(CNN) -- The Transportation Security Administration on Tuesday unveiled a "trusted traveler" program -- one meant to expedite screening at U.S. airport checkpoints, agency chief John Pistole said.
"As with any initiative, we are testing this prescreening concept with a small passenger population at limited airports," he said at an aviation security conference in the Netherlands. "If proven successful, we will explore expanding the program to additional travelers, airports and airlines."
All participants must be U.S. citizens who voluntarily release certain information about themselves.
During its evaluation phase, TSA PreCheck will be available only to certain frequent fliers on American and Delta airlines flying out of certain airports. Delta passengers must be flying out of Atlanta and Detroit airports, and American Airlines passengers must be flying out of Miami and Dallas airports.
It was opened to participants in Custom and Border Protection's Trusted Traveler programs, including Global Entry, SENTRI, and NEXUS.
"As TSA moves further away from a one-size-fits-all approach, our ultimate goal is provide the most effective security in the most efficient way possible," said Christopher McLaughlin, TSA assistant administrator of security operations.
The program won't guarantee expedited security screening, according to Pistole, who said participants would still be subject to "random and unpredictable security measures."
In July, the TSA said it would expand this pilot program to include United, Southwest, JetBlue, US Airways, Alaska and Hawaiian airlines, and additional airports, once operationally ready.
Currently, the TSA vets passenger lists against "watch lists" of known or suspected terrorists. But the TSA is working with a very limited amount of information about those passengers -- namely a person's full name, date of birth and gender. Under trusted traveler programs, travelers voluntarily surrender more information about themselves, giving the government more assurances of who they are.
The amount and nature of the information that will be sought were not disclosed.
There have long been calls for the TSA to adopt a trusted traveler program. Congress and critics have stepped up that demand following two highly publicized incidents, one involving the search of a 6-year-old girl, and the other involving a 95-year-old cancer patient. In both cases, the TSA has said the airport screeners were following established protocols.
But the TSA also has said it is working toward a "risk-based" trusted traveler program that could expedite travel for people believed to present little risk to aviation.
The TSA said in July that Pistole will work with Customs and Border Protection Commissioner Alan Bersin and the airlines to determine passenger eligibility for this screening project, which is voluntary.
All passengers in the pilot project will be subject to recurrent security checks.
Security experts have long expressed concern about so-called clean skins -- potential terrorists who enroll in trusted traveler programs to avoid scrutiny during a terror mission. But the TSA says it will continue to incorporate random and unpredictable security measures to address such concerns.
Pistole said in July that other layers of security will remain in place, including intelligence gathering and analysis, explosive-detection canine teams, federal air marshals, closed-circuit television monitoring and behavior detection officers.
CNN's Mike M. Ahlers contributed to this report.