Jeri Jackson had seen television reports that heightened airport security prompted by concern about terrorism could cause exasperating delays during the busy travel week before Christmas. So she arrived early for her flight yesterday to Kansas City, Mo., from Reagan National Airport--six hours early.

What she found was a terminal free of crowds, short lines at the security checkpoints and practically no delays at all. "We were kind of surprised," admitted Jackson, homeward bound after a two-week business meeting.

Her experience was shared by travelers yesterday at all three Washington area airports, who encountered little sign of a security crackdown despite the announcement by law enforcement agencies Tuesday that they would be redoubling their efforts everywhere.

"I didn't notice anything special. It doesn't seem like a terribly busy day," said Eileen Essaye, of Northwest Washington, who was traveling with her husband, Tony, to Charlotte for the holiday.

Officials at both Baltimore-Washington International Airport and the Metropolitan Washington Airports Authority, which runs National and Dulles International Airport, reported that passengers would detect little difference because security is always high at their terminals because of their proximity to the nation's capital.

"Everybody involved in the airport is aware that the system already in place should be followed," said authority spokeswoman Tara Hamilton. She said that National and Dulles were maintaining the same security measures, such as patrols by dogs, that first were adopted two years ago.

BWI spokesman John White said, "It's business as usual here."

And with the heaviest volumes of this week not expected until today, crowds were thin. Unlike on the days immediately before Thanksgiving, travel during the week before Christmas is spread out, building to a peak today before dropping off until after the holiday.

Business at airport ticket counters yesterday was steady but hardly crushing. Tables at Legal Sea Foods, T.G.I. Friday's and other restaurants at National remained empty even at lunchtime, and a string trio hired to play Christmas music found an audience only in a trickle of travelers in an otherwise silent terminal.

"It's really pretty slow right now. We happen to be playing for whoever is here to hear us," said guitarist Gerry Kunkel, of Darnestown.

At Dulles, Stephen LaValle, of St. Louis, said he had not observed anything unusual during his trip to the Washington area. "There's less of a crowd than I'm used to," LaValle said, his 1-year-old son, Ethan, chuckling behind him. "And the airport is pretty empty; all you have to do is look around."

Arriving at Dulles, Janice Selman Taylor, of Trinidad, said her experience with customs and immigrations officials was uneventful. "This experience was quite easy, no hassle," Taylor said. She said that there were several dogs sniffing luggage but that she welcomed the security. "I'm quite satisfied with how I was treated."

Mike Casciaro, of Alexandria, arrived more than an hour early to pick up his mother-in-law because he was expecting tight security and long lines. His son, Sebastian, 9, held flowers and an American flag in anticipation of meeting the plane from Amsterdam.

"We left early because we thought they'd be searching through trunks or searching bags when we got to the airport," said Casciaro, a Pentagon worker who said recent reports of people trying to smuggle bombs into the country concerned him. "But it was just like normal. It bothered me a bit because I was thinking they would be cracking down."

Likewise, at National, Kathie Walch, of Fairfax City, said she was taken aback no one asked to examine a sealed box she was lugging onto a flight to West Palm Beach. "Nobody's done anything different," she said.

CAPTION: Anticipating delays, Jeri Jackson, right, arrived six hours early for her flight. She waited with another traveler, Myron Reinke, at National, which reported no delays yesterday.

CAPTION: Reagan National Airport offered music by Pam Ferguson, left, Tom Baldwin, center, and Gerry Kunkel, who said traffic was "pretty slow."