A pitot-static system is a system consisting of static air pressure and dynamic pressure due to motion of an aircraft through air. The combination of these two pressures is key in aircraft operation because it is the driving force of an aircraft’s airspeed, Mach number, altitude and altitude trend. Failure of this system can be extremely dangerous and can result in life-threatening situations. In order to ensure a system is functioning properly and precisely, it is vital to have all components within the pitot-static system calibrated on a frequent basis.
COMPONENTS OF A PITOT-STATIC SYSTEM
A pitot-static system is made up of several important components. Each component plays an important role within the system; therefore it is crucial that each individual component is working properly and accurately.
The L-shaped pitot tube is a device located on the exterior of an aircraft with the purpose of measuring airspeed. It contains a small opening at the front that allows total pressure to enter. This total pressure is then transmitted to the airspeed indicator (ASI) through a tiny tube. Once the dynamic and static pressure is delivered to the ASI, airspeed is indicated.
The pitot tube also has smaller hole located in the posterior of the tube. This small opening functions as a drain for moisture intakes during precipitation.
The static port is located on the side of an aircraft and functions as a small air inlet. Its purpose is to measure static air pressure, also known as barometric pressure. The pressure within the static port is collected and then utilized by the altimeter and the vertical speed indicator (VSI).
Many aircrafts will contain multiple or alternative static ports in case of possible blockage.
The pitot-static system consists of three instruments, including:
The airspeed indicator (ASI) is a sensitive pressure gauge that measures the difference between the pitot and the static pressure. This instrument must be properly calibrated to ensure measurements are precise and accurate. If the airspeed indicator is reading improperly, airspeed can fluctuate which could result in high safety risks.
The altimeter is one of the most important instruments installed in an aircraft. This is because it measures the height of an aircraft above a given pressure level. The proper settings for an altimeter can’t be overemphasized; therefore frequent maintenance and calibration is a necessity. If the altimeter is not functioning properly or is not on the correct setting, a pilot will not be able to determine the altitude.
The vertical speed indicator (VSI) is responsible for indicating whether an aircraft is climbing, descending or in level flight. If this instrument is properly calibrated, the VSI should read zero. Proper functionality of the VSI is pivotal during aircraft flight.
WHY PITOT-STATIC SYSTEM CALIBRATION IS IMPORTANT
Due to the many running parts within a pitot-static system, it is of great importance to ensure that each part is functioning properly and accurately. Many devastating tragedies have occurred due to error of the pitot-static system. Airspeed and altitude are two key factors in safely operating an aircraft. In order to ensure overall safety of any individuals associated with an aircraft, calibration of the pitot-static system should be performed frequently. Calibration will ensure the pitot-static system is measuring total pressure precisely and accurately, which in turn will lead to correct readings of airspeed, altitude and altitude trends.
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