Hello colleagues
I have a question regarding the 737 FCC. Here goes:
RHS FCC is master and A/P is connected. If HDG bug is turned, both F/D roll bars turn towards new heading. Fair enough.
Next, RHS FCC is master and A/P is connected. RHS VHF panel has a localizer frequency selected and crs selector set to an inbound course. VORLOC is selected on the MCP.
LHS VHF panel has a VOR frequency selected and CRS selector set to a 20 degree offset course from the localizer.
Ok, the A/P will follow the localizer track, but the LHS F/D will show an offset, right? Even though RHS FCC is still master.
The FCOM states:
Rotate Captain’s course selector – provides selected course information to:
• A FCC
• No. 1 VHF NAV receiver
• Captain’s course pointer and course deviation bar.
Note: In VOR LOC or APP mode, the A A/P and Captain’s F/D use selected
course and navigation data from the No. 1 VHF NAV receiver.
Rotate First Officer’s course selector – provides selected course information to:
• B FCC
• No. 2 VHF NAV receiver
• First Officer’s course pointer and course deviation bar.
Note: In VOR LOC or APP mode, B A/P and First Officer’s F/D use selected
course and navigation data from No. 2 VHF NAV receiver.
It also states:
F/D modes are controlled directly from the respective FCC under certain
conditions. This independent F/D operation occurs when neither A/P is engaged
in CMD, both F/D switches are ON and one of the following mode conditions
exists:
• APP mode engaged with LOC and G/S captured
• GA mode engaged and below 400 feet RA
• TO mode engaged and below 400 feet RA.
Independent F/D operation is indicated by illumination of both MA lights. When
independent operation terminates, the MA light extinguishes on the slaved side.
So my question is: Why at all have a master FCC in F/D - operation at all? In situations where it seems we may have differing inputs on the left or right hand side (VORLOC/APP mode), the master function is from what I understand not applicable.
I may be way off here, but any input is very welcome. Thanks
