The Digital Altimeter Setting Indicator (DASI) System is a critical part of flight control and instrumentation. It assists with calculating the true altitude of an air plane relative to the ground. Pilots use this altitude calculation for landing aircrafts safely on the runway. Without this system, pilots wouldn't have accurate altitude measurements accessible to them prior to landing.
Altimeters, a vital component within an aircraft, calculate and display altitude by measuring the barometric pressure and converting that measurement into altitude. The greater the altitude of the aircraft, the lower the altimeter pressure reading. Altimeters produce readings with respect to sea level. This is an inaccurate reading as a result of weather patterns and varying elevations of airport locations. Changes in weather can alter the readings at an airport control tower. As weather patterns move, high and low pressure fronts change the pressure seen at the fixed location. Since each airport has a unique elevation, using the aircraft's altitude in reference to sea level would greatly mislead the pilot.
A new reading should be taken during each flight so that the altitude can be properly corrected. The altimeter's reading is adjusted through a barometric pressure reading taken at airport control tower, which is then relayed to the pilot prior to landing, ensuring proper landing of the aircraft. Without the altitude adjustment, an aircraft could prepare to land on the runway too soon or too late, causing major safety issues.
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