Turns out the US government has a secret passenger airline. Area 51 workers are shuttled in from the Las Vegas airport every day on the passenger jets, which are owned by the US Air Force. The fleet is made up of 11 planes, and is commonly referred to as JANET airlines. While some joke JANET stands for "Just Another Non-Existent-Terminal," it may actually mean "Joint Air Network for Employee Transportation."
Don't expect to be flying JANET anytime soon — even the flight attendants are required to have top-secret clearance.