While cockpit instrumentation can be represented by sophisticated electronic
flight management systems, virtually all aircraft have simple
mechanical instruments that work off atmospheric air pressure. Air pressure
is looked at in two ways. First the air pressures experience due to the forward
motion of the aircraft are sampled via the pitot, a tube that
senses the ram pressure of the air. The greater the airspeed, the
higher the pitot pressure. Air pressure of the atmosphere not related to the
forward movement of the aircraft is sampled by the static port,
which is generally located on the side of the aircraft. It is placed so that it
is least affected by the movement of the aircraft.