This book gathers the latest advances, innovations, and applications in the field of aerospace technology and aviation safety, as presented by researchers at the 9th World Congress “Aviation in the XXI Century”: Safety in Aviation and Space Technologies, held in Kyiv, Ukraine, on April 26-28 2021. It covers highly diverse topics, including carbon neutral aviation, precision engineering in aerospace, robots in the aerospace industry, nanotechnology for aerospace, aircraft design and strength, tribotechnology in aviation, engines and power installations, intelligent robotic and measuring systems, control systems, civil aviation cybersecurity, mathematical modeling and numerical methods, aeronavigation, unmanned aerial complexes, environmental safety and aviation chemmotology, aviation transport logistics, and construction of transport facilities. The contributions, which were selected by means of a rigorous international peer-review process, highlight numerous exciting ideas that will spur novel research directions and foster multidisciplinary collaborations.