If you are a member of the military, it is possible for you to partake in travel at little or no cost. Congress decided many years ago that one way to show appreciation for the military would be to allow military Servicemembers to travel on military aircraft that had extra room or whose seats were not entirely filled by the mission or the flight. This privilege is referred to as Space Available travel, or Space A for short. It is an effective method of travel, but one that requires that you have patience and some travel plan flexibility.
You have to be active duty military, a dependent of active duty Servicemember, a retired veteran, or one of a select group of active reservists. That’s it. The Space Available program is not available to the general public. Basically the premise is simple: You go to a airfield that military flights fly in and out of, and go to the military aircraft Terminal. You can at times pre register for flights, or you can register at that time, the day of travel. If a flight heads out of the airfield, that is not entirely filled, or has space available on it, that is not used by the mission or military personnel that is traveling under orders, then you qualify to ride, for free.
This sounds like a good deal, and it is. However there are some things to remember about the Space Available program. For one, it is a privilege, one that is subject to change without notice. The best example of this is what happened in the days after September 11th, 2001. The flight schedules for aircraft flights used to be public information, and you could access them until 9-11 on the Internet. After the twin towers tragedy, the program was nearly canceled, it was immediately seen as a possible risk and security danger. The program was not canceled, but it went through a lot of changes, such as the schedules not being publicly available ahead of time. You can still get information, but it is a lot harder now.
Another issue is flexibility. If you have plenty of time, and flexibility in your schedule you can often find a military flight with extra room. In that case, it is a great deal. But it is important that you be prepared in an emergency to book a commercial ticket, and that you have the money to do so. Finally, you have to be a little adventurous to fly Space Available. You may ride on a jet, or a propeller plane. You could fly in a comfortable seat if on a passenger craft, or on a rough crew seat with a helmet next to pallets of cargo for bongo bongo. If this is okay with you, then the Space Available method of travel may work well for you.