Above Field Elevation (AFE) is an important term used in aviation to describe the altitude or height above the elevation of an airfield or airport. It refers to the vertical distance between an aircraft and the ground or terrain surrounding the airfield. AFE is typically measured in feet or meters and is a crucial factor in determining safe altitudes for takeoff and landing procedures.
AFE plays a significant role in the planning and execution of flight operations, as it affects various aspects of aircraft performance, obstacle clearance, and navigational procedures. Prior knowledge of AFE helps pilots make informed decisions regarding altitude selection and obstacle avoidance, ensuring safe and efficient operations during all phases of flight.
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Why is Above Field Elevation Important?
Understanding AFE is essential for flight planning and conducting safe operations in and around airports. Here are a few key reasons why AFE is crucial in aviation:
Aircraft Performance
AFE directly affects aircraft performance, especially during takeoff and landing. At higher altitudes, the air density decreases, which reduces engine performance and aircraft lift. Therefore, pilots need to consider AFE while calculating the required runway length and determining takeoff speeds to ensure sufficient runway distance for a safe and successful takeoff. Similarly, during landing, pilots utilize AFE to determine the appropriate touchdown point and touchdown speeds while considering the aircraft’s deceleration capabilities within the available runway distance.
Obstacle Clearance
AFE is crucial for obstacle clearance during takeoff, climb, approach, and landing procedures. It helps pilots maintain a safe altitude above ground level and ensures adequate clearance from natural or man-made obstacles such as buildings, towers, hills, and trees. By accounting for AFE, pilots can select appropriate departure and arrival procedures that avoid potential obstacles or comply with the required obstacle clearance requirements published in aeronautical charts and approach plates.
Furthermore, knowledge of AFE assists pilots in making timely decisions in case of an engine failure during takeoff or climb. By understanding the AFE and the surrounding terrain, pilots can choose the best course of action, such as the selection of an emergency landing site or opting for a revised climb gradient to clear obstacles ahead. This information is crucial for maintaining the safety of passengers and crew onboard the aircraft.
AFE is also necessary for accurate navigational procedures, including instrument approaches and departures. Flight navigational charts and approach plates provide altitudes or minimum descent altitudes (MDA) specified above the field elevation. Pilots refer to these altitudes, taking into account the AFE, to ensure proper vertical guidance during the approach and landing phase. Precise adherence to these altitudes ensures safe separation from the terrain and obstacles around the airport.
Moreover, the use of AFE in navigation assists pilots in determining the correct altitudes for step climbs or descents during en route flights, optimizing fuel efficiencies and complying with air traffic control instructions. By monitoring the AFE and adjusting their altitude accordingly, pilots can navigate through controlled airspace without compromising safety.
Conclusion
Above Field Elevation (AFE) is a critical aspect of aviation that pilots and air traffic controllers must consider during flight planning and operations. It influences aircraft performance, obstacle clearance, and navigational procedures, making it imperative for safe and efficient aircraft operations at and around airports.
By understanding the importance of AFE, pilots can make informed decisions regarding altitudes, obstacle avoidance, and compliance with established procedures. Their knowledge of AFE ensures the safety of passengers, crew, and the aircraft itself.
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