Benet Wilson is one of the 2.5 million Americans who have paid a yearly fee to skip security lines at airports and thinks it's worth every penny she paid for a five-year membership in the Global Entry program offered by the U.S. Customs and Border Protection department.

    "It's a beautiful thing," says the 50-year-old frequent flier, who writes the AviationQueen.com blog.

    Earlier in June, Wilson was traveling back to Washington Dulles International Airport from a conference in Qatar, and walked right past an enormous customs line that had a wait time of nearly an hour.

    Instead, she was in a car on her way home about 40 minutes after her plane touched down.

The value of spending $100 for Global Entry comes down to how often you fly. Adding $100 per person plus the application time and in-person interviews probably is not worth it for a one-time family vacation to Europe.

    But those who frequently travel abroad say participation pays off. As an added benefit, participants also have a better chance to minimize security delays on domestic flights.

HOW IT WORKS

The Global Entry program's automated kiosks require users to answer a couple of on-screen questions, scan passports, place their fingertips on a screen and get a printout to present at the exit. The process takes a couple of minutes.

    Kiosks are now available at 44 airports (including 10 in Canada and Ireland).

    The time savings can be significant. This year, the average wait time for customs has been about 20 minutes at six major U.S. airports. Yet a Reuters analysis indicates that waits of well over two hours are not unusual.

    Wilson raved about the program, which she said she has participated in since it was a pilot project in 2008. It became permanent in 2012.

"This is one of the best $100 I've spent on travel," she said.

It can take time to get approved. There is a wait time for some applications for Global Entry (goes-app.cbp.dhs.gov/main/). The process involves an in-person interview and fingerprinting. An applicant needs to provide basic personal information, plus passport number, driver's license number, employment history, addresses going back five years and five years of international travel history.

    Fewer than 5 percent of applicants for Global Entry are denied. Issues that could disqualify an applicant include: criminal charges, customs violations and ongoing investigations by law enforcement. The government could also deny approval if it is unable to document where an applicant has lived, worked, or whether he or she has committed a crime.

    Joe Sobin, 47, a travel consultant who works in Denver and New York, said he was on a three-month wait list for an interview in Denver and instead went to John F. Kennedy Airport in New York, where he quickly got an appointment.

Global Entry is one of several U.S. Trusted Traveler programs. There are also programs for expedited passage between the United States and Canada and the United States and Mexico.

One obvious hitch with Global Entry comes when a person who is approved travels with others who do not have the same status. Children 12 or under need their own Global Entry identification.

    And while the program allows travelers to zip through customs, those who bring luggage on an international flight still have to wait at the baggage claim with everyone else.

FOR DOMESTIC TRAVELERS

In December, the Transportation Security Administration added its own $85 program aimed at domestic travelers called TSA PreCheck. It now has more than 300,000 members and is enrolling about 3,500 people a day, spokesman Ross Feinstein says. Anyone with Global Entry automatically qualifies.

    PreCheck gives participants access to boarding passes which give them a chance to skip the main security line and bypass some screening procedures such as taking off their shoes.

But PreCheck does not guarantee a line-skip. Participants must wait until they receive a boarding pass to find out whether they have made the cut for that flight. If the program status is not noted on the boarding pass, a PreCheck participant must wait with everyone else.

One upside: Children who are 12 under may zip through lines with a parent who has PreCheck approval.

PreCheck has the same value proposition as Global Entry. If someone travels enough, it could be worth spending the time to apply and paying $85 for a chance to bypass the main security lines. Some frequent travelers lament that even the "special lines" get bogged down, because other travelers are selected at random to go through, as well.

PreCheck participants must enter a Known Traveler Number when making reservations, or have it saved as part of a profile with the airline.

Applicants for TSA PreCheck (www.tsa.gov/tsa-precheck) must schedule interviews 45 days in advance. PreCheck can be used at 118 U.S. airports on the following 11 airlines: Air Canada, Alaska Airlines [ALKAIR.UL], American Airlines, Delta Air Lines, Hawaiian Airlines [HAII.UL], JetBlue Airways, Southwest Airlines, Sun Country Airlines, United Airlines [UALCO.UL], US Airways [LCCUA.UL] and Virgin America.

(Follow us @ReutersMoney or here Editing by Beth Pinsker, Lauren Young and David Gregorio)