B747-400 Standby RMI Flags In TRUE HDG
Hi, folks
I noticed a few weeks ago on an Atlas 744 Freighter that when I selected the Magnetic Heading Reference switch to TRUE heading (from NORM), that the VOR and compass flags dropped into view on their single RMI. At the time, I assumed this was normal.
Last week, I read in their maintenance manual that the RMI uses both MAG and TRUE (a few other airline's AMMs also specified this, but haven't had the chance to confirm it on their aircraft).
The AOM doesn't go into much detail on this issue and the wiring schematics don't help.
What happens on your RMI-equipped 744's? (BA? TG? etc) Is it an option to have the RMI operate in TRU?
Perhaps the RMI only uses True Hdg if the switchover to TRU is automatic (at high latitudes)?
Thanks.
Cheers.
NSEU
P.S. I hear that Thule in Greenland has a VOR which uses TRU reference, so there is no reason why RMI's won't work at high latitudes (The FMC doesn't like it for position updating, however, according to one bulletin).
Last edited by NSEU; 22nd May 2010 at 02:07.