Residents seeking to flee Houston by air before Hurricane Rita roars into town are finding that only costly last-minute seats are still available.

Continental Airlines on its Web site yesterday was offering coach seats one way from Houston to Dulles International Airport for as much as $1,937. Searches of the travel Web sites SideStep and Orbitz turned up one-way and round-trip flights between Houston and the Washington area on various carriers from $300 to $624.

Airlines set aside only a certain number of cheap seats on each flight, and passengers rushing out of town have already gobbled them up. Many flights are sold out. Any last-minute tickets typically cost hundreds of dollars more than those bought a week or two in advance. One last-minute, round-trip fare on Continental, Houston's dominant carrier, between Houston and Washington was $516. If purchased two weeks ago, tickets for the flight cost $228.

Adding to frustrations of travelers yesterday were long security lines at Houston's Bush Intercontinental Airport. Some reports said a number of security screeners working for the Transportation Security Administration didn't show up for work. The TSA said it plans to fly 155 screeners from other cities to help with evacuation at Intercontinental and Hobby airports, said spokesman Darrin Kayser.

American Airlines, the world's largest carrier, said yesterday it was replacing four smaller, narrow-bodied planes with larger aircraft, two Boeing 777s and two Boeing 767s. The change will add 360 seats out of Houston's Intercontinental Airport. Travel experts say passengers should not expect those seats to be discounted as a goodwill gesture.

"Airlines are not a social service industry," said Terry Trippler, an analyst with "Everyone expects the airlines to take a financial hit then criticizes them when they don't make money."

The airline industry is struggling through its worst financial crisis in history, with four major airlines -- United, US Airways, Delta and Northwest -- operating under bankruptcy court protection. Airline experts say it is unreasonable to expect the carriers to offer special fares as they battle to survive steep competition and soaring fuel prices.

Last-minute fares between Houston's Intercontinental Airport and Washington's Reagan National Airport were about $5 more than they were a month ago, largely because of a fuel surcharge put in place following Hurricane Katrina.

While airlines don't often lower their prices during catastrophes, most do allow passengers to change their existing tickets without paying a $50 to $100 change fee.

Airlines and airports aren't the only industries bracing for the hurricane. Some of the nation's largest hotel chains say many rooms are booked for miles outside of the city. Many rooms were already occupied by New Orleans evacuees and relief workers.

Hilton Hospitality Inc. is urging travelers to call its properties directly to check on available rooms. The hotel chain offered discounts for Katrina evacuees: rooms for about $19 a night, depending on the location. Hilton spokeswoman Katy Shephard said a decision has not been made about discounts for Rita evacuees.

Thousands of people at Bush Intercontinental Airport wait to evacuate Houston. Security lines may have been worsened by screener no-shows. The Transportation Security Administration planned to fly in more screeners.Srinivosa Dhulipalla checks in at Hobby Airport. American Airlines used larger aircraft and AirTran Airways increased service out of the city.