1.1.3 Impossible to perform ILS Approaches

[frmdes]

Hello guys,

I'm testing the 1.1.3 version and it is much better than the previous versions, congratulations.

But unfortunately i'm having a lot of trouble trying to perform any Brazil (where i'm from) ILS approaches.
The VNAV function works very well performing SIDs and STARS, obeying all the altitude contraints, but when i reach the IAF intersection and when i am about to start the approach phase, the problems starts to appear.

Let's have this example:

SBCT (curitiba airport), ILS-W RWY 15 Approach (chart attached)

When i'm over the IAF position, (SOVTA or DODRA intersection), i set the preselector to the MDA altitude, allowing the VNAV starts the descend (before TOD). The VNAV is obviusly engaged. The aircraft starts to descend to the next altitude constraint (in this case, 5500ft TEDUG intersection). The problem is, the aircraft always cross over the intersection about 1000ft above it should to cross (about 6500ft). The same thing will happen to the next intersection that follows.
Untill now, i can disable the VNAV, set VS to the lower altitude before glideslope (in this ILS approach, 4600ft), but again there's another problem. When i hit the APPR button, the LOC 1 APPR is changing ok, i see the purple diamond decreasing, and when it reaches the middle position in the bar, the aircraft do not start to descend, or sometimes it climbs, instead of descending, or sometimes it starts to nose diving, making me crash if i dont quickly disengage the AP.
I made an example using this chart attached, but you can perform SBFL ILS-Y RWY 14, or SBBR ILS-Y or ILS-Z (RWYs 11L and 11R) or probably any ILS procedures that we perform in Brazil, and the aircraft behaves the same way. I always keep my eye in the speed, and i don't let it drops below 140 knots untill i reach 1 nm before final, when i start to decrease the trottle.

I hope you can help me to solve this, maybe i'm doing something wrong, or maybe it's a bug, i don't know, but i will keep trying and reading the FMS-3000 and proline 21 manuals.

Regards,
Felipe Mendes.

[Taguilo]

Hi,

Thanks for the info. I tested your case and found an issue; it's already fixed and available for the SP.

Thanks again.

Tomas

[frmdes]

Thats good to hear, thanks!

Another bug i just found, again in the approach phase, happens if i press the ALT button (to level off the aircraft) in the middle of the process of descending. That bug doesn't happen all the time, but the PFD upper display gets crazy, changing the VNAV paths undefinitly, unless i disengage the AP and engage again. I will try to make a video and upload for you.

Please check this out.

Regards,
Felipe Mendes.

[Heronjr]

Oi Felipe,

I am from Rio and happy to meet a neighbor in this forum. I have been testing this KA since the first version 5 years ago and I can say now, it is almost done. I started to fly the last (good) releases early last year, intending a full round the world with the KA starting from Ushuaia (Argentina). Now I am crossing the Quebec Province (Canada), preparing to attack Greenland and Iceland to reach Europe.

As you might conclude, in this trip I've experienced many types of approaches, and some of them with the same problem you had in the SBCT ILS-W 15. During this time, the Milviz crew fixed bugs and tuned the nav systems at a point we should today trust 90% the RNAV behavior. Some we descend perfectly, like an ILS, but others we have to hold the horse ourselves, otherwise crash!

One thing that is very important on ILS approaches, is that sometimes the frequencies in the P3D world are not the same as those in the published charts, or even do not exist. I use a free application called Little Navmap with which I can search its maps, find the destination airports and see there the real frequencies used in P3D.

So, if you are doing an automatic ILS approach (both COM frequencies in AUTO on FMS) and things don't happen as they should, simply change the frequencies to those indicated on the P3D world.

Grande abraço e fique em casa,

[frmdes]

Oi Felipe,

I am from Rio and happy to meet a neighbor in this forum. I have been testing this KA since the first version 5 years ago and I can say now, it is almost done. I started to fly the last (good) releases early last year, intending a full round the world with the KA starting from Ushuaia (Argentina). Now I am crossing the Quebec Province (Canada), preparing to attack Greenland and Iceland to reach Europe.

As you might conclude, in this trip I've experienced many types of approaches, and some of them with the same problem you had in the SBCT ILS-W 15. During this time, the Milviz crew fixed bugs and tuned the nav systems at a point we should today trust 90% the RNAV behavior. Some we descend perfectly, like an ILS, but others we have to hold the horse ourselves, otherwise crash!

One thing that is very important on ILS approaches, is that sometimes the frequencies in the P3D world are not the same as those in the published charts, or even do not exist. I use a free application called Little Navmap with which I can search its maps, find the destination airports and see there the real frequencies used in P3D.

So, if you are doing an automatic ILS approach (both COM frequencies in AUTO on FMS) and things don't happen as they should, simply change the frequencies to those indicated on the P3D world.

Grande abraço e fique em casa,

Oi Heron!

I'm also from Rio!
Thanks for sharing your experience, i'ts glad to hear that outside Brazil the aircraft is performing the approach phase very well. I allways update my default prepar3d navdata using the aero.sors.fr application, combined with navigraph. It maintain the default prepar3d database, such ILS and VOR's frequencys allways updated. And i always keep my eye to see if the proline is recognizing the ILS indication before proceed the approach.

Abraços!
Felipe Mendes.

[frmdes]

I just updated to 1.1.6 version and am sorry to say, but the approach problems still persist. The only improvement was the glideslope, that so far is doing fine. But the VNAV is not complying the previous intersection constraints very well (IF and FAF intersections), passing at least 1000ft above than it should, forcing me to disable VNAV and descend via VS untill reaches the FAF altitude before glideslope.

[Taguilo]

Hi Felipe,

I flew the same approach of your example without any issues,VNAV was always complied.
I took some pictures of the fligtht that perhaps might help to understand VNAV behavior.

SBCT1.jpg (365.57 KiB) Viewed 2593 times

1) VNAV active, TOD displayed. You can see SOVTA restriction to cross AT OR ABOVE 7000 ft. The FMS has built a path that will cross SOVTA above that altitude. Preselector positioned to a lower altitude, PATH is armed.

SBCT2.jpg (317.37 KiB) Viewed 2593 times

2) Path is captured. AP in VPATH mode, ALTV armed. Vertical PFD VNAV pointer is centered, same as lateral. LOC diamond still way off.

SBCT3.jpg (383.17 KiB) Viewed 2593 times

3) Turn anticipation crossing SOVTA. As you can see, crossing altitude is well above 7000 ft, but complies with VNAV path. However, due to tight turn, VNAV path can no longer remain captured so mode reverts to VPTCH - You can notice white MSG legend on PFD and NO VPATH message on CDU telling there is too much crosstrack error on that turn. Once VPTCH is active, after 20 seconds PATH will arm again and VNAV will be able to recapture it. Notice also APPR FMS mode is already selected and active; APPR LOC and GS are both armed and VNAV is commanding the descent.

SBCT4.jpg (355.65 KiB) Viewed 2593 times

4) As stated before, VPATH recaptured; LOC still armed, lateral blue diamond still far away.

SBCT5.jpg (344.11 KiB) Viewed 2593 times

5) Localizer capture, AP mode changes to APPR LOC; VNAV is still commanding the descent in VPATH mode. Notice that VNAV restriction for TEDUG is AT OR ABOVE 5500 ft, so the path might well be to cross TEDUG above 5500. However, due to the mode a VNAV descent is performed on NAV to NAV procedures, VNAV is commanding a level off 1 to 5 nmiles before the GS capture point, so to allow the aicraft perform the capture being in level flight. In this case, VNAV takes TEDUG restriction and levels off at 5500 ft.

SBCT6.jpg (348.44 KiB) Viewed 2593 times

6) Previous to GS capture. Notice VNAV is still commanding the descent, and has leveled off at 5500 ft. GS blue diamond is coming to center.

SBCT7.jpg (363.88 KiB) Viewed 2593 times

7) Full ILS capture before PULAR (FAF.) Aircraft has left VNAV and is following the glideslope. Preselector has been raised to Missed Approach level.

SBCT8.jpg (340.18 KiB) Viewed 2593 times

8) Aircraft has crossed the FAF and is on GS path to the runway.


As you can see, the entire approach was flown without manually selecting any VNAV vertical mode.
Hope this helps.


Tomas

[frmdes]

Thank you for your explanation Tomas!
There's something you did that i never tryied before. You hit the APPR button before IAF position. I usually do that when i'm already in the final course, at the lower altitude before glideslope. I didn't know that is the correct way to use the APPR button. Will try this, and feedback you later!

Regards,
Felipe.

[frmdes]

Just updating to say that was really my fault, the VNAV is working very well on ILS NAV to NAV approach phases (didn't tested RNAV yet). I just had to execute the APPR mode before IAF, that i never did before.

Every update is making the plane better, congratulations for your hard work!

Regards,
Felipe Mendes.

[paulohenriqued19]

boa noite, também estou tendo problemas com o meu KA, utilizado serviço navigraph para manter tudo atualizado e visualizar as cartas. No painel sempre acionado o VNAV nas SIDs e STARS ele respeita as ATLS, porém quando identifica o ILS ou RNAV não faz a descida do Glid Slope correta, chegando alto ou baixo.
Alguém para me ajudar ?

[Heronjr]

boa noite, também estou tendo problemas com o meu KA, utilizado serviço navigraph para manter tudo atualizado e visualizar as cartas. No painel sempre acionado o VNAV nas SIDs e STARS ele respeita as ATLS, porém quando identifica o ILS ou RNAV não faz a descida do Glid Slope correta, chegando alto ou baixo.
Alguém para me ajudar ?

Hi Paulo, vou tentar ajudá-lo. But we will be talking in English because this forum has rules. You must use autotune to make ILS approaches. It is easier than the traditional methods.

1. Go to the FMC Tune page and enter the ILS frequency on both sides, left and right.
2. Click on the left side frequency button and a new page will open. Click on the auto/manual button to highlight the AUTO option.
3. Make the same at the right side frequency. Both frequencies now are in AUTO.

When approaching, a few miles before the destination, you will see that a dashed arrow will appear n the PFD/MFD maps. Make the normal approach to intercept the ILS, and press the APPR button to catch the GS. Of course, it is better to capture it from below.

If you want detailed instructions in Portuguese, PM me, and we can talk.

Abraço