Air crash investigators at the Paris-based BEA have been working on the theory that the speed sensors, known as pitot tubes or probes, malfunctioned because of ice at high altitude.

So, choose as far as possible to improve the nozzle of small high cutting speed and cutting quality is useful, but the nozzle at low altitude may cause double arc phenomenon.

The trial was conducted at the company's Airbreathing Test Facility in Orange County, Virginia, and involved a full-scale engine tested at conditions simulating high-altitude, high-speed flight.