Flight Instruments Chapter5 Introduction Aircraft became a practical means of transportation when  accurate flight instruments freed the pilot from the necessity  of maintaining visual contact with the ground. Flight  instruments are crucial to conducting safe flight operations  and it is important that the pilot have a basic understanding  of their operation. The basic flight instruments required  for operation under visual flight rules (VFR) are airspeed  indicator (ASI), altimeter, and magnetic direction indicator.  In addition to these, operation under instrument flight rules  (IFR) requires a gyroscopic rate-of-turn indicator, slip-skid  indicator, sensitive altimeter adjustable for barometric  pressure, clock displaying hours, minutes, and seconds with  a sweep-second pointer or digital presentation, gyroscopic  pitch-and-bank indicator (artificial horizon), and gyroscopic  direction indicator (directional gyro or equivalent).