IF YOU Plan to clip this article about current air fares and refer to it later - don't. Any similarity between today's fares and tomorrow's is likely to be strictly coincidental.

Thanks to a Civil Aeronautics Board that is bent on encouraging low fares in the domestic market, an industry using every opportunity to show the public and Congress it can provide the public low fares under the existing regulatory scheme, a President who has made it clear that no international fare is too low for approval and the arrival on the scene of Freddie Laker, providing low-fare competition even among the members of one of the best-laid cartels, air fares are both lower and more fluid as we start 1978 than they were a year ago.

They are also generally a lot more complicated. Now, in addition to the old stand-by (Whoops!) promotional fares, we have fares called the Super Saver, the Super Coach, the Super No-Frills, the Simple Saver, the Liberty Fare, the Unlimited Mileage Fare, the Aero-Bus, the Hopscotch Fare, the Peanuts Fare. Waiting in the wings are the Super-Jackpot and the Home Free Fare. There are now special fares if you leave and return on the same day, leave on Saturday and come back Sunday morning, leave at night; special discounts if you are clergy, a senior citizen, in the military, wearing a green tie. . . ?

In international aviation, too, teh introduction of Freddir Laker's Skytrain no-reservations, low-fare service in September has caused other airlines to react with some low fares of their own. But unlike his relatively simple fare structure - $135 to London from New York, $103 back - a plethora of fares, with a nyraid of conditions, are now available; and they compare favorably to the $626 normal coach fare betweeb New York and London. In direct response to Laker, we find new "Budget," "Stand-by" and "Super-Apex" fares. Perhaps it is significant that British Airways' recent publication, Robert Morley's "Uncomplicated Guide to Transatlantic Fares," needs to be 16 pages long. Morley lists II fares available on BA from the United States to Britain, with the Rules that apply to each, not counting two kinds of charter fares, group fares and children's discounts.

In contrast, Alitalia has reponded to the competitive spur across the Atlantic by simplifying its fare structure and lowering its prices across the board for travel to Italy. It has reduced fares for regular-paying customers - not just travelers who can or want to plan their trips far enough in advance to take advantage of the various advance-purchase fares and are willing to stay a certain minimum of days and meet other requirements. Alitalia has reduced its first-class fare by about 25 per cent and normal economy fares between 13 and 18 per cent.

It also has eliminated several fares altogether - such as the advance purchase excursion fares (APEX) that many other carriers are making their "low-fare" alternative - and simplified its promotional fare structure, combining the 14-to-21 day and 22-to-45-day fares into one with a pricetag 17 to 35 per cent below the old ones. It also had combined the rwo winter group inclusive tour fares into one, with reductions ranging from 9 to 30 per cent.

Pan American World Airways, which competes with Alitalia, has matched its Italian competitors's fares generally but kept the whole range of fares.

The more complicated array of fares both domestically and internationally means more work for the traveler - or a chosen travel agent: but patience and perseverence may yeild substantial savings over regular fares and make a trip that was too expensive last year fall within the budget this year. Above all, check around and be sure to ask travel and reservations agents the question, "How can I get there most inexpensively?"

Among the major discount fares for domestic travel:

The Super Saver. A sdavings of up to 45 per cent over the regular coach fare between here and other East Coast cities on the one hand and the West on the other, depending on the day of flight, the city of origin and destination. You must purchase your ticket 30 days before departure and stay at your destination between seven and 45 days. Fares are least expensive if you travel Tuesday, Wednesday and Thursday. Savings of up to 40 per cent are available Monday and Friday, with savings of up to 35 per cent on Saturday and Sunday. As with other discount fares, there are a limited number of seats available at these fares.

Super Coach. Between Baltimore and Chicago, Trans World Airlines has begun a new service with a coach fares reduced 36 per cent from $76 to $49 one-way. Available on one daily flight each direction. No purchase or length of stay restrictions.

Super No-Frills offered by Eastern Air Lines and National Airlines and Aero-Bus by Delta Air Lines. For flights to Florida from New York. Though avaiable only from New York, travelers from Washington may want to investigate the possibility of going North to get South to take advantage of reductions of up to 50 per cent off coach fare. One-way Monday through Wednesday fare, $55; Thurday through Sunday, $75, compared to regular $109 fares. Regular Washington to Miami fare is $100.

Unlimited Mileage Fare. Eastern's. For between $302 and $323 each, two or more adults may travel between seven and 21 days to any cities on Eastern's route: United States, Mexico, Bermuda, Bahamas and the Caribbean, but excluding Canada. Reservations must be made and tickets paid for 14 days prior to departure. At least two stopovers in addition to the final destination are required. One adult may take two or more children under 12 (children's fare about $205 each).

Liberty Fare. Allegheny Airlines' unlimited travel plan: anywhere the carrier flies for one fare - seven days for $149, 14 days for for $169, 21 days for $189. leave before noon on weekdays or anytime on weekends, must buy Liberty Fare Exchange Order seven days in advance.

Unlimited Sunshine Fare. National's two-or-mpre system-wide fare for $323. Rules similar to Eastern's fare apply here.

Senior Saver. Allegheny's new stand-by fare for those 65 and over. Other airlines following. Under Allegheny plan, the senior citizen must make an application for a Senior Saver I.D.card, at a cost of $20 for two years of travel on available flights. The fare applies on a stand-by basis only. No reservations permitted, and certain holiday periods are exempted.

Saturday Flight Sale. Through March 19 Allegheny is offering a 50 per cent reduction from the regular coach fare on any round trip if the passenger leaves on saturday and returns the next day on a morning flight.

Other discounted domestic fares include the regular excursion "Freedom" and "Discover America" typr fares, with discounts ranging from 15 to 25 per cent, depending on season, with minimum and maximum stay requirements. Roundtrip tickets must be bought at least seven days prior to departure, and within a certain time after reservations are made.

There also are the night coach fares (20 per cent reduction from regular economy on designated flights generally leaving after 9 p.m.); weekend excursion fares (discounts vary, but its about 20 pe cent for those who leave after 7 p.m. Friday and come back before noon Monday; you can leave one weekend and come back another), and individual inclusive tour-baing fares (discounts of between 15 and 25 per cent, with minimum/maximum stay rules and a minimum lodging and land package required).

That is just a sampling of what's available on the scheduled airlines.

On the nation's charter airlines, a myriad of flights and package deals - with less strings than ever - also are available from tour operators and travel agents. In effort to make the services offered by the charter airlines more competitive with the scheduled carriers, the CAB recently reduced or eliminated many of the restrictions that had applied to the two principal forms of charters available to the public: the One-stop Inclusive Tour Charter (OTC), which includes sleeping accommodations and necessary surface transportation, and the Adance Booking Charter (ABC), air transportation only.

The board eliminated the advance-purchase requirements for OTCs altogether, and reduced the advance-purchase period for ABCs to 15 days; said it would allow 15 per cent of an ABC group to be signed up after the advance-purchase period, in addition to allowing 15 per cent of the passengers to be substituted up to the last minute; reduced the minimum ABC and OTC group size requirement from 40 to 20, and eliminated the minimum-stay requirements for both.

The board also had liberlized rules on charters bound for foreign places, but their effectiveness depends on whether the destination country accepts charters under the new rules. The U.S. government is seeking to gain approval for these new charter rules from as many countries as possible.

Among the major low fares available from the scheduled airlines to foreign places are: Skytrain. Operated only by Laker Airways between New York and London Tickets are sold on a first-come, first-served basis at Laker Center in Queens in New York, easily accessible from the airports and Manhattan, and from Gatwick Airport or a downtown train station in London, beginning at 4 a.m. each morning. So far 345 seats are available in each direction each day, but Laker had plans to increase service in April.

Budget Fares. Between New York and London, priced just a little higher than the Laker service ($256 round-trip), meals included (they are a slight additional cost on Laker). Book and pay for ticket at least 21 days prior to the week you want to travel. Traveler picks the week of travel - the airline picks the day and time and notifies the passenger at least a week before departure.No minimum or maximum stay requirements.

Standby Fares. Also between New York and London, price $256 round-trip. Stand-by after 4 a.m. on the day the traveler wants to leave. A certain maximum number of seats can ber available each week from Laker's competitors on the route - Pan Am, TWA, BA, Air India, El Al and Iran Air - but don't have to be if the airline fills seats with full-fare passengers.

Super-Apex. The fare carriers generally have been using it to respond to the lower New York-London fare for flights from other cities to major European and other destinations. Under the Super Apex ($290 from New York to London, $323 from Washington to London), a traveler pays for a ticket a certain period of time in advance of travel (it appears to vary depending on destination and airline) and stays between 14 and 45 days.