Aviation safety is the paramount concern, and numerous procedures are in effect to ensure that the air carriers with which AMC contracts afford the highest level of safety to Department of Defense passengers. Prior to receiving a contract, all carriers must demonstrate that they have provided substantially equivalent and comparable commercial service for one year before submitting their offer to fly for the Department of Defense. All carriers must be fully certified Federal Aviation Administration carriers and meet the stringent standards of Federal Aviation Regulations pertaining to commercial airlines (Part 121).