Boeing (744/8) Localizer "sensing"
Hello,
B744/748.
Is there any prohibition or harm in arming the LOC prior to having "correct sensing" i.e. when the localizer pointer is still sensing in reverse due to the aircraft not yet tracking within 120 degrees of the localizer course? Example being a Localizer approach with a procedure turn: should/may you arm localizer prior to the inbound portion of the procedure turn?
As I understand it, the aircraft will not inadvertently capture the backcourse. The systems manual states "localizer capture can occur when intercept track angle is within 120 degrees of the localizer course".
Additionally, the FCTM states:
APP mode should not be selected until:
-The ILS is tuned and identified
-The aircraft is on an inbound intercept heading
-Both localizer and glideslope pointers appear on the attitude display in the proper position
-Clearance for the approach has been recieved.
Notice it says "APP" mode, not "LOC" mode, although logically the implications would be the same for the LOC mode.
My apologies if I missed this answer elsewhere in the manuals.
Personally I don't arm the LOC or approach modes until I have correct sensing as a matter of airmanship but I hesitate to tell others to do the same without a reference. I am attempting to build a case to dissuade people from premature LOC selection during a non-ILS, but maybe I'm wrong about this.
Thanks.
Last edited by RandomPerson8008; 9th Jun 2021 at 01:09.