The Concorde stopped flying 20 years ago, and so far no supersonic aircraft has managed to catch on with the general public. However, projects are multiplying in China, as well as in Switzerland and the United States. In France, the Ecopulse initiative is based on electrical energy. The transport of goods by airship is also a promising avenue... and ecological. This is far from trivial when it comes to building the modes of transport of the future.