A320 NPA question
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Hello everyone !
I'm thinking this way: green dot at 3000 till D7 from KFA. Here S speed, CONF1, then CONF2. According to the depicted 3.05° profile we should commence the descent at say 3.6 NM from KFA (3000-1900= 1100ft at 300 ft/nm), but adding up 0.3 NM (allowing for AP reaction in FPA mode) so just opted for 4NM before. Starting a continuous descent at D4 KFA we're supposed to cross the VOR at 1900 with LDG gear down/CONF 3. CONF FULL comes at say D1 KFA / 1600 FT.
Guess a constant 700 fpm V/S may be kept throughout the final approach ...
I'm thinking this way: green dot at 3000 till D7 from KFA. Here S speed, CONF1, then CONF2. According to the depicted 3.05° profile we should commence the descent at say 3.6 NM from KFA (3000-1900= 1100ft at 300 ft/nm), but adding up 0.3 NM (allowing for AP reaction in FPA mode) so just opted for 4NM before. Starting a continuous descent at D4 KFA we're supposed to cross the VOR at 1900 with LDG gear down/CONF 3. CONF FULL comes at say D1 KFA / 1600 FT.
Guess a constant 700 fpm V/S may be kept throughout the final approach ...
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Depends on company SOP.
For selected NPA we have a stabilised approach criteria, have to be at config full, gear down, S speed before we commence descent. We're taught the 7 5 3 2 1 nm before descent point to do configuration changes.Then a continous descent to MAP or MDH, unless visual. Dive and drive is not permitted with us as the big thrust changes would destabalise the approach.
Otherwise what you propose seems eminently practical. Just keep in mind the altimeter errors due to high OAT, and make sure you cross the beacon not below the 1900' published check height.
Such a lot of debate on what seems to be a very straight forward question.
For selected NPA we have a stabilised approach criteria, have to be at config full, gear down, S speed before we commence descent. We're taught the 7 5 3 2 1 nm before descent point to do configuration changes.Then a continous descent to MAP or MDH, unless visual. Dive and drive is not permitted with us as the big thrust changes would destabalise the approach.
Otherwise what you propose seems eminently practical. Just keep in mind the altimeter errors due to high OAT, and make sure you cross the beacon not below the 1900' published check height.
Such a lot of debate on what seems to be a very straight forward question.
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Hello
Have you guys taken into account the fact that the VOR, and hence the DME is not near the runway threshold?
slant ranges and horizontal distances differ a lot near the VOR!
maybe not much in this case, as I see now, but can have an effect.
Can any one of you, folks, paste here a graph of that chart by EAG, instead of jeppesen. They provide you with the altitude, DME table. It would be enlightening.
They work just fine, I can't understand why they deprive us from that info in jeppsen's.
Have you guys taken into account the fact that the VOR, and hence the DME is not near the runway threshold?
slant ranges and horizontal distances differ a lot near the VOR!
maybe not much in this case, as I see now, but can have an effect.
Can any one of you, folks, paste here a graph of that chart by EAG, instead of jeppesen. They provide you with the altitude, DME table. It would be enlightening.
They work just fine, I can't understand why they deprive us from that info in jeppsen's.
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stm44ae
I am curious about this - can you write the exact words in the Ops Manual/memo from chief pilot/whatever?
And I must be getting old - what is THC?
The approach does not "commence" until the FAF - all that goes before is just positioning and terrain clearance.
And what do you set in the FCU ALT before the FAF/VOR? 1900' risks destabilising your carefully calculated approach by ALT* just when you want to be descending... but is the only way of ensuring you do not go below it unwittingly.
I would fly it as drawn - simpler, quicker and less fuel used.
our company dont allow us to used stepped profile they want me to start descending from 3000 to THC
And I must be getting old - what is THC?
The approach does not "commence" until the FAF - all that goes before is just positioning and terrain clearance.
And what do you set in the FCU ALT before the FAF/VOR? 1900' risks destabilising your carefully calculated approach by ALT* just when you want to be descending... but is the only way of ensuring you do not go below it unwittingly.
I would fly it as drawn - simpler, quicker and less fuel used.
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I'm even more curious now, from the dialogue it would appear that there is a suggestion from some that you draw a CDFA from 3000 platform turn to the 50 ft TCH? What happened to the concept of MDA, 560 ft in this case, so surely, the NPA " Glide" must be constructed to cross the MDA point at the correct DME and not at the TCH.
I am aware that no one flys a level flight segment.
By my simple maths, 3000 -560= 2440 at 3 degrees CDFA , just over 8 miles, this will put you at MDA about 1 mile from the VOR inbound, which is far too far out, hence the profile as drawn.
Surely a CDFA would need the first descent from 3000 to 1900 at about 1.5 degrees ( 1100 ft loss over 7 miles) the second descent is then at 3.05 degrees, 1900 to 560 ft
In operational terms, that just means increasing the rate from 1.5 to 3 degrees at a point 0.3 DME from the VOR inbound ( 5.3 DME)
I am aware that no one flys a level flight segment.
By my simple maths, 3000 -560= 2440 at 3 degrees CDFA , just over 8 miles, this will put you at MDA about 1 mile from the VOR inbound, which is far too far out, hence the profile as drawn.
Surely a CDFA would need the first descent from 3000 to 1900 at about 1.5 degrees ( 1100 ft loss over 7 miles) the second descent is then at 3.05 degrees, 1900 to 560 ft
In operational terms, that just means increasing the rate from 1.5 to 3 degrees at a point 0.3 DME from the VOR inbound ( 5.3 DME)
Last edited by Kirks gusset; 25th Feb 2010 at 21:06.
Only half a speed-brake
TDZE 56 + TCH 50 = 106 ft
MDA = 560
MDA - TCH = 454 ft
So to arrive over THR at 50 ft on a stable 3,02 deg profile (330 ft/NM) this will see you cross the MDA at 454/330 = 1,38 NM before THR a.k.a 5,5-1,38 = 4,12 NM after VOR. This is quite consistent with the DME table showing 610 ft at 4 DME (slant range, as correctly pointed out by Micro02). Correct?
Yours,
FD (the un-real)
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Folks
You fly the approach to be at MDA at the correct DME! In this case 5.0 DME from the VOR, a 3 deg profile works, use it, if possible?
Then when visual, you fly visually/PAPI to land the aircraft. If not visual you go around.
Flying is simple! Keep it that way and there is less chance you’ll miss the big picture!
You fly the approach to be at MDA at the correct DME! In this case 5.0 DME from the VOR, a 3 deg profile works, use it, if possible?
Then when visual, you fly visually/PAPI to land the aircraft. If not visual you go around.
Flying is simple! Keep it that way and there is less chance you’ll miss the big picture!
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Hi 68+,
If you follow the published descent profile, you'll be at your MDA before 5 DME. The missed approach point (MAP) is at 5 DME.
The original question was simply asking at what DME from the VOR could you leave 3000 feet on a 3.05 deg to satisfy all the altitude checks.
3000 - 1900 = 1100 feet. At 320 feet per mile; descend at 3.4 DME.
If you follow the published descent profile, you'll be at your MDA before 5 DME. The missed approach point (MAP) is at 5 DME.
The original question was simply asking at what DME from the VOR could you leave 3000 feet on a 3.05 deg to satisfy all the altitude checks.
3000 - 1900 = 1100 feet. At 320 feet per mile; descend at 3.4 DME.
Last edited by rudderrudderrat; 26th Feb 2010 at 18:40.
