This is the first significant change to the checkpoint since the 1970s," TSA chief Kip Hawley said.

The checkpoint to be tested in May at one terminal in Baltimore is based on a simple premise: serenity adds security. Mauve lights glow softly, soothing music hums, and smiling employees offer quiet greetings and assistance.
 

"A chaotic, noisy, congested checkpoint is a security nightmare. Chaos gives camouflage," Hawley said. "A chaotic environment puts subtle pressure on (screeners) to rush the job."

Hawley has sought to "calm the passenger" as he has focused the TSA on intercepting terrorists before they get to checkpoints, where they could slip plastic explosives past X-ray machines. About 1,200 screeners at 70 large airports specialize in passenger observation and pick out people who appear suspicious for closer questioning or pat-downs.

That task is easier if passengers are relaxed. "Calm allows things to stand out more," Hawley said. "It creates a better environment to observe hostile intent."

TSA planners have been tinkering for months in a warehouse at Ronald Reagan Washington National Airport, testing music, lighting and displays. "You can actually influence some behavior subliminally through color," said Catherine Lillie, head of the checkpoint-testing team.

The TSA test in Baltimore will refine the strategies, which could be exported to other airports.

The test will include a machine that uses harmless radio waves to scan passengers under their clothes for hidden weapons. Passengers will be selected randomly for the scanning after they go through a metal detector. Screeners will view images of passengers' bodies in a remote room and delete them.

Charles Chambers, head of security for the Airports Council International, said the new checkpoint could speed security lines and reduce crowds that may invite a terrorist strike.

"Some airports do have concerns about large groups of people," Chambers said. "Anything you can do to disperse people quicker is a good thing."