A320 Final mode engagement conditions
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A320 "FINAL" mode engagement conditions
I found another confusing explanation as to the Final mode engaement conditions for non precision approaches.
Please, refer to FCOM vol. 1 1.22.30 on page 55(the page number might differ)
To quote the paragraph that has the problematic sentence:
Enagement conditions
APP NAV and NAV modes engage under the same conditions:
If NAV mode was engaged, APP NAV engages immediately. If HDG/TRK is engaged, APP NAV engages when the intercept conditions are met( aircraft track line must intercept the flight plan active leg).
FINAL mode engages, if:
-APPR phsed is active, and the deceleration point has sequenced, and
-APP NAV is engaged, and
-Cross track error is less than 1.5NM, and
-FINAL is armed, and
-The aircraft intercepts a descending leg of the vertical flight path, or
-In V/S (FPA) or OPEN DES, the aircraft intercepts a level-off segment of the vertical flight profile, with an FCU-selected altitude different from this level-off segment
What I do not understand is the red part; I just can't think of a situation that righfully reflect the circumstance which the red part tries to depict.
The only way to intercept the level-off segment--wherever the level-off segment may be located--in V/S or OPEN DES would be to push in V/S, FPA selector, which will engage FINAL mode according to FCOM, I presume? I konw that this barely happens in real world but Any A320 jockeys please, help.
Please, refer to FCOM vol. 1 1.22.30 on page 55(the page number might differ)
To quote the paragraph that has the problematic sentence:
Enagement conditions
APP NAV and NAV modes engage under the same conditions:
If NAV mode was engaged, APP NAV engages immediately. If HDG/TRK is engaged, APP NAV engages when the intercept conditions are met( aircraft track line must intercept the flight plan active leg).
FINAL mode engages, if:
-APPR phsed is active, and the deceleration point has sequenced, and
-APP NAV is engaged, and
-Cross track error is less than 1.5NM, and
-FINAL is armed, and
-The aircraft intercepts a descending leg of the vertical flight path, or
-In V/S (FPA) or OPEN DES, the aircraft intercepts a level-off segment of the vertical flight profile, with an FCU-selected altitude different from this level-off segment
What I do not understand is the red part; I just can't think of a situation that righfully reflect the circumstance which the red part tries to depict.
The only way to intercept the level-off segment--wherever the level-off segment may be located--in V/S or OPEN DES would be to push in V/S, FPA selector, which will engage FINAL mode according to FCOM, I presume? I konw that this barely happens in real world but Any A320 jockeys please, help.
Last edited by simyoke; 1st Sep 2008 at 05:01.
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I may be interpreting this wrong, but isn't what they are describing, is the procedure for capturing the glide path from above?
1. Set altitude above your current height.
2. Dial in V/S 1600 FPM down or by selecting speed 180 KTS in OPEN DES.
1. Set altitude above your current height.
2. Dial in V/S 1600 FPM down or by selecting speed 180 KTS in OPEN DES.
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How to intercept the level-off segment
Thank you very much for the reply.
So if the glide path (or I would rather call a descent profile )(for a non precision approach in this case) is to be intercepted with the FCU altitude set at an altitude that differs from that of the level-off segment ,the only way to level-off would be pushing the V/S/FPA selector knob, right? So according to FCOM, the moment the V/S,FPA selector knob is pushed in, Final mode engages?
So if the glide path (or I would rather call a descent profile )(for a non precision approach in this case) is to be intercepted with the FCU altitude set at an altitude that differs from that of the level-off segment ,the only way to level-off would be pushing the V/S/FPA selector knob, right? So according to FCOM, the moment the V/S,FPA selector knob is pushed in, Final mode engages?
Last edited by simyoke; 30th Aug 2008 at 00:22.
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as to the level-off segment
By reading FCOMs, I assume the usual procedure would be to use managed mode for both vertical and lateral guidance. The point FINAL mode usually engages is when the aircraft passes the final approach fix after which only one stable descent path is defined by a flight path angle set at around -3 degrees. I am not sure what this "level-off segment of the vertical flight profile" means. Is this level off segement is the one that follows the final approach fix before the missed approach point?
