The expanded testing will not affect most travelers expected to crowd the airports during this year's busy Thanksgiving travel season. But the government has made other changes in the past year that could make for a less intrusive trip through airport security.
Invasive pat-downs and full-body imaging machines are still a central part of the air traveler's experience in the U.S.
But now children 12-and-under are less likely to be patted down or forced to take off their shoes. And about half of the full-body imaging machines have been upgraded to show an outline of a person instead of a blurry naked image, a feature of all new machines the government purchases, Transportation Security Administrator John Pistole told Congress.
The pre-screening test program and policy changes represent the Obama administration's attempts at a more risk-based, intelligence-driven passenger screening program aimed at responding to complaints that the government is not using common sense when it screens all travelers the same way at airports.
Details of which airports and airlines would be eligible for the next round of testing for the pre-screening program are still being hammered out, Pistole said. Currently about 280,000 frequent fliers from American and Delta airlines - the two airlines eligible for the first round of testing - are participating in the program, according to TSA. The program is being tested at airports in Atlanta, Dallas, Detroit and Miami.
"This new screening system holds great potential to strengthen security while significantly enhancing the travel experience, whenever possible, for passengers," Pistole said in a prepared statement at a hearing before the Senate Homeland Security and Governmental Affairs Committee.
But some enhanced security measures put in place at U.S. airports since the 2001 terror attacks continue to be controversial.
Some travelers and privacy advocates object to the intimate pat-down, a measure Pistole called for to give screeners the best chance at catching someone hiding a bomb in his underwear like the man authorities say nearly brought down an airliner over Detroit on Christmas Day in 2009.
Also, not everyone is comfortable going through a full-body imaging machine that produces a blurry image of their naked bodies so that TSA screeners can check for contraband. And there are still complaints about having to take off shoes to go through the machines.
Others are concerned that radiation from the machines is dangerous. Though TSA has said the machines are safe, Pistole told lawmakers he would call for an independent study to evaluate their safety.