Instrument Rating Checkride Practice Test

What is the 40:1 Obstacle Identification Surface used for?

1. To identify the nearest fuel station

2. To determine traffic patterns

3. To assess obstructions that impact flight safety

4. To establish flight school boundaries

The correct answer is: To assess obstructions that impact flight safety

The 40:1 Obstacle Identification Surface is primarily utilized to assess obstructions that could impact flight safety. This surface serves as a safety measure to help pilots and air traffic controllers identify potential obstacles in the approach and departure paths of an aircraft, ensuring that these obstacles do not pose a threat during critical phases of flight, particularly in the vicinity of airports. The ratio indicates that for every 40 feet of horizontal distance from the airport, the aircraft should be able to clear obstacles that are 1 foot in height. By employing this surface, the aviation community can effectively manage airspace and promote safe flight operations, particularly during instrument approaches and departures. Understanding this surface allows pilots to be more aware of their environment and formulates adequate measures for safe flight paths, which is crucial for aviation safety. The other options do not pertain to the purpose of the 40:1 Obstacle Identification Surface. Identifying fuel stations, determining traffic patterns, and establishing flight school boundaries refer to different aspects of flight operations or logistics that are not covered by the obstacle identification parameters.