This paper provides an overview of the problems associated with heavy truck air brakes. Overall truck accident experience is examined, and an assessment made of the effect that improved braking could have on reducing accident frequency. The controversial Federal Motor Vehicle Safety Standard (FMVSS) 121 brake standard is reviewed together with the maintenance and reliability problems that led to its rescission. Current brake technology is discussed and the stopping distances that can be expected from trucks are theoretically and experimentally evaluated. The effect that out-ofadjustment brakes have on these stopping distances is assessed. Finally, improvements that can be expected from new brake technology are reviewed, and the feasibility and practicality of a new brake safety standard discussed in relation to European brake regulations.