotels - poorer accommodations than expected. Some hotels overbook, then shunt cut-price charter people off to lesser hotels at the last minute. Also, some charter operators don't deliver all th extras promised in the brochures.

On the other hand, plenty of charters come off just fine. For those with little money, they're still the best value around. "It's a trade-off," says Gieseking. "Money versus convenience." For a good list of the hundreds of charters available this season, write for Jens Jurgen's 1978 Charter Flight Directory and Guide to Other Air Travel Bargains, $4.95 from Travel Information Bureau, P.O. Box 105, Kings Park, N.Y. 11754.

Warning to European travelers: The decline of the dollar against many European currencies has made accommodations awfully expensive. You'll get better value in Mexico and points south, where the dollar has kept up its value.