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 ?
Any error that can't be corrected is noted on a compass deviation card mounted on or near the compass.
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).
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.