OK, lots of terms being thrown around here, and it seems confusing as to what applies when. So here goes my understanding, in the hope it clarifies. (skip to the end if you don't want the details).
There are three facets of travel that different programs cover - security prior to boarding, immigration when arriving in a country (are you allowed in?) and customs (are you allowed to bring in what you are bringing with you). I am going to restrict this discussion to flying - not land border crossings
The
TSA (Transportation Security Administration) is a US operation, run by the U.S. Government - it deals with security checks for passengers. It is part of the Department of Homeland Security. It does not exist outside of the USA (although other countries will have their own agencies doing a similar function, of course).
TSA Pre-check is a stand-alone program that on its own costs $85 for 5 years. When you apply, the TSA does a background check on you and, if you pass, you are in - you get a so-called "
Known Traveler Number". When you enter this into your ticket when you buy it, for US Airlines and some others, this pretty much (but not completely) guarantees that you will get that "TSA Pre" text on your boarding pass so that when you check in to a U.S. Airport (not those in a foreign country) you can go through the expedited security lanes, if they are open. However, it is not guaranteed - they may randomly not give you this, to make you go through the regular security. TSA Precheck is currently available at 200 airports and with around 75 carriers. For it to kick in, you would need to be going through an airport where it is available and flying an airline that is one of the listed carriers. See the current list at:
TSA Pre✓® Airports and Airlines
TSA Pre-Check is for leaving the USA, nowhere else.
Some credit cards and loyalty programs carry a benefit of covering the application fee in some way. See here for a current list:
Credit Cards and Loyalty Programs featuring TSA Pre✓®
There are other ways of getting the Known Traveler number, as below.
Global Entry is a program offered by the U.S. Customs and Border Protection. It allows pre-approved, low-risk passengers to go through expedited clearance (immigration and customs) on arrival in the U.S. It does not cover arrival in any other airport. It is available at 54 airports. The fee for an application is $100. The approval is good for 5 years. Only nationals of certain countries can apply for Global Entry (see
International Arrangements | U.S. Customs and Border Protection). In some cases (sometimes random, sometimes not) even with Global Entry approved and at an airport where kiosks are offered, you may have to go through full immigration and customs checks. Being approved for Global Entry also approves you for TSA Pre-check availability.
Pre-clearance - some airports not in the US provide customs and immigration pre-clearance. They do this by stationing permanently members of the U.S. Customs and Border protection at those airports, operated by the U.S. government. Some of these pre-clearance airports also have Global Entry kiosks. There are currently 15 pre-clearance airports, listed here:
Preclearance Locations | U.S. Customs and Border Protection - all passengers on a flight need to get the pre-clearance, as there will be no checks on arrival to the U.S. There is no extra cost to the passenger for this.
For a list of airports with Global Entry kiosks, see this link:
Airports with Global Entry Kiosks | U.S. Customs and Border Protection
Global Entry, therefore, is for arriving into the US, nowhere else.
NEXUS - is a joint program by Canada and the USA (so it's not just a Canadian thing). It is used for entry into Canada, and into the US (whether coming from Canada or not) - passengers entering the US will use the Global Entry kiosks. An application requires a security check from both US and Canadian authorities. The only people that can apply for it are citizens or permanent residents of Canada or the United States or citizens of Mexico that hold a
Viajero Confiable membership. The application fee is $50. It is valid for 5 years. So Nexus gives you Global Entry and TSA Pre-check.
Mobile Passport - this is an app for your phone, available for Apple and Android devices. You install the app, enter in your passport information, then, when you land in the US you enter in your information (photo, flight info, customs information) - you get an electronic receipt with a QR code on it. You then go through a special lane with this receipt and your passport and go through immigration and customs. It is free, but does not give you TSA Pre-check. It is also only available in some airports. For a list of airports, see:
Mobile Passport Control | U.S. Customs and Border Protection - again, this is a US-only program.
For Cayman travelers, the notable absence from this list is Charlotte (CLT). Philadelphia (PHL) is also missing, but Miami is in the list.
Clear is a registered traveler program. The information is collected by a private company in partnership with the TSA. An applicant provides personal information and biometrics to the company, which then works with the TSA to do a background check. Once approved you get a card. It is only available to US citizens and legal permanent residents 18 and older.
Clear does not give you TSA Pre-check or Global Entry. You just jump to the front of the lines in places it is available - for that list see here:
https://www.clearme.com/where-we-are (Miami is in, Philly and Charlotte not).
Annual member fee is $179, for the first member of the family, and $50 per year for additional family members.
The initial Clear company went bankrupt, and has restarted under a different company.
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tl;dr version:
So none of this really helps anything going on in Cayman airports, whether arrival or departure. It does help on re-entry to the USA, or if you have a split itinerary where you have to take your bags land-side in the USA and recheck them, and have to go through security again.
If you use an entry airport that can take the mobile passport app that is probably going to work well for you, and it's free, but it doesn't give you TSA Pre-check, which may be an issue for you. So paying the $85 for 5 years just for that might be worth it.
After that NEXUS is by far the cheapest, and it gives you Global Entry and TSA Pre, but you need to be able to get to a location for an interview, and you may not live close to one of those. Next best is Global Entry. Clear, to me, just isn't worth the cost for the amount of flying I do.