Should all NPIAS airports have an ACM? – By now you should understand that Part 139 only applies to a small percentage of U.S. airports. You should also know that only airports operating under Part 139 require an Airport Compliance Manual (ACM). However, given the nature of aviation and the high demands it places on airports of all types (commercial, reliever, and general aviation), why should only a small number of airports require an ACM. argue either for or against this requirement.