Space-Available Travel (Space-A Travel)
Space Available (Space-A) travel allows authorized passengers to occupy Department of Defense (DoD) aircraft seats that are surplus after all Space Required (Space-R) passengers have been accommodated. Space-A travel costs nothing but is allowed only on a non-mission interference basis.
As of 9 Jun 2015, in recognition of the sustained efforts of Spouses and dependent Children of deployed military members, the Department of Defense (DoD) policy on Space-A for dependents of deployed members is being updated to reflect the recommendation of the Military Compensation and Retirement Modernization Commission Recommendation Assessment. Effective immediately, dependents of military members deployed for 30 or more consecutive days are authorized to travel Space-A on DoD aircraft in Category IV. This change will be incorporated into DoD Instruction 45 15.13R, "Air Transportation Eligibility," which is currently under revision.