An aeronautical engineer is a professional who designs, develops, and maintains aircraft and spacecraft. They apply principles of physics, mathematics, and engineering to create safe and efficient flying machines. Aeronautical engineers work on various aspects of aircraft design, including aerodynamics, propulsion systems, materials, and structures. They may also be involved in testing, analyzing performance, and ensuring compliance with safety regulations. Overall, aeronautical engineers play a crucial role in advancing aviation and aerospace technology.