When do you press APPR pb RNAV (GNSS) APCH (AIRBUS)
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Hello Vilas,
This is a good thread, you have authored several very good posts.
At our company we do not arm APPR until with in 100' of the FAF altitude. "Once the aircraft is established in NAV or LOC and within 100 feet of the FAF altitude, the APPR button may be armed ...."
This has been explained to us because of anomalies in coding contained in our FMGC. This requirement does not pertain to -V approaches because of different coding. (Which may be a North America issue)
As others have posted, if APPR is armed prior to being within 100' of FAF altitude the airplane does "unusual" things.
Regards,
Mongo.
(Lexxie747 your comments are noted as is your retirement. I've instructed on T-37's and flown F-16's in combat, plumbed the 727 and co-piloted the 777, was a Captain on the Jurassic 737 and Captain on the A-320. True professionals learn their aircraft as well as honing their craft - enjoy your retirement, it is well deserved.)
This is a good thread, you have authored several very good posts.
At our company we do not arm APPR until with in 100' of the FAF altitude. "Once the aircraft is established in NAV or LOC and within 100 feet of the FAF altitude, the APPR button may be armed ...."
This has been explained to us because of anomalies in coding contained in our FMGC. This requirement does not pertain to -V approaches because of different coding. (Which may be a North America issue)
As others have posted, if APPR is armed prior to being within 100' of FAF altitude the airplane does "unusual" things.
Regards,
Mongo.
(Lexxie747 your comments are noted as is your retirement. I've instructed on T-37's and flown F-16's in combat, plumbed the 727 and co-piloted the 777, was a Captain on the Jurassic 737 and Captain on the A-320. True professionals learn their aircraft as well as honing their craft - enjoy your retirement, it is well deserved.)
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I seem to remember something in the logic on the RNP coded procedures, that APPR must be armed for the missed approach procedure to be available. I am not sure if this was on all variants, or has been fixed.
That may be why there is the differences noted in post #37 with VOR vs LNAV/VNAV...
That may be why there is the differences noted in post #37 with VOR vs LNAV/VNAV...
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Hello Vilas,
This is a good thread, you have authored several very good posts.
At our company we do not arm APPR until with in 100' of the FAF altitude. "Once the aircraft is established in NAV or LOC and within 100 feet of the FAF altitude, the APPR button may be armed ...."
This has been explained to us because of anomalies in coding contained in our FMGC. This requirement does not pertain to -V approaches because of different coding. (Which may be a North America issue)
As others have posted, if APPR is armed prior to being within 100' of FAF altitude the airplane does "unusual" things.
Regards,
Mongo.
(Lexxie747 your comments are noted as is your retirement. I've instructed on T-37's and flown F-16's in combat, plumbed the 727 and co-piloted the 777, was a Captain on the Jurassic 737 and Captain on the A-320. True professionals learn their aircraft as well as honing their craft - enjoy your retirement, it is well deserved.)
This is a good thread, you have authored several very good posts.
At our company we do not arm APPR until with in 100' of the FAF altitude. "Once the aircraft is established in NAV or LOC and within 100 feet of the FAF altitude, the APPR button may be armed ...."
This has been explained to us because of anomalies in coding contained in our FMGC. This requirement does not pertain to -V approaches because of different coding. (Which may be a North America issue)
As others have posted, if APPR is armed prior to being within 100' of FAF altitude the airplane does "unusual" things.
Regards,
Mongo.
(Lexxie747 your comments are noted as is your retirement. I've instructed on T-37's and flown F-16's in combat, plumbed the 727 and co-piloted the 777, was a Captain on the Jurassic 737 and Captain on the A-320. True professionals learn their aircraft as well as honing their craft - enjoy your retirement, it is well deserved.)
My point of view is different.Arming within 100 ft of the FAF gives you a temporary solution, but I don't think this is the philosophy of RNAV apchs. If the plane does unusual things, just take over and report it. If we all do it like this , the manufacturers, apch designers, etc will not correct and investigate; they may think the system is working good.
When do you arm the APPR for an ILS? I've got unusual G/S and LOC captures as well, but I still arm the apch when on intercept hdg of final track, with loc deviation available and I keep monitoring.If things don't go as expected, I take over and I report
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mi68guel
There is a power point presentation by Airbus Guide to Final Approach Mode. I think it was in 2011. whatever I stated was out of that. However "If the plane does unusual things, just take over and report." is the correct approach. I also have been an advocate of this. Especially FBW aircraft procedures should be designed by the manufacturer because they are the creators of the design philosophy and have the software, the hardware, wind tunnel and test pilots, mere FCOM just not good enough for that. Also they have global accident data base. What one airline wants to do may have already failed in another part of the world. At least airlines need to consult them about the changes envisaged. Arbitrary change of priority for monitoring of FMA in go around caused incidents in three airlines which could have easily been been accidents.
There is a power point presentation by Airbus Guide to Final Approach Mode. I think it was in 2011. whatever I stated was out of that. However "If the plane does unusual things, just take over and report." is the correct approach. I also have been an advocate of this. Especially FBW aircraft procedures should be designed by the manufacturer because they are the creators of the design philosophy and have the software, the hardware, wind tunnel and test pilots, mere FCOM just not good enough for that. Also they have global accident data base. What one airline wants to do may have already failed in another part of the world. At least airlines need to consult them about the changes envisaged. Arbitrary change of priority for monitoring of FMA in go around caused incidents in three airlines which could have easily been been accidents.
The aircraft tries to fly a geometric path projected backwards from the FAF altitude to the previous altitude constraint in the database. I have seen it try to climb up to meet it and then push over to maintain the path. I generally press the appr button within two miles of the faf but trying to be around the faf altitude.
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vilas, that is a great point. With the myriad of equipage possibilities and combinations of systems being used, it is very difficult to determine all of the possible issues that could occur. As noted many times, the Ge box and Honeywell box use completely different internal methodologies for location, especially in turns, and all are different than the procedure design software!
Prox warnings are another one, again with the different manufacturers using different values in the final segment. (HW 500' ROC and HW a 400' ROC at the FAF)
Had a hell of a time when one airline started using the RC system, it just could not understand fly-by waypoints and the constant descent profile, always porpoising down to a level segment after crossing the waypoint.
So, yes, please do report any anomoly, with as many parameters as possible that created the situation.
Prox warnings are another one, again with the different manufacturers using different values in the final segment. (HW 500' ROC and HW a 400' ROC at the FAF)
Had a hell of a time when one airline started using the RC system, it just could not understand fly-by waypoints and the constant descent profile, always porpoising down to a level segment after crossing the waypoint.
So, yes, please do report any anomoly, with as many parameters as possible that created the situation.
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At our company we do not arm APPR until with in 100' of the FAF altitude. "Once the aircraft is established in NAV or LOC and within 100 feet of the FAF altitude, the APPR button may be armed ...."
Last edited by mi68guel; 13th Jun 2016 at 05:36.
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What is the difference in lateral and vertical guidance if you push APPR pb before FAF Final altitude? There's no difference:
APP NAV and NAV : provide the same lateral guidance
DES (ALT FINAL): same vertical guidance as DES (ALT)
APP NAV and NAV : provide the same lateral guidance
DES (ALT FINAL): same vertical guidance as DES (ALT)
Last edited by mi68guel; 13th Jun 2016 at 05:38.
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I'm wondering how could you fly this approach to Queenstown, following your company procedures?
I am checking into this with the coding and the custom procedures. Especially the issue with the missed approach.
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Some confusion, your opinion?
You are 20 miles out, approaching the RNAV approach final course on an assigned heading.
Say it the XYZ RNAV RWY 360 and you are on your dogleg...
There are several step downs on the RNAV before the FAF, all coded in to the approach in the database and showing up on the ND. Life is great.
You are level at the altitude in managed NAV and it captures the course as it proceeds to the ABC waypoint directly ahead with its 8000+ constraint. The descent indicator (hockey stick) is WHITE, because you have 8000 feet still in the FCU.
You push APP pb in response to the controller starring "cleared the approach", you are a few miles from the ABC waypoint, you do not change the altitude in the FCU, still shows 8000 feet. Q: What color is the descent indicator (hockey stick) now? (your answer should be WHITE, but we have table top simulators that have it turning blue even with the FCU altitude set at current altitude)
What will happen at that descent point (you are approaching with a white hockey stick) with the aircraft if the APP is armed (pushed) showing on FMA : ALT (FINAL armed) and APP NAV? Will it revert to FINAL APP and descend as it crosses that white hockey stick every time - even with its FCU altitude window left at 8000...?
Our procedures are unique to many I'm reading here, curious the responses Im going to get...
Say it the XYZ RNAV RWY 360 and you are on your dogleg...
There are several step downs on the RNAV before the FAF, all coded in to the approach in the database and showing up on the ND. Life is great.
You are level at the altitude in managed NAV and it captures the course as it proceeds to the ABC waypoint directly ahead with its 8000+ constraint. The descent indicator (hockey stick) is WHITE, because you have 8000 feet still in the FCU.
You push APP pb in response to the controller starring "cleared the approach", you are a few miles from the ABC waypoint, you do not change the altitude in the FCU, still shows 8000 feet. Q: What color is the descent indicator (hockey stick) now? (your answer should be WHITE, but we have table top simulators that have it turning blue even with the FCU altitude set at current altitude)
What will happen at that descent point (you are approaching with a white hockey stick) with the aircraft if the APP is armed (pushed) showing on FMA : ALT (FINAL armed) and APP NAV? Will it revert to FINAL APP and descend as it crosses that white hockey stick every time - even with its FCU altitude window left at 8000...?
Our procedures are unique to many I'm reading here, curious the responses Im going to get...
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Not really an answer to your question, but I imagine you’ll find it interesting. You can push the approach push button when:1) cleared for the approach 2) the to waypoint is a final descent point (a point where you can find a coded FPA)
the change came about last year if I’m correct. PRO-NOR-SOP-18-C P 8/28
You're supposed to do a managed descent to the first final descent point altitude and then, when the FDP is the to waypoint, push approach P/b to get final app.
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You are 20 miles out, approaching the RNAV approach final course on an assigned heading.
Say it the XYZ RNAV RWY 360 and you are on your dogleg...
There are several step downs on the RNAV before the FAF, all coded in to the approach in the database and showing up on the ND. Life is great.
You are level at the altitude in managed NAV and it captures the course as it proceeds to the ABC waypoint directly ahead with its 8000+ constraint. The descent indicator (hockey stick) is WHITE, because you have 8000 feet still in the FCU.
You push APP pb in response to the controller starring "cleared the approach", you are a few miles from the ABC waypoint, you do not change the altitude in the FCU, still shows 8000 feet. Q: What color is the descent indicator (hockey stick) now? (your answer should be WHITE, but we have table top simulators that have it turning blue even with the FCU altitude set at current altitude)
What will happen at that descent point (you are approaching with a white hockey stick) with the aircraft if the APP is armed (pushed) showing on FMA : ALT (FINAL armed) and APP NAV? Will it revert to FINAL APP and descend as it crosses that white hockey stick every time - even with its FCU altitude window left at 8000...?
Our procedures are unique to many I'm reading here, curious the responses Im going to get...
Say it the XYZ RNAV RWY 360 and you are on your dogleg...
There are several step downs on the RNAV before the FAF, all coded in to the approach in the database and showing up on the ND. Life is great.
You are level at the altitude in managed NAV and it captures the course as it proceeds to the ABC waypoint directly ahead with its 8000+ constraint. The descent indicator (hockey stick) is WHITE, because you have 8000 feet still in the FCU.
You push APP pb in response to the controller starring "cleared the approach", you are a few miles from the ABC waypoint, you do not change the altitude in the FCU, still shows 8000 feet. Q: What color is the descent indicator (hockey stick) now? (your answer should be WHITE, but we have table top simulators that have it turning blue even with the FCU altitude set at current altitude)
What will happen at that descent point (you are approaching with a white hockey stick) with the aircraft if the APP is armed (pushed) showing on FMA : ALT (FINAL armed) and APP NAV? Will it revert to FINAL APP and descend as it crosses that white hockey stick every time - even with its FCU altitude window left at 8000...?
Our procedures are unique to many I'm reading here, curious the responses Im going to get...
the answer to your question is in DSC-22_30-80-30-20 "Engagement conditions".
It is normal that you get the final app activation at 8000 ft as you are within 150 ft of your constraint and within 1.5 nm left/right of track, provided all the other conditions are met.
