compass deviation

compass deviation

[′käm·pəs ‚dēv·ē′ā·shən]
(navigation)
The difference between the readings of a compass which is without mechanical defects and is held motionless in space, and the same instrument when it is installed in the same geographic position but is mounted on a ship or aircraft; deviation is a systematic error which is compensated by placing iron bars in places about the compass; residual deviation errors are calibrated and noted on a card so it can be used by the pilot or navigator.
References in periodicals archive ?
For example, the inspecting technician should examine it to ensure there's a compass deviation card present (and perhaps review logbook entries to see if the compass has been swung since any avionics or electrical work).
(A thermometric calibration system based on absolute zero is called the Kelvin scale.) His purchase of a yacht, in 1870, meant not only boating pleasure but a new range of scientific questions to investigate, particularly the compass deviations caused by the ever-increasing amounts of iron used in ship construction.