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Under Pressure
Properly Maintaining Pitot and Static Systems
by Elliott Cox
In the mid-18th century, French engineer Henri Pitot created a tube to measure the flow of water in the Seine River. German American inventor Paul Kollsman created the first accurate barometric altimeter in 1928.
Pitot and Kollsman were separated by over 200 years, but the work of these two men has shaped the world of aviation. Static pressure (Ps) is the pressure of the ambient air immediately surrounding an airplane and is measured by ports installed on both sides of the fuselage. Static ports connect outside air to the flight environment instruments and are placed in locations along the fuselage where the ambient air is unaffected by the speed, attitude or angle
of attack of the airplane.
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PHOTOS BY AUTHOR
Pitot pressure, also called total pressure (Pt), is sim- ply ram air forced into the pitot tube when an airplane moves through the air. The tube that Henri Pitot created in the 18th century closely resembles what we use in airplanes today to measure airflow. But what that tube connects to has evolved and been refined to produce an extremely accurate measurement of how fast we’re mov- ing through the air.
In older pitot/static systems, there were tubes and hoses that provided static and pitot pressure directly to analog flight environment instruments. The only electrical con- nections were for backlighting and an internal vibrator for the altimeter so it wouldn’t have to constantly be tapped