
1) Aircraft instrument 2) Airspeed ratio indicator 3) Speed indicator 4) Speedometer
Found on
https://www.crosswordclues.com/clue/machmeter

A Machmeter is an aircraft pitot-static system flight instrument that shows the ratio of the true airspeed to the speed of sound, a dimensionless quantity called Mach number. This is shown on a Machmeter as a decimal fraction. An aircraft flying at the speed of sound is flying at a Mach number of one, expressed as Mach 1. ==Use== As an aircraft in...
Found on
http://en.wikipedia.org/wiki/Machmeter

(from the article `airspeed indicator`) ...differences and temperature give the true airspeed, which is used to calculate the aircraft`s position. In faster aircraft, indicators that ... ...that indicate power, such as the tachometer (in propeller craft), torquemeter (in turboprops), and exhaust pressure ratio indicator (in ... [2 re...
Found on
http://www.britannica.com/eb/a-z/m/4

[
n] - speedometer for measuring the speed of an aircraft relative to the speed of sound
Found on
http://www.webdictionary.co.uk/definition.php?query=machmeter
noun speedometer for measuring the speed of an aircraft relative to the speed of sound
Found on
https://www.encyclo.co.uk/local/20974
No exact match found.