737 FCC
Thread Starter
Join Date: Jul 2006
Location: Norway
Age: 41
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
737 FCC
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
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
Join Date: Aug 2010
Location: VABB
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
The FCOM states that 'This independent F/D operation occurs when neither A/P is engaged in CMD'.
In the example you posted, you mentioned that the A/P is engaged so the LHS F/D is a slave of the RHS F/D.
In the example you posted, you mentioned that the A/P is engaged so the LHS F/D is a slave of the RHS F/D.
Thread Starter
Join Date: Jul 2006
Location: Norway
Age: 41
Posts: 122
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for answering, but I'm afraid you're mistaken. Tested it in the simulator today. Only the RHS has MASTER-indication, but the LHS is NOT slaved. Read my first note from the FCOM:
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.
So RHS show correct tracking, LHS shows an offset F/D. When A/P IS engaged I understand it's value, because you'd want to know what F/D-bars the A/P is following. On the other hand I'm not sure I get it if we were to have the same setup and the A/P's off.
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.
So RHS show correct tracking, LHS shows an offset F/D. When A/P IS engaged I understand it's value, because you'd want to know what F/D-bars the A/P is following. On the other hand I'm not sure I get it if we were to have the same setup and the A/P's off.
