65 years ago, a Douglas DC-8 beat the Tu-144 and Concorde to break the sound barrier first

Exactly 65 years ago, on August 21, 1961, the Douglas DC-8 became the first commercial airliner to break the sound barrier. This milestone was achieved eight years before the first supersonic flights of the Soviet Tu-144 and the Anglo-French Concorde, which were later specifically designed for sustained supersonic travel.

The experimental DC-8-43 took off from Edwards Air Force Base in California. The aircraft was already painted in the livery of its future operator, Canadian Pacific, and was scheduled to be used on regular commercial routes after the test program was completed.

During the flight, the aircraft climbed to an altitude of approximately 15,267 meters (50,090 feet). Pilot William Magruder then put the four-engine airliner into a controlled steep dive to accelerate it beyond the speed of sound.

As it passed through about 12,524 meters (41,088 feet), the DC-8 reached Mach 1.012 — roughly 1,075 km/h (668 mph) under those conditions — and maintained supersonic speed for about 16 seconds. In this way, an ordinary subsonic passenger liner officially broke the sound barrier for the first time.

The primary goal of the experiment was not to set a record. Douglas engineers were gathering aerodynamic data and testing a new wing leading edge design intended to reduce drag. The brief supersonic burst allowed them to study the aircraft's behavior under extreme conditions that it would not normally encounter in regular service. This flight provided crucial data on control characteristics, structural loads, and aerodynamic heating during a supersonic dive, which helped improve the design of future commercial aircraft. The achievement also demonstrated that a well-built subsonic airliner could safely withstand the stresses of crossing the sound barrier, even if only briefly.