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Guinness World Records formally recognized the NASA X-43A Hyper-X world speed record for an aircraft propelled by an air-breathing engine with this certificate and inclusion of the record into its database. The accomplishment will be included in the 2006 Guinness World Records book, set for release August of 2005, and will appear on their Web site at www.guinnessworldrecords.com.
Their database contains these details: "On 27 March 2004, NASA's unmanned Hyper-X (X-43A) airplane reached Mach 6.83, almost seven times the speed of sound. The X-43A was boosted to an altitude of 29,000 m (95,000 ft) by a Pegasus rocket launched from beneath a B-52B aircraft. The revolutionary 'scramjet' aircraft then burned its engine for around 11 seconds during flight over the Pacific Ocean."