Editing Variometer (section)

==Electronic variometers==
In 1954, MacCready pointed out the advantages of an Audio Variometer, "There is much to be gained if the variometer indication is presented to the pilot by sound. More than any other instrument except during blind flying, the variometer must be watched continuously. if the pilot can get the reading by ear, he can improve his thermal flying by watching nearby gliders, and he can materially improve the overall flight by studying the cloud formations to be used next."<ref name=pm/>

In modern gliders, most electronic variometers generate a sound whose pitch and rhythm depends on the instrument reading.  Typically the audio tone increases in frequency as the variometer shows a higher rate of climb and decreases in frequency towards a deep groan as the variometer shows a faster rate of descent.  When the variometer is showing a climb, the tone is often chopped and the rate of chopping may be increased as the climb rate increases, while during a descent the tone is not chopped.  The vario is typically silent in still air or in lift which is weaker than the typical sink rate of the glider at [[Polar curve (aviation)|minimum sink]]. This audio signal allows the pilot to concentrate on the external view instead of having to watch the instruments, thus improving safety and also giving the pilot more opportunity to search for promising looking clouds and other signs of lift. A variometer that produces this type of audible tone is known as an "audio variometer".

Advanced electronic variometers in gliders can present other information to the pilot from  [[global positioning system|GPS]] receivers.  The display can thus show the bearing, distance and height required to reach an objective.  In cruise mode (used in straight flight), the vario can also give an audible indication of the correct speed to fly depending on whether the air is rising or sinking.  The pilot merely has to input the estimated [[Paul MacCready|MacCready]] setting, which is the expected rate of climb in the next acceptable thermal.

There is an increasing trend for advanced variometers in gliders towards flight computers (with variometer indications) which can also present information such as controlled airspace, lists of turnpoints and even collision warnings.  Some will also store positional GPS data during the flight for later analysis.