The catalog was impressively glossy; the timing of its arrival couldn't have been worse.

The mail last week brought American Airlines' European vacation-packages brochure, but most eyes are on the Persian Gulf, not the Continent.Not that American Airlines officials needed reminding. Their trans-Atlantic jetliners were "flying well under half-full, below normal even for this time of year," spokesman Tim Smith said.

The start of the war Jan. 16 proved a startling turnaround, he added. Up to that day, "The percentage of (trans-Atlantic) cancellations was well under 1 percent" of total reservations. Then, "We saw a dramatic drop-off in load level" to and from Europe.

The conflict has scrambled travel plans, erased many penalties for airline-ticket cancellations or changes, and also is likely to hasten the decline of two troubled U.S. airlines.

Even before the bombardments began, the effect of the months-long Gulf crisis on travel was a complex equation. Winter is a traditionally slack period for tourism abroad, and the Mideast is only minimally important as a tourism destination anyway. Airline traffic has been "soft" for more than a year; the recession and increases in fuel prices hurt the industry, too.

One thing is certain - whenever the war ends, the high-profile airline industry will look different. Once Iraq invaded Kuwait in early August, vacation travel to the Mideast dropped precipitously.

"When this (invasion and the U.S.-led response) first happened, we had a lot of bookings. Then we had perhaps 50-60 percent cancellations in September and October," said Eileen Lowe Hart, marketing director for Isram Travel, a New York firm that claims to be America's busiest packager of tours to Israel.

"Normally, this is off-season (for tourism) in Israel. However, it is the season for Egypt, and Egypt is down tremendously, probably about 70 percent," Ms. Hart said.

Isram moves between 10,000 and 20,000 tourists yearly to Israel, Egypt, Turkey and Greece. "It's been a very dismal winter for us," she added.

Even to the British Isles, relatively distant from the Persian Gulf, business was off. A spokesman for Trafalgar Tours, a major wholesaler of package tours to the United Kingdom, reported reservations were down about 10 percent this winter compared to 1989 business.

Then, with the start of hostilities, not only vacationers but many major corporations began canceling overseas travel for an indefinite period.

Although major domestic airlines such as American, Delta, United and USAir fly to European destinations, they don't serve the Persian Gulf. Two U.S. carriers that were once leaders in trans-Atlantic travel, Pan American and TWA, do fly to the Mideast but have cut back service dramatically. Talk within the industry is that the two lines will never resume those levels of service.

Pan Am this month suspended flights to Tel Aviv, Riyadh, Athens, Istanbul, Ankara and Karachi, Pakistan. The airline, which has filed for protection from its creditors under Chapter 11 bankruptcy proceedings, last October agreed to sell its prestigious and profitable routes to London to United Airlines. Before the deal was closed, Delta offered to buy the routes.

TWA also announced it was suspending service to four cities in the region. Then, last week, the airline announced it was nearly halving its 40 trans-Atlantic flights and laying off 2,500 employees.

Coinciding with the early days of the war, Eastern Airlines finally closed down, after 23 months of operation under bankruptcy court protection.

Foreign carriers have also reduced their service to the Mideast. For instance, British Airways stopped flying to Tel Aviv and Dhahran; Lufthansa halted service to Tel Aviv, Damascus, Amman, Bahrain, Riyadh, Luxor and Cairo.

Both of those airlines "altered flight patterns so that we don't overfly the 'hot areas' " near the gulf, as British Air spokeswoman Margaret Vodopia put it.

And Lufthansa added surcharges of up to $250 for tickets on Mideast flights, to cover "tremendously increased" insurance premiums for the aircraft and passengers.

Passengers who do choose to fly after the end of this month are likely to notice slightly higher ticket prices, due to fuel-price surcharges and the end of discounted fares that were slashed to meet Eastern's cheap tickets.Easing, tighteningthe rules

As a result of the crisis, airlines are relaxing the strict, no-refund rules that had encumbered their most-heavily discounted tickets.

The accommodations generally allow travelers already overseas to change the return-departure date without penalty, and for those who do not want to use their tickets now, vouchers will be issued to apply against the cost of tickets at a later date.

Airlines including American, Continental, Delta and United are offering cash refunds or rebookings without penalty. The airlines' spokesmen emphasize these dispensations are being applied on a case-by-case basis.

All airlines and airports are increasing security precautions, but spokesmen refuse to disclose most specifics, lest they tip terrorists on how to circumvent the plans.

Passengers should call to find out how early before departure they should report to the airport. The added time for security checks will range from one hour to 2 1/2 hours.

Other noticeable changes at the airports, many based on Federal Aviation Administration recommendations:

- Curbside check-in has been eliminated, so that unaccompanied luggage can't be checked aboard a plane.

- Many airports are removing coin-operated storage lockers, to lessen the chance of a bomb being left.

- Unclaimed luggage in the baggage area will be removed, once police have determined a sufficient time has passed for passengers to retrieve their bags.

- Only ticketed passengers are allowed in areas leading to the departure gates.

- Passengers will likely have to remove the batteries from portable computers and cassette players. Authorities say the bomb that exploded aboard the Pan Am jet over Lockerbie, Scotland, in 1989 was concealed in a small, battery-powered radio.

Searches of carry-on baggage are based on a passenger profile nobody wants to talk about. But MacAlester confirmed that profile criteria include passengers traveling alone and passengers traveling on a one-way ticket.

Many of these measures were recommended to the FAA by a presidential panel following the Pan Am jet explosion. Although the new searches and precautions have raised the apprehension of some travelers and have aggravated others, most Americans have no appreciation for security until they've walk through airport terminals in Europe or the Mideast.

Even last October, months before the Jan. 15 deadline, police or soldiers were carrying automatic weapons and patrolling Amsterdam and Frankfurt airports, in groups of two or three. Armored personnel carriers roll along the runways at Frankfurt. In Amsterdam, a guard with an automatic rifle stood among the Atlanta-bound passengers in the departure lounge, while service-truck drivers were frisked before they were allowed to tend to a Delta jet.