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What is QFE in Aviation? (The Q Code For: Atmospheric Pressure At Aerodrome Elevation (Or At Runway Threshold))

Updated: March 08, 2024

Understanding QFE: Atmospheric Pressure at Aerodrome Elevation

Aviation is a fascinating field that encompasses a vast array of technical terms and jargon. One such term is QFE, which stands for Atmospheric Pressure at Aerodrome Elevation (or at runway threshold). QFE plays a crucial role in aviation operations, particularly during takeoff and landing. In this article, we will delve into the significance of QFE, its measurement, and its impact on flight operations.

The Significance of QFE

QFE, as a measure of atmospheric pressure at aerodrome elevation or runway threshold, is essential for pilots to accurately determine their aircraft's altitude above the ground. It provides a reference point that allows pilots to make precise judgments during takeoff and landing. By setting the altimeter to the QFE value, pilots can ensure that their altitude readings align with the actual height above the aerodrome or runway threshold.

When an aircraft is flying at a higher altitude, the atmospheric pressure decreases. However, when it descends closer to the ground, the pressure increases. This change in pressure can significantly affect altitude readings if not accounted for. By setting the altimeter to QFE, pilots eliminate the impact of atmospheric pressure fluctuations, resulting in more accurate altitude measurements during critical phases of flight.

Measurement and Usage of QFE

The measurement of QFE involves determining the atmospheric pressure at the aerodrome elevation or runway threshold. This is typically done using a barometer or pressure sensor. The obtained pressure reading is then converted into a QFE value, usually expressed in hectopascals (hPa) or inches of mercury (inHg).

To ensure safety and precision in aviation, QFE is used in conjunction with other altitude reference systems, such as QNH (atmospheric pressure at sea level) and QNE (standard pressure setting). While QNH provides a reference for altitude above mean sea level, QFE allows pilots to know their altitude above the aerodrome or runway threshold.

During takeoff and landing, pilots typically receive QFE values from air traffic control or the automated weather information system at the aerodrome. They then adjust their altimeters accordingly, ensuring that altitude readings reflect the aircraft's height above the ground. This practice is crucial for maintaining safe separation between aircraft and the ground during critical phases of flight.

The Impact of QFE on Flight Operations

The accurate use of QFE is vital for safe and efficient flight operations. By setting the altimeter to the QFE value provided by air traffic control, pilots can ensure that their altitude above the aerodrome or runway threshold is correctly indicated. This is particularly crucial when operating in areas with varying terrain or when landing on short runways.

Incorrectly set altimeters can lead to disastrous consequences. If a pilot fails to adjust their altimeter to the correct QFE value, they may misjudge their altitude above the ground, potentially resulting in a hard landing, collision with obstacles, or even a runway overshoot. These scenarios highlight the importance of precise altitude measurements facilitated by QFE.

It is worth noting that QFE is primarily used in military aviation operations or in certain specific situations, such as helicopter operations. In most civilian aviation operations, the standard practice is to use QNH, which provides a reference to altitude above mean sea level. However, understanding QFE remains essential for pilots to ensure safe operations in environments that require this altitude reference system.

In conclusion, QFE, as a measure of atmospheric pressure at aerodrome elevation or runway threshold, plays a critical role in aviation operations. Pilots rely on QFE to accurately determine their altitude above the ground during takeoff and landing. By setting their altimeters to the QFE value provided by air traffic control, pilots can ensure precise altitude readings, enhancing safety and efficiency in flight operations. Understanding the significance of QFE and its proper usage is paramount for every pilot, as it ensures the utmost safety during critical phases of flight.

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