Do military pilots use amphetamines or other stimulants?
The U.S. Air Force (and Navy) still uses, and has used off and on since WWII,  what are commonly referred to as "Go Pills" for instances when pilots need to be up for long periods of time - in wartime, sometimes longer than the crew rest regulation. (These pills can also be used for altering sleep cycles, along with "no-go" pills; for example, when changing from day to night).

The most common go pill is Dexedrine, which is an amphetamine. You can find some more information in this article.