As I understand, the free Precheck program is invite-only for frequent fliers, but you can sneak into Precheck if you're a Global Entry program member, which you can apply for online for $100.
> To qualify, frequent fliers must meet undisclosed TSA criteria and get invited in by the airlines. There is also a backdoor in. Approved travelers who are in the U.S. Customs and Border Protection's "Global Entry" program can transfer into Precheck using their Global Entry number.
> To qualify, frequent fliers must meet undisclosed TSA criteria and get invited in by the airlines. There is also a backdoor in. Approved travelers who are in the U.S. Customs and Border Protection's "Global Entry" program can transfer into Precheck using their Global Entry number.