At the captain's discretion, passengers can once again have blankets and other items on their laps or move about the cabin during the tail end of flight. Restrictions on in-flight entertainment systems that show the plane's path were also lifted.
The airline officials spoke on condition of anonymity because federal safety officials had not publicly announced the changes.
A spokeswoman for the Transportation Security Administration said the agency was "continually reviewing and updating" security measures. She declined to offer details.
Tougher airline security measures were imposed Friday after a man flying from Nigeria to Amsterdam then to the U.S. on a Northwest Airlines flight tried to ignite an explosive as the plane prepared to land in Detroit. On Sunday, police met another Amsterdam-to-Detroit flight after the crew reported a "verbally disruptive passenger." A law enforcement official said the man posed no security risk to the plane.
The procedures, including more extensive pat-downs of passengers and examination of baggage, led to longer lines at many airports, and security personnel were extra diligent.
Travelers on incoming international flights said that during the final hour, attendants removed blankets, banned opening overhead bins, and told passengers to stay in their seats with their hands in plain sight.
Before a Continental Airlines flight from Cancun, Mexico, to Newark, N.J., even babies were frisked. Once in the air, when flight attendants announced that the toilets would soon be off-limits, passengers lined up 10-deep for a last chance to go. One attendant threatened to confiscate Christmas cards that a passenger held in her lap to write on them.
In Philadelphia, sisters Leslie and Lilliam Bernal said security was much tighter as they returned from a wedding in the Dominican Republic than it had been in September, when they made the same trip.
Leslie, 26, of Keasby, N.J., said security screeners in Santo Domingo asked her to lift her long hair so they could look at her back.
"I don't mind at all," she said. "I'd rather them do what they have to do."
Authorities introduced a second layer of security at Pearson International Airport in Toronto. On Monday morning, every U.S.-bound passenger was subjected to a pat down and their luggage was inspected by hand. It took about three hours for travelers to get through the checks.
Before an Air Canada flight left Toronto for New York's LaGuardia Airport, the crew told passengers to stay in their seats for the entire one-hour flight and stop using electronic devices, even iPods or their own headphones. The crew said passengers couldn't get into their personal belongings because of the "enhanced security procedures."
At Hartsfield-Jackson Atlanta International Airport, television screens were tuned to the Atlanta Falcons football game, and some passengers were only faintly aware of Friday's incident in Detroit.
Jeff Fox, of Alpharetta, Ga., who was returning with his family from Ft. Lauderdale, Fla. after a weeklong cruise, said he will tolerate new restrictions if officials think they will keep passengers safer.
"I'm one of those who trusts that they're trying to do the right thing, even if it is a pain," he said.
The incident Friday, however, continued to raise questions about security, said Jack Riepe, a spokesman for the Association of Corporate Travel Executives.
Riepe said corporate travel managers want to know how Friday's suspect reached Detroit even though he was on a watch list maintained by counterterrorism experts. A government official said the suspect's father raised concerns about him to U.S. officials several weeks ago, but the father's information about his son's possible ties to fundamentalist Islamic groups was too vague to act upon.
U.S. airlines appealed to federal officials to make restrictions effective but palatable to passengers.
They remembered that passengers accepted tough new security measures immediately after the 2001 terror attacks, which grounded all flights for several days, but that support for the restrictions waned.
AP writers Shannon McCaffrey in Atlanta, Karen Hawkins in Chicago, Kathy Matheson in Philadelphia, Matt Lee in Washington, Dan Strumpf in New York, John Heilprin in Toronto and Sheila Norman-Culp in London contributed to this report. Koenig reported from Dallas.