Abstract
Obstacle defines all fixed and mobile objects, or parts thereof, that are located on an area intended for the surface movement of aircraft or extend above a defined surface intended to protect aircraft in flight or stand outside those defined surfaces and that have been assessed as being a hazard to air navigation. The airspace around airports are maintained free from obstacles so as to permit the intended aeroplane operations at the airports to be conducted safely and to prevent the airports from becoming unusable by the growth of obstacles around the airports. This is achieved by establishing a series of obstacle limitation surfaces or airspace imaginary surfaces that define the limits to which objects may project into the airspace. This is a case study that shows an application of obstacle limitation criteria, which must be maintained free from an critical obstacle, for specific conditions of two airports. For the purpose of the application, aeronautical studies/flight safety influence assessments were used to identify possible solutions and select a solution that is acceptable without degrading aviation safety.