NG FMC: Alternate airports

[Hardy Heinlin]

Good morning, hazy mysterious world,

on the XXXX ALTN page in 5L there is a toggle key for <ALL ENG and <ENG OUT.

Honeywell says: "Pushing 5L returns engine out information to all engine information."
Boeing says: "This prompt performs the same function as described on the cruise page."

I know what this function does on the CRZ page: Among other things, it changes the route status from ACT to MOD. It may also lower the current CRZ ALT for E/O conditions.

If I perform this function while in ALL ENG mode, I can only undo it by pushing the ERASE key.

But toggling 5L on the XXXX ALTN page from <ENG OUT to <ALL ENG certainly won't ERASE the current MOD.

This makes no sense.
Perhaps it's just an "arming" function that may activate the E/O mode when I push DIVERT NOW>?
(5L is blank when DIVERT NOW is selected and not executed yet.)

If I read Honeywell's cryptic description, I guess pushing 5L won't change the status from ACT to MOD but it just changes the performance conditions for the ETA/fuel calculations on the ALTN pages.

But then the line title should indicate the current mode, e.g. like this:

all eng mode
<ENG OUT

eng out mode
<ALL ENG


Regards,

|-|ardy

[Hardy Heinlin]

OK, I think it works like this:

<ENG OUT is displayed in 5L when VNAV is in ACT all-engine mode. Pushing 5L changes VNAV to MOD E/O and 5L blanks, and <ERASE replaces <ALTN in 6L.

<ALL ENG is displayed in 5L when VNAV is in ACT E/O mode. Pushing 5L changes VNAV to MOD all-engines and 5L blanks, and <ERASE replaces <ALTN in 6L.


And, having seen 767 and 744 NG in action now, here's another theory for the INHIB pair:

Entering a slashless XXXX into ----/---- will make this: ----/XXXX
Entering a slashless YYYY into ----/XXXX will make this: YYYY/XXXX
Entering a slashless ZZZZ into YYYY/XXXX will make this: ZZZZ/XXXX

I.e. it only goes to the left side when an entry exists on the right side. (Some CBTs seem to differ from the real FMC in this respect.)


|-|

[Hardy Heinlin]

I.e. it only goes to the left side when an entry exists on the right side.

Now having seen it going to the right side on a 767 FMC, this function might depend on:
• the FMC version
• the alphabetic order
• a random generator
• odd/even weekdays
• ...

[Hardy Heinlin]

Regarding the <ENG OUT prompt again, on the ALTN page:

When in ACT DES, the CLB and CRZ pages don't show any <ENG OUT prompt anymore.

So I think in ACT DES this prompt should be blank on the ALTN page as well.


|-|ardy

[Mariano]

Hardy,

I sent you an email. In case you haven’t received it (like the one yesterday), please let me know.

Best regards,

Mariano

[Hardy Heinlin]

Got it, Mariano. Thank you!

I see the <ENG OUT prompt remains displayed on the ALTN page when in ACT DES.


Cheers,

|-|ardy