All security measures are in place, including passport checks, baggage X-ray and screening for explosives, and shuttle buses linking terminals will operate normally.

A baggage X-ray machine broke down in the vast departure hall, creating just the kind of long lines that it was hoped Terminal 4 would do away with.

While the lines ebb and grow depending on the airport and time of day, many passengers said the biggest difference was the wait at the metal detector and baggage X-ray.

It is equipped with CCTV cameras, two Baggage carousels in the arrivals hall and one hand baggage X-ray machine, among other modern facilities.

Continental has sued United to force it to remove metal templates on baggage X-ray machines that prevent passengers, including Continental's, from carrying large bags onto airplanes at Dulles Airport near Washington.

At the US Airways Terminal at La Guardia in the late morning, police officers guarded the boarding areas with bomb-sniffing dogs, and lines were long at baggage X-ray machines.

In Budapest, though, a British executive said that two weeks after the attacks on the United States he stood in line for two hours awaiting an extra passport check, baggage X-ray and body search before he could even reach the check-in desk.

In order to prevent a terrorist with a clean background from compromising the system, the TSA requires that registered travelers undergo the normal TSA screening (baggage x-ray and personal metal detector), at the RT kiosk checkpoint.

On the way to Rome, airline security personnel had conducted random body and luggage searches on passengers at the gate in addition to the usual baggage X-ray and body-screening that has been standard at European airports since the hijackings of the 1970's.

At the New Delhi airport, which at any time of day or night feels like Times Square on New Year's Eve, I somehow made my way through the crowds until I arrived at security and the baggage X-ray station.

Passenger complaints meanwhile were not limited to just the lack of air conditioning: despite the existence of a baggage X-ray machine, passengers flying other airlines were forced to have their baggage manually checked as the machine was ostensibly for the sole use of Philippine Airlines passengers.