The Guinness Book of Records has officially recognised the world speed record set by Nasa's X-43A hypersonic aircraft earlier this year.
The record may not stand for long
The 3.6m-long scramjet achieved Mach
6.83 - nearly seven times the speed of sound - in a flight on 27 March.
The record is set to be included in the 2006 Guinness World Records book.
But the record may not stand for long, because another X-43A flight in October aims to smash it by flying to Mach 10 - 10 times the speed of sound.
In the March flight, the unmanned experimental craft was boosted to an altitude of 29,000m (95,000ft) by a rocket launched beneath an aircraft.
It then burned its engine for around 11 seconds during a flight over the Pacific Ocean.
Scramjets burn hydrogen as fuel but take their oxygen from the air, which is forced into the engine at very high speed.
In contrast, rocket engines have to carry their own source of oxygen in heavy tanks.
Scramjet technology could lead to single-stage-to-orbit space vehicles - spacecraft that fly into space in one piece. This would substantially reduce costs in the space delivery business and - eventually - the prices we pay for all our telecommunications.
All shapes and types
The X-43A flight easily broke the world speed record for an air-breathing engine aircraft. The previous known record was held by a ramjet-powered missile, which achieved slightly more than Mach 5.
The highest speed attained by a rocket-powered plane, Nasa's X-15 aircraft, was Mach 6.7. The fastest air-breathing, manned vehicle, the SR-71 "Blackbird" spy plane, achieved slightly more than Mach 3.2.
Commercial airliners fly just below Mach 1 (1,194km/h or 741mph).
The term scramjet stands for supersonic combustion ramjet.