The Singapore Airlines Group with its subsidiaries covers a range of airline-related services from cargo to engine overhaul. The main subsidiaries are SIA Cargo, SIA Engineering Company, SilkAir and Tradewinds Tours and Travel. The Company has organized into business units based on the nature of the services provided, and has four reportable operating segments including The airline operations segment provides passenger air transportation; The engineering services segment is in the business of providing airframe maintenance and overhaul services, line maintenance, technical ground handling services and fleet management programme; The cargo operations segment is involved in air cargo transportation and related activities and Other services provided by the Group, such as training of pilots, air charters and tour wholesaling, has been aggregated under the segment Others.