Washington – Additional Layer of Restrictions Is Imposed on Airline Passengers

Washington – In the wake of the terrorism attempt Friday on a Northwest Airlines flight, federal officials on Saturday imposed a new layer of restrictions on travelers that could lengthen lines at airports and limit the ability of international passengers to move about an airplane.

Cpl. Frederick of the Wayne County Airport Police and his bomb-sniffing dog patrolled Saturday at the Detroit Metropolitan Airport in in Romulus, Mich.

Among other steps being imposed, passengers on international flights coming to the United States will apparently have to remain in their seats for the last hour of a flight without any personal items on their laps. Overseas passengers will be restricted to only one carry-on item aboard the plane, and domestic passengers will probably face longer security lines.

The restrictions will again change the routine of air travel, which has undergone an upheaval since the terrorist attacks in New York and Washington in September 2001 and three attempts at air terrorism since then.

Just a day after the attempt on Friday, travelers at airports around the world began experiencing heightened screening in security lines. On one flight, from Newark Airport, flight attendants kept cabin lights on for the entire trip instead of dimming them for takeoff and landing.

The limits, which brought to mind some of the most stringent policies after the 2001 attacks, come at a difficult time for the airline industry.

Travel has declined about 20 percent since 2008 because of the economy, and airlines have been dealing with numerous delays the past week because of snowstorms on the East Coast and in the Midwest.

Airline industry executives said the new steps would complicate travel as vacationers return home from Christmas trips, and could also cause travelers to cancel plans for flights in 2010.

But the Homeland Security secretary, Janet Napolitano, said in a statement Saturday that passengers should proceed with their holiday plans and “as always, be observant and aware of their surroundings and report any suspicious behavior or activity to law enforcement officials.”

The Transportation Security Administration, which governs security at airports and on airplanes in the United States, had no immediate comment on the steps.

The T.S.A. planned to add more security resources as needed on a daily basis, a person with knowledge of the agency’s plans said. The person said travelers would not experience the same thing at every airport, and that the system would be unpredictable by design.

Two foreign airlines, Air Canada and British Airways, disclosed the steps in notices on their Web sites. The airlines said the rules had been implemented by government security agencies including the T.S.A.

“Among other things,” the statement in Air Canada’s Web site read, “during the final hour of flight customers must remain seated, will not be allowed to access carry-on baggage, or have personal belongings or other items on their laps.”

The suspect in the Friday attempt, identified as Umar Farouk Abdulmutallab, 23, tried to ignite his incendiary device in the final hour of the flight while the plane was descending into Detroit.

On its Web site, American Airlines said the T.S.A. had ordered new measures for flights departing from foreign locations to the United States, including mandatory screening of all passengers at airport gates during the boarding process. All carry-on items would be screened at security checkpoints and again at boarding, the airline said. It urged passengers to leave extra time for screening and boarding.

In effect, the restrictions mean that passengers on flights of 90 minutes or less would most likely not be able to leave their seats at all, since airlines do not allow passengers to walk around the cabin while a plane is climbing to its cruising altitude.

The new restrictions began to be instituted Saturday on flights from Canada and Europe to the United States. Air Canada said it was waiving fees for the first checked bag, and it told passengers to be prepared for delays, cancellations and missed connections because of the new limits.

At airport terminals Saturday, travelers recounted the immediate differences they experienced. Though passengers arriving from Frankfurt passed speedily through United States customs at Kennedy Airport in New York, they said that in Germany the security was intensified.

“I really was surprised,” Eva Clesle said about the level of scrutiny in Frankfurt, adding that officials had inspected backpacks by opening “every single zip.”

In Rochester, one passenger waiting in a security line said she saw other passengers removed for additional screening.

The security administration, created in the wake of the September 2001 terrorist attacks, has emergency power to impose restrictions on air travel without consulting the airlines. Its steps have undergone modification in the past, however.

After the 2001 attacks, passengers bound for or leaving Reagan National Airport in Washington were not allowed to leave their seats for the first and last 30 minutes of a flight. The restriction was lifted in 2005.

Passengers still have to remove their shoes before entering screening machines, however, a step instituted at many airports and subsequently made mandatory after Richard C. Reid, the so-called shoe bomber, tried to blow up an American Airlines flight from Paris to Miami in December 2001 by igniting explosives in his shoes.