US Airways Group Inc., which carries 69 percent of air travelers here, said peak travel days will be Wednesday, Thursday, and Friday - and the same three days next week.
Planes will be full; 108 flights have been added Thursday and 32 flights on Friday across US Airways' network, including a second red-eye flight from Los Angeles to Philadelphia some days.
"We are also adding additional frequencies on certain days to destinations as diverse as Miami, Seattle, Aruba, and Nashville from Philadelphia," said US Airways spokesman Todd Lehmacher.
Air travel is expected to fall 9.7 percent nationally - 8.4 percent in the five-county Philadelphia area - from last year, accounting for about 6 percent of holiday travelers, the auto club AAA said.
Jet-fuel costs and capacity cuts in seats and flights are driving holiday airfares higher, with ticket prices expected to be up 21 percent compared with last year, AAA said.
"Air travel came back pretty strong last year, but now with fares increasing as much as they are, we think that's going to ease back air travel," said Shane Norton, director of travel and tourism analysis for IHS Global Insight Inc. Travel by air has declined every year since 2007, he said.
The trade group for the nation's airlines expects a "slight drop" in air travelers for the holidays: roughly 43 million, or about two million per day.
"Reasons for the drop are largely due to the economy, specifically energy prices, reduced personal disposable income, reduced household wealth," said Airlines for America spokeswoman Victoria Day.
Philadelphia airport officials urge travelers to give themselves plenty of time to go through security. Planes will be packed; passengers will cram more into carry-on bags to avoid checked-luggage fees, and not all bags will fit into overhead bins.
To ease the trip, they say:
Arrive two hours before a domestic flight, three hours before an international trip.
Have ID out, coats and shoes off, laptops out for screening. Passengers 12 and under may leave shoes on.
Put carry-on liquids in a clear plastic zip-top bag. Adhere to the 3-1-1-rule: 3-ounce or smaller containers for liquids, gels and aerosols, in a 1-quart clear bag, one per passenger.
Do not wrap gifts.
Contact staff writer Linda Loyd at 215-854-2831 or email@example.com.