How Do Airspeed Indicators And Altimeters Work?

Good Essays

Robert M. Carton
Principles of Accident Causation
March 12, 2017
APT #10

1. How do airspeed indicators and altimeters work?

Both airspeed indicators and altimeters are relatively similar to one another. The airspeed indicator utilizes and receives data from the pitot tube and the static port on an aircraft. In short the air pressure is collected by the pitot tube is compared to the static air pressure to give the pilot an accurate indication of how fast the aircraft is moving. The pitot tube has a small whole in the front and a small whole in the back. It collects ram air pressure from the small hole in the front as it moves through the air. The ram air is directed to the diaphragm (like a balloon) inside of the …show more content…

A radar altimeter uses a C band at 4.3 gigahertz. Radar altimeters are usually in uses when the aircraft is flying at low altitudes (2,500 ft. and below). The difference between the two is one uses frequencies and the other uses static air (Kirchhoff, 2011).
Turkish Airlines Flight 1951 crashed on February 25, 2009 due to a faulty radio altimeter and pilot error. The radio altimeter started producing faults during the final segment of the flight when the aircraft was roughly 2,000 feet above the ground. The captain’s altimeter instantly changed from 1950 ft. to -8 ft. Because the pilots had auto throttles engaged and the aircraft believed it was getting reading to touch down. Therefore, the auto throttles reduced power to retard mode. Retard mode is where the auto throttles automatically reduce power to the engines in preparation to touching down. The pilots noticed the auto throttles reduced power so the first officer manually increased the throttles to maintain appropriate speed to finish the final approach. However, since the first officer failed to hold the throttle lever in position the throttles automatically went back to idle speed. The aircraft stayed at idle speed (100 seconds) until 490 feet above the ground, were the stick shaker was activated indicating the aircraft was about to stall. When the stick shaker was activated the auto throttles advanced to full throttle but

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