PDA

View Full Version : Fms true vs magnetic north


baobab72
30th Apr 2014, 17:21
Hi everyone
One question for the wizzards out there, even though it might look as silly!
Is the route/waypoint computed by the fms based on true or magnetic north?
The reason i am asking is that the coordinates definying a waypoint of the OTS can be entered either with the N for north prior to the coordinates or after the coordinates, resulting in a certain difference.
My guess is that if entered before the fms references the magnetic north while if after the true north.
I read the manual for the honeywell 6000 but i couldn t find anything along those lines.

Many thanks

Baobab

bucks_raj
30th Apr 2014, 18:26
I reckon

The Route is Magnetic
The Way point is True

Heard Bearing changes due Variations......
Ever Heard Waypoint changes due Variation...

A lot of the Avionics data is made by jepp's which never "publish" on the ENR True bearings b/w any points.

Ever Heard of magnetic co-ordinates of a Way point

BOAC
30th Apr 2014, 18:43
FMS's work on true north and correct for mag (or grid) if required by the customer. Where the 'N' is is irrelevant and depends on the way the FMS is programmed to accept data.

A waypoint's co-ordinates have no relevance to true or magnetic - it is a position only, not a bearing.