How Do Aircraft Get To Know Their Altitude?

In the simplest terms, altitude can be defined as the vertical distance between an object and a reference point. However, when it comes to aircraft, measuring altitude can be complicated. To better understand how aircraft efficiently measure altitude, we will discuss what instruments are used by pilots to gauge exactly how far they are from the ground.

The altimeter is a widely used instrument applied in aircraft for measuring altitude. To measure one’s exact altitude while in the sky, an altimeter takes note of the atmospheric air pressure outside of the plane and tells pilots how high they are flying. Calibrating the altimeter is up to the pilot as atmospheric pressure can fluctuate due to changes in weather. This depends on the current weather phenomena happening outside of the airplane, and it keeps changing as the changes in air mass and temperature fluctuate. As such, pilots rely on air traffic controllers to constantly update them about changes in atmospheric pressure to adjust the altimeter settings accordingly.

Altimeters Explained:

It is normal for aircraft to have a form of pressure-sensitive altimeter present at all times. Though altimeters are a reliable and simple   instrument for measuring an aircraft’s altitude at any point in the sky, they have certain limitations that must be taken note of.

As a flight takes off and the aircraft begins to climb in altitude, the air pressure starts to simultaneously go down which causes a sealed chamber present inside the altimeter to expand. The amount the sealed chamber expands can be measured using similar equipment to the hands of an analog clock. Additionally, altimeters are calibrated to utilize the average decrease in atmospheric pressure that is found under normal conditions. For every 1,000 feet of climb, the standard lapse rate is 1.00″ Hg.

The Right Way to Read an Altimeter:

Like a clock, altimeters have a big and a small hand that gradually moves between digits. The big hand is typically present to denote increments of 1,000 feet, while the small hand represents individual feet. Each number indicates 100 feet and small dashes located between numbers indicate 20 feet. An additional outer needle, which can be easy to miss, indicates tens of thousands of feet and is used only when aircraft are flying above 10,000 feet.

There are many types of altimeters. For example, radio altimeters are used in planes that have radar altimeters incorporated in them. Radar altimeters are known to be large and expensive, and are typically found in the big transfer category airplanes. However, they are a critical part of operating larger aircraft as they operate as a crucial safety backup system.

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