Looking at a Six-Hour Flight Delay? Relax. Join the Club : Airports: Non-members are permitted to use some airline membership lounges for a per-day or other short-term fee.

Hundreds of thousands of this county’s most frequent fliers swear by them, fax from them, schmooze and snooze in them. But for most vacation travelers, an airline membership lounge still seems a not-quite-justifiable luxury. After all, the dues run around $150 a year for an individual, the expense is not tax deductible, and generally, you’re only welcome if you have a flight on that airline that day.

But what about those one, two or three days a year when you find yourself facing four or five or six hours in an airport, waiting for an awkward connection? That could be the time to take advantage of a little-known wrinkle in the rules of many lounges: Three U.S. airlines are now quietly offering short-term memberships in their private airport lounges--sometimes for one day, sometimes for one month, usually for $25 or $30.

This came in handy for me last month, when I found myself with seven hours to kill in the Miami airport, awaiting a connection to South America.

Since I happened to be flying American Airlines that day, I sought out the American Admirals Club (to which I have never belonged). There, I handed over $25 for a day’s membership, and settled in.

My baggage could wait in the cloakroom. I could receive a couple of faxes (which cost extra), make a few phone calls from a comfortable chair, watch television, read a magazine, sip free coffee or tea. And shortly before departure time, I was able to have the desk agent check seating for my next flight and move me to an otherwise empty aisle.

All in all, I’m not sure I’ve ever spent $25 more wisely in an airport. Here are the three airlines that make such arrangements possible:

American. Admirals Club. The carrier maintains 29 clubs in the United States and another 15 around the world. A traditional membership runs $175 yearly, plus a $100 initiation fee. Under the carrier’s day-pass program, which a representative said was “a few years old,” a non-member can buy a day’s access to the clubs for $25.

Continental. Presidents Club. A one-month membership runs $30, and can be bought on the spot at any club. There are 15 clubs in U.S. airports, one in London (Gatwick) and one in Paris (Orly). Traditional memberships run $200 for the first year, $100 for each following year.

United. Red Carpet Club. Since January, most or all of the carrier’s 22 U.S. club rooms have been offering one-day passes for $25. (Red Carpet Club representatives weren’t certain if every site was participating; travelers can check in advance by getting individual club phone numbers from the central Red Carpet Club office at 602-881-0500.) Traditional memberships run $175 yearly, plus a $100 initiation fee.

All three carriers permit club members to bring in immediate family members (including children) or two unrelated guests at no extra cost. Unfortunately, this offer doesn’t seem to carry the competitive force of, say, a fare sale, and many airlines have so far chosen not to follow.

Two of the non-participants are Delta (which makes its 39 Crown Rooms in North America available only to those who pay $150 per year) and Northwest (which open its 24 World Club rooms worldwide only to those who pay $175 yearly and a $50 initiation). Both of those clubs offer free alcoholic beverages--a perk that might not be prudent to offer anyone willing to pay for a day’s worth of privileges. (Other U.S. carriers exclude alcoholic beverages from their list of free perks.)

Among the other carriers that don’t offer short-term club memberships: USAir opens its 26 USAir Clubs in 20 U.S. cities only to traditional members, who pay $200 for the first year and $150 each for succeeding years. And Trans World Airlines (TWA) opens its 23 Ambassador Clubs in the United States and Europe only to members paying $150 for their first year and $125 for succeeding years. Southwest has no membership club.

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Airline membership lounges date to 1939, when American opened one at LaGuardia Airport in New York. Most offer discounts for spouses or multiyear memberships, and many accept mileage-program credits in place of cash payments. Hours vary widely, but most facilities offer sofas, armchairs, credit-card phones, faxes, photocopiers, televisions, magazines, a bar, and free coffee and tea. Some offer personal computers, and some include free soft drinks. Many have added ATMs.

For a fee, many make private conference rooms available. The American Admirals Club at Chicago’s O’Hare International Airport, for instance, rents out conference rooms for up to 12 persons at rates of up to $400 per day, or $60 per hour.

Most users of airline lounges are business people--in fact, job interviews are relatively common in those conference rooms--but use among leisure travelers has been increasing. (Statistics on the subject are hard to come by, however, because some airlines have decided to keep their lounge membership figures secret.)

The good news for those who would rather travel in comfort than in style is that as vacationers have increased their use of club lounges, dress codes in the lounges have relaxed. As a tieless traveler in jeans, I have never been challenged.