Altitude constraint
Hi.
Why when I use VNAV descent it doesn't respect constraint altitude?
I must to use VS to descent more quickly when I arrive at my altitude constraint.
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Hi.
Why when I use VNAV descent it doesn't respect constraint altitude?
I must to use VS to descent more quickly when I arrive at my altitude constraint.
Comments
Hello, please say specifically which airport, which SID / STAR and a picture of the corresponding F / PLN page
Hi,
It took me quite a while to figure out what was the problem as you were not giving enough information.
I understand you are going to KLIT where there are no STARs and ALMOW is the IAF for Rwy 18.
VS 1600 Ft/mn is not a problem at all as your GS looks around 270 Kt. But your GS could change quite a bit in the next 700 Nm.
Anyway, what you should do is to be stable (landing flaps and gear down) before reaching ALMOW and to do so decelerate to be level quite few Nm before ALMOW (say 7 Nm).
Then you sould have enough time to decelerate and reprogram your VNAV approach to KLIT.
JP
I figured out i must to divide G/S by 2 to get my V/S to descent.
flight plan:EGLL to LFPG
sid:MAXI1F
star:BIBA9E
as you can see i must to be LORNI for 7000 feet .
VNAV profile ok.
Im at 15300 feet and im almost to arrive.
But you should have had 10,000 ft in KOLIV, 8,000 ft in NOPAR. You have already missed these restrictions with currently 15,000 ft. How did you program the VNAV?
Hi,
The first thing is to have your STAR right.
Coming from EGLL you arrive BIBAX 9E which is correct but after you should select the correct transition: MOPAR 6E, not LORNI which is to be used only when you arrive from the North East or the East.
Usually you should be by FL100 at KOLIV when East configuration and FL110 when West config. You'll probably land on Rwy 09L.
You should have selected, when programming VNAV, to be 10000 by KOLIV, then MOPAR.
When you land CDG (real world) you are vectored by ATC so to have it as near as the real thing the best way would be to follow the LOST COMS procedure as described on the chart.
JP
My VNAV set up is for the waypoint FF27L 5000 feet.
1500 V/S.
Are you executing the proper procedure to have VNAV capture the constraints correctly? This is what those who are trying to help are asking.
While we are all here to help, there has to be some input on the user to acquire some of the valid information required.
I can recommend you to a good source written by MudSpike (no affiliation with Majestic Software) which has been very helpful to many. You want to have look at Chater 10 - Approach and Landing.
https://www.mudspike.com/wp-content/uploads/2019/01/P3D-Majestic-Q400-Guide.pdf
Cheers
Hi
From EGLL to LFPG the arrival is always through BIBAX. So far, so good.
The landing Rwy should be 27R
BIBAX 9E that you are using is only for East landings. You should use BIBAX 9W. It is in theory used only by Jet planes but suitable for the Q400 due to her performances.
Then the transition is MOPAR 6W. You should not go to LORNI. Plan to be at MOPAR at FL110.
The Jeppesen charts: 20-2L / 21-OA08 / 21-8.
As mentioned in my previous post as we do not have radar vectors with the sim, follow the LOST COM.
If you follow exactly the procedure it should go fine.
JP
normally me I would use FF27R 5000 feet.
Your first constraint is KOLIV FL130, then MOPAR FL110.
You set up your VNAV 11000 and your ALT (no need for ALT SEL) 11000.
You'll need to be level by GIZOQ 5000' so you set VNAV 5000 and your ALT 5000 and also ALT SEL to make sure you level at 5000'.
You do not use FF27R which is your TOD for the ILS 27R.
When you turn right on track 238° you switch from PINK to BLUE, HDG SEL 238° and arm APPR to intercept LOC and GLIDE.
Plane not suppose respect all altitude constraint ?
Constraints:
KOLIV FL130
MOPAR FL110
GIZOQ 5000'
After GIZOQ you are on the ILS Loc and you are going to intercept the glide at FF27R so to make it simple, after GIZOQ forget about LNAV/VNAV and follow the ILS (BLUE instead of PINK).
Real life could be a bit different as you would be cleared direct KOLIV or MOPAR FL110 and radar vectors with altitude and speed given by ATC until you intercept the ILS. So with radar you do not work LNAV/VNAV but HDG, ALT with ALT SEL.
If you set your VNAV MOPAR 11000 it would respect KOLIV 13000 and would level 11000 at MOPAR.
Then you set GIZOQ 5000 and it would level 5000 by GIZOQ.
To make sure to be perfectly stabilized in altitude and speed at GIZOQ, you can enter few Nm before the WP as I explained in my previous post regarding KLIT.
On the charts and in the FMS the altitudes are clearly marked.
Forget about FF27R. This WP is after GIZOQ and you have to be at 5000 at GIZOQ.
Sorry But why I can't set FF27R and if I set FF27R why plane don't respect all altitude constraint before ?
Due to the different time zones, the discussions always take place when you can't yourself ;-)
Assume that ATC will bring you down on time and in compliance with the restrictions that they are also aware of. I myself always enter the first height restriction for calculating the TOD, as this must be observed first and then I am "Ready for Descend" a good 50 NM beforehand, in order to be able to descend flexibly. The descent using VNAV then takes into account all other restrictions, you just have to pre-select the altitude accordingly in the MCP. So theoretically you can sink down to the final approach, only VNAV will briefly disconnect before the FAF (depends on certain circumstances) in order to get a defined, new confirmation of the VNAV mode for sinking in the final.
You don't have to / can't always go down with VNAV, as ATC often messes up our profile. So it will be necessary to switch to VS somewhere, because we have to stay at a certain height for too long or have been assigned an intermediate height that is not known in the VNAV profile. In many cases, vectors in the vicinity of the airport mean that you have to change the modes of the autopilot system.
Because FF27R is not a constraint. It is the start of the glide for the ILS.
You should do it the way described if you want to do it as near as the real thing otherwise I do not think it would work and you are going to be disappointed by the results especially if you intercept a false glideslope.
ILS are flown that way: LOC intercepted, on centerline, altitude stable in level (5000' ILS 27R CDG) before to intercept the glide with the flaps and gear and that has been done that way long ago before the FMS existed.
Sorry, I did not see FraPre comments when I posted.
No, you program (or I'll do it that way) VNAV based on the first restriction in the flight path. VNAV remains active and only levels where the height set on the MCP is reached. If you pretend (offline) that you always get the next altitude cleared in time, you turn in the next altitude in a timely manner and the aircraft continues to sink using VNAV, also taking into account the next altitude. Only before the FAF (Final Approach Fix), i.e. at the beginning of the Final Approach, VNAV is automatically deactivated, since the autopilot system really wants to ensure that you go to the final with VNAV. Here you simply activate VNAV on the MCP again. I have to see if I can get a series of photos banned into a PDF without exceeding the data size.