TABLE OF CONTENTS An accurate measurement of airspeed and altitude is necessary for safe flying. This is especially true for flight testing. In addition to the error caused by the airplane's instruments, several other errors are associated with the pitot-static system. This chapter will discuss these errors, the methods for evaluating them, and the requirements for calibration and accuracy as defined in the Federal Aviation Regulations.
The FAA and its predecessors have always considered flight instrument accuracy to be important. Aeronautics Bulletin 7-A states: "The 'indicated' airspeed is defined as the speed which would be indicated by a perfect airspeed indicator, namely one which would indicate true air-speed at sea level under standard atmospheric conditions." It further refers the reader to Aeronautics Bulletin 26, section 6(A)(8), for further information on airspeed indicators. Current regulations require accuracies over specified ranges of airspeed and altitude.
This regulation requires the airspeed indication system to be so installed as to indicate true airspeed at sea level (calibrated airspeed) under standard conditions within an allowable installation error of no more than 3% of the calibrated airspeed or 5 statute mph, whichever is greater, between 1.3 V S 1 and V C with the flaps up and at 1.3 V S 1flaps down. The regulation requires the calibration to be made in flight.
This regulation states that airplane speed, the opening...
