Introduction of Flight Instruments

Aircraft became a practical means of transportation when accurate flight instruments freed the pilot from the necessity of maintaining visual contact with the ground. Safety was enhanced when all pilots with private or higher ratings were required to demonstrate their ability to maintain level flight and make safe turns without reference to the outside horizon.

The basic flight instruments required for operation under visual flight rules (VFR) are an airspeed indicator, an altimeter, and a magnetic direction indicator. In addition to these, operation under instrument flight rules (IFR) requires a gyroscopic rate-of-turn indicator, a slip-skid indicator, a sensitive altimeter adjustable for barometric pressure, a clock displaying hours, minutes, and seconds with a sweep-second pointer or digital presentation, a gyroscopic pitch-and-bank indicator (artificial horizon), and a gyroscopic direction indicator (directional gyro or equivalent).

Aircraft that are flown in instrument meteorological conditions (IMC) are equipped with instruments that provide attitude and direction reference, as well as radio navigation instruments that allow precision flight from takeoff to landing with limited or no outside visual reference.