Chantilly, Va. ? On the first day the government took responsibility for airport security, some passengers noticed extra vigilance and felt reassured by the change. Federal officials pledged on Sunday to protect travelers and treat them with courtesy.

The second major deadline in the new airline security law passed as smoothly as the first, when airlines last month began inspecting checked baggage for explosives. A new federal agency now oversees aviation security rather than the airline industry and Federal Aviation Administration.

“As of now, we will make sure we’re observing the screening and make sure it’s being done properly,” said John Magaw, undersecretary for transportation security, after arriving at Washington Dulles International Airport from Miami.

With the same screeners staffing security checkpoints, and even airline officials helping to oversee the operations, officials said passengers at first will not see much of a difference.

“It’s really a change in the reporting structure,” Frontier Airlines spokeswoman Tracy Kelly said. “It’s still the same screeners checking bags.”

Sunday’s deadline was the first step in a nine-month transition from private security companies to a better-trained, higher-paid federal work force to screen passengers and baggage.

What passengers should notice are the chairs they can use when they are asked to remove their shoes to be checked for explosives. In addition, travelers inspected with handheld wands will have their valuables in front of them.

“I hope that they’ll notice a slight difference in the courtesy,” Magaw said. “Hopefully, they won’t notice anything much different than that.”

Some arriving passengers at Dulles, where a plane was hijacked Sept. 11 and crashed into the Pentagon, said security was tighter than they had seen since the attacks.

“We commented on it,” said Robin Cloninger of Morristown, N.J., arriving from Fort Lauderdale, Fla., with two classmates from Loyola College in Baltimore. “A lot more people were getting their bags searched, taken off the line.”

A passenger at Chicago’s O’Hare Airport, Cheryl Jones said screeners stopped to examine each X-ray image of carryon luggage rather than just speeding the bags through the machine.

“Usually you’re running to get your bag coming out the other end,” Jones said before her flight to Jacksonville, Fla.

But Mike Adams, a ticket agent for AirTran Airways at Atlanta’s Hartsfield International Airport, said he did not see any changes.

“It’s all internal,” Adams said. “Security’s security, so I don’t think you’ll see the government do anything different.”

As he sat on a suitcase in the Dulles baggage claim area and waited for his ride, Mark Bontrager of Springfield, Va., said it did not matter who was supervising security “as long as you hold them to the standards.” Looking up from his book, he said, “I don’t think it can ever be foolproof, but I think it’s better. Taking the time to do the job right is what’s most important.”

Likewise, Gordon Sommers, waiting at New York’s Kennedy Airport for a return flight to Kingston, Jamaica, said he just wanted the security screening done well.

“I don’t much care whether it’s Civil Service or contracted service as long as it’s effective,” Sommers said.

The change provided reassurance to Scott Landis of South Berwick, Maine.

“I’d rather have the federal government handle it than the airlines,” said Landis, flying to Florida with his family from Boston’s Logan Airport, where the two planes that smashed into the World Trade Center took off from on Sept. 11.

“It’s the appropriate role for the government to play. The airlines have been shown to be lax in the past.”

Renier Kraakman of Cambridge, Mass., escorting his 11-year-old daughter to her flight at Logan, didn’t see any difference.

“It’s just for show,” he said. “But if it makes people feel good it’s worthwhile.”

Kendra Lynn of Tulsa, Okla., said it did not take longer for her to pass through security Sunday at Dallas-Fort Worth Airport. But she said she would not complain even if federal oversight meant more thorough checks. “We’re thrilled with any kind of excess screening,” she said.

Security workers said they were aware of the federal supervision.

“I’m nervous,” said Girish Vakil, a security worker for Argenbright Security Inc. at Dallas-Forth Worth. He added: “I’m a good worker, never failed a test.”