The only people more confused than today's air traffic controllers are today's airline passengers - especially if they want cheap tickets.

During the first 10 years of airline deregulation, airfares fluctuated wildly. Initially ticket prices declined, but in many cases they are now higher than their pre-1979 levels.To make matters worse, special deals and customer incentives such as supersaver and frequent-flier programs have left even experienced travelers confused when seeking the cheapest way to fly. Passengers often pay significantly different fares for the same seats on the same planes.

This week we offer a handy guide to current airfare terminology and a variety of tips on cutting your air travel costs.

TYPES OF ROUTES

Non-stop vs. direct. A "non-stop" flight travels straight to your destination without stopping. A "direct" flight means only that you do not leave the plane when visiting one or more other airports on the way to your final destination.

Connecting. Here you will have the joy of changing planes, layovers and maybe tracking down your luggage in a strange airport.

Understandably, direct and connecting flights are usually cheaper than non-stops. However, be sure to investigate alternate prices and routes to see if the hassle is really worth it.

FREQUENT-FLIER PROGRAMS

Frequent-flier deals, also known as Mileage Plus programs, allow you to accumulate bonus credits for every mile you fly with the same airline. When you reach a certain total, you receive credit good for seat upgrades, free tickets or discounts on future travel.

For example, United Airlines will give you a free round-trip coach ticket to anywhere in the continental U.S. after accumulating 20,000 miles. After 40,000 miles, you will get two round-trip coach international tickets or one round-trip first-class international ticket.

You also can get airline mileage points for using specified credit cards, hotels and rental car companies.

BUDGET FLIGHTS

Created with the bargain traveler in mind, budget flights often carry penalties for cancellations or schedule changes. If there's a chance your trip may be canceled, you might save money with a more expensive flight.

Maximum-saver fares are non-refundable tickets, which is why they are so inexpensive. In some cases, you may be able to change the return date for the payment of a small service fee.

Continental and American Airlines currently offer a break for people stuck with Maxi-saver tickets they can't use. If you need to make a change on the return portion of the ticket, you can do so for $75. However, there are stipulations - there must be seats available on the return flight, and you have to make advance reservations.

Promotions offer periodic savings to boost sales. For example, recent terrorist attacks have persuaded many overseas travelers to stay at home, so some carriers now offer great deals to Europe. Pan Am currently has a limited "Summer Sale" to Europe, with midweek prices fom New York to London at only $298 round-trip.

Continental Airlines now has a summer sale on children's fares. Adults purchasing maxi-saver tickets for a Tuesday or Wednesday domestic flight may take a child along for only $1. On other days of the week, children's fares are half-priced. The tickets must be purchased by May 26 and used June 1 through Sept. 10th.

BEST TIMES TO SAVE

When you fly and when you buy your ticket can result in big savings.

Off-peak rates. By altering your departure time a few days or even a few hours, you may qualify for lower fares. The cheapest flights usually are midweek (although you may be required to stay over a Saturday), early morning or late night.

Shoulder season. Rates vary depending on your destination, but waiting to fly until the shoulder season (the periods on either side of summer and the holidays) can save big bucks. Rates usually go down on September 15, up again around Christmas, back down in February and then reach their peak during the summer.

Standby. Flying standby is perhaps the cheapest way to go - ideal for students and anyone on a limited budget with time to kill. You must check in at the airport well before flight time and you will fly only if space is available. It may be like playing the lottery, because no one knows how many seats will be available due to no-shows.

Winners are determined on a first-come/

first-served basis. Early birds often take wing for morning flights by checking in at 12:01 a.m. Flying standby can save hundreds of dollars or more, but you better bring a book.

All of these special flights and fares vary widely depending on your destination and what airline you eventually choose.