A guide to the UK SAIL Mark for UAS designers and manufacturers. It covers what SAIL Marking is and what CAP722K changes at the design stage, how the RAE(F) assessment route works, what a submission involves, when the Mark is worth pursuing and when it is not, and where the UK and EASA review pathways differ.

UAS manufacturers targeting SAIL 3 and SAIL 4 operations must design for EASA SORA compliance from the outset. This guide explains OSO #5, redundancy expectations, DAL C software assurance, reliability requirements, and EASA’s Design Verification Review process.