On this day, 55 years ago, on March 25, 1970 (February 18, 1970, the world's first passenger plane flying at supersonic speed was successfully tested. On March 25, 1970, the "Concorde" passenger plane successfully flew at supersonic speed, becoming the world's first passenger plane to fly at supersonic speed and the only supersonic commercial passenger plane in the world to be put into operation on the route. However, since it was designed in the 1960s, the technology used can only represent the technical level of the 1960s, so there are two major flaws: poor economy and too loud noise during take-off. On October 24, 2003, Concorde carried out its last flight and all were retired.