SUMMARY: This final rule amends the requirements in the Hazardous Materials Regulations (HMR) for the transportation of hazardous materials by aircraft. This final rule clarifies the applicability of part 175; clarifies the exceptions from regulation for operator equipment and supplies, special aircraft operations, and passengers and crewmembers; revises separation distances for the shipment of radioactive materials by cargo aircraft; and updates the regulations to comply with security requirements for explosive special permits. These changes are being made to finalize outstanding petitions for rulemaking, convert certain special permits into regulations, and promote international harmonization, where appropriate.