Field Programmable Gate Arrays (FPGAs) are highly configurable processing devices which offer many benefits such as fast time to deployment, and parallel execution. When they are to be used within a safety critical (or safety related) system, evidence is required which demonstrates that they are fit for purpose and meet system safety requirements. FPGAs are currently not often used in more critical systems due to difficulties providing this evidence. Exploitation of some advanced FPGA features, such as parallelism and reconfigurability, is limited at present due to difficulties assessing the effects of internal faults. In addition, there is limited specific guidance available on producing evidence for the use of FPGAs in the military domain.