Within 40 years of experiences in Guiding, Navigation & Control, gained firstly in Sonar and then in Aerospace fields, Marc REVOL has contributed since the begining to the design and development of EGNOS and Galileo systems and infrastructures, and to their implementations in operationnal equipments for Aviation and Defence navigation devices. Recently retired from Thales, he is now founder of TILT (Tiptop Innovating Localisation Technologies), an consulting and engineering company which expertise mainly relates to the definition of robust GNSS centered localisation, sensing and navigation applications, for safety of life and critical operation, in harsh environments.