Welcome to the Obstacle Assessment and Management AirBook. This AirBook will cover various lessons that are essential to aerodrome safeguarding and obstacle control. Our goal in this course is to provide you with an understanding of how obstacles or objects in the vicinity of an aerodrome are assessed and managed, especially if they pose a hazard to aircraft operations around the airport. This course will not only focus on the OLS assessment but also discuss the other aspects that need to be looked at in order to achieve an all-inclusive evaluation and better understanding of the relationships between the different imaginary surfaces that protect aerodromes, flight procedures and CNS facilities. Throughout the course, we will be using mostly ICAO references with the addition of some state-specific examples of best-practices.