MDA on FCU in A320
Beau_Peep
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MDA on FCU in A320
I just noticed a recent change in limitations of A320.
the AP or FD in OP DES/DES mode can be used in approach if FCU altitude is set to or above, the higher of : MDA or 500ft agl
I always believed that MDA can't be set on FCU. but looks like airbus has no objection in doing so..
Any thoughts about it?
the AP or FD in OP DES/DES mode can be used in approach if FCU altitude is set to or above, the higher of : MDA or 500ft agl
I always believed that MDA can't be set on FCU. but looks like airbus has no objection in doing so..
Any thoughts about it?
Only half a speed-brake
Does not sound like a change to me either. Besides, what they say is that it must not be set below MDA, not that it is a suggested operating technique to do so.
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This is not new change in limitation. It was there in FCOM from 18Mar 2011. The use of OP DES/DES upto 500ft is a limitation of the AP/FD equipment. Setting MA on the FCU is the recommended procedure for the NPA.The reason for that is not the limitation but the nature of OP DES mode where it maintains the speed and not the flight path. With terrain clearance issue FPA or VS mode is safer option.
Last edited by vilas; 21st Oct 2017 at 03:32.
Beau_Peep
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This is not new change in limitation. It was there in FCOM from 18Mar 2011. The use of OP DES/DES upto 500ft is a limitation of the AP/FD equipment. Setting minima on the FCU is the recommended procedure for the NPA.The reason for that is not the limitation but the nature of op Des mode where it maintains the speed and not the flight path. With terrain clearance issue FPA or VS mode is safer option.
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Sorry! I meant Setting MA on the FCU. I corrected the post. Also if you set minimums then aircraft will flare out to level and the minimums will be reached further away closer to the runway.
Last edited by vilas; 21st Oct 2017 at 04:44.
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The previous FCOM minimum height for autopilot use were:
Straight-in non precision approach.....applicable MDA (MDH)
Straight-in LNAV/VNAV approach.......applicable DA
Circling Approach............................applicable DA -100ft
Airbus has recently completed re-certification, and the new limitations are as follows:
Non precision approach using F-LOC or F-G/S.....200' AGL
Non precision approach using FINAL APP,
NAV FPA, NAV V/S, TRK FPA or HDG/VS.............200' AGL
Circling Approach............................................500' AGL
The new limitations allow for greater flexibility on approaches with high minima and on RNAV (RNP) approaches with radius to fix legs at low altitude. Go Around with AP is now also available below minima. In essence, there is now a decorrelation between AP/FD disconnection and the decision to continue.
However, there is a caveat: AP/FD may be kept on below minima, if there are sufficient visual references, and ONLY IF guidance is fully managed, using one of the following modes: APP DES, FINAL APP, F-LOC or F-G/S. AP may therefore logically not be used below minima using NAV or TRK FPA.
It is for this reason the note regarding setting of the FCU altitude at or above the higher of the two: MDA/MDH or 500' AGL. Since this is only applicable to guidance other than fully managed, your company may have to amend procedures for non-precision approaches under these circumstances.
Below minima, visual reference remains the primary reference.
If you want more info, drop me a PM, and I'll forward you a pdf version of a slideshow presented by Airbus on the topic at the last Operations and Training seminar
Straight-in non precision approach.....applicable MDA (MDH)
Straight-in LNAV/VNAV approach.......applicable DA
Circling Approach............................applicable DA -100ft
Airbus has recently completed re-certification, and the new limitations are as follows:
Non precision approach using F-LOC or F-G/S.....200' AGL
Non precision approach using FINAL APP,
NAV FPA, NAV V/S, TRK FPA or HDG/VS.............200' AGL
Circling Approach............................................500' AGL
The new limitations allow for greater flexibility on approaches with high minima and on RNAV (RNP) approaches with radius to fix legs at low altitude. Go Around with AP is now also available below minima. In essence, there is now a decorrelation between AP/FD disconnection and the decision to continue.
However, there is a caveat: AP/FD may be kept on below minima, if there are sufficient visual references, and ONLY IF guidance is fully managed, using one of the following modes: APP DES, FINAL APP, F-LOC or F-G/S. AP may therefore logically not be used below minima using NAV or TRK FPA.
It is for this reason the note regarding setting of the FCU altitude at or above the higher of the two: MDA/MDH or 500' AGL. Since this is only applicable to guidance other than fully managed, your company may have to amend procedures for non-precision approaches under these circumstances.
Below minima, visual reference remains the primary reference.
If you want more info, drop me a PM, and I'll forward you a pdf version of a slideshow presented by Airbus on the topic at the last Operations and Training seminar
Last edited by reptile; 21st Oct 2017 at 05:18.