Carrier onboard delivery (COD) is the use of aircraft to ferry personnel, mail, supplies, and high-priority cargo, such as replacement parts, from shore bases to an aircraft carrier at sea. Several types of aircraft, including helicopters, have been used by navies in the COD role. The Grumman C-2 Greyhound has been the United States Navy's primary COD aircraft since the mid-1960s.

A spare part, spare, service part, repair part, or replacement part, is an interchangeable part that is kept in an inventory and used for the repair or refurbishment of defective equipment/units. Spare parts are an important feature of logistics engineering and supply chain management, often comprising dedicated spare parts management systems.