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ILS Approach - End up below glidepath and stalling with extreme pitch up


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Hi all,

 

I've put off posting here as I'm sure this is problem between chair and joystick, however I'm having a really hard time with ILS approaches.

 

Everything else is going great, from cockpit and aircraft prep to cruise and descent perfectly following the snowflake. However, when I select approach mode and change the nav mode to LOC1, the aircraft acts as expected and turns to capture the localizer and pitches down to capture the glideslope.

 

The problem comes at about 10 - 15nm, with the aircraft falling below the glideslope regardless of speed. It will then pitch up aggressively to try and chase the green (blue?) dot.

 

I'm generally hovering about 200 knots and this point, getting ready to deploy further flaps after going to flaps 1 around 220.

 

I've also reviewed the below:

 

We have four reasons for not flying right:

1. Using LEGACY versus MODERN flight model => chnage to MODERN - Confirmed using MODERN

2. Weather with icing condition which in MSFS is only putting way too much weight onto the aircraft =>switch to ICING only VISUAL effect - Have set it to use visual only

3. Incorrect loading from EFB to Sim - sometimes a double click helps - Had to double clock, but confirmed it set correctly

4. The CoG slider is fulle to the left => put it fully to the RIGHT (35%) - Confirmed

 

Any pointers would be greatly appreciated, and happy to answer any questions!

 

Thanks

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Same Problem here. Approach ING ils 04 at lsgg. Localizer fine captured. 6000ft, nav source loc1, approach Button active, when entering glide slope, aircraft pitch rapidly down, ins a nearly uncontrollable flightangle, below the green GS point on pfd. Then Manual Autopilot disconect an Manual landing work fine. Any Suggestion? 

 

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Maybe this helps:

 

Try to reduce your speed to be at 170-180 kts on intercepting the GS, then reduce in steps of 10 kts on the Glide selecting more flaps and gear after reaching the desired next step.

Be very sharp on loosing the GS, react immediately and make small corrections, keep an eye on the VS that should be somewhere between minus 600 - 800 ft/min (5x your groundspeed=VS to be on 3 degrees glidepath).

Do not pay attention to much on the FD, i yet have to find any good FD in FSX, P3D or MSFS (specially during ILS fase).

 

Be aware on selecting the last flap setting......the pitch attitude and specially the speed of the aircraft is changing very rapidly...when you are able to control that...it will settle down on more stable descent....so do not select the final flapsetting to low.

 

Regards,

Ben

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I had a couple of approaches yesterday where the approaches were all fine, also the GS worked perfectly. Today i had the same issue: As soon as the GS is intercepted and becomes green in the display, the airplane goes into a dive.

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I'll add my experience here, this was approaching KCLT on the 36R ILS. I approached from under the glide slope. Localizer was already captured. Approach mode armed. Speed ~170 IAS with flaps deployed (though I do not recall if it was flaps 20 or 45). 

 

When the glide slope captures, the green dot for the descent profile appears to be correct, no issue there. But the flight directors target a very aggressive nose down attitude, which the autopilot then follows. At this point you get further and further below the green dot for profile.

 

So again the green dot for descent profile seems fine. The autopilot seems to follow the flight directors correctly. But there is a disconnect between the flight director and the profile / green dot.

 

Edit: I will add that I canceled the A/P when this happened so I can't speak to whether it would have then gotten to the point of going extreme nose up. But at least at the point where the G/S is initially captured, for whatever reason the FD's command an aggressive nose-down trajectory.

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Just want to add something that worked for me if you encounter the nose-dive (which happened only twice in almost ~15 hours with the module so far), turn off the AP and cycle the FD on/off, then engage AP -> APPR again.

 

Provided your descent profile isn't bent out of shape too much it reengages the FD back on proper numbers to continue the approach. Best of luck!

 

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Follow-up to my previous post, did another flight terminating at the same destination, same runway, same approach. Intercepting G/S from below at same altitude, similar speed, similar (probably?) flaps. This time it captured and worked flawlessly.

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Hi all,

I got the same behaviour : LOC captured, below GS, APPR mode activated, AP source to NAV1. As soon as the glide scope is intercepted, the plane dives, and I have to switch AP off to do a manual landing.

 

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47 minutes ago, michael-t said:

I have this problem only when I am too fast on approach. As long as I am fully configured for landing and not more than 10kts above Vref, it keeps precisely on the glidepath.

 

Michael

That is often too slow on approach...

 

Got the same problem on the 08L at EDDM

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16 minutes ago, Isaac Romero said:

Maybe will be fixed soon

.

I'll be perfectly honest, if this was the kind of attitude most devs had with issues that were plaguing their product, folks would be more than happy to tolerate the issues until it's fixed. I applaud Hans for taking this step to correct the issue.

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15 hours ago, Swiss Virtual Pilot said:

Same Problem here. Approach ING ils 04 at lsgg. Localizer fine captured. 6000ft, nav source loc1, approach Button active, when entering glide slope, aircraft pitch rapidly down, ins a nearly uncontrollable flightangle, below the green GS point on pfd. Then Manual Autopilot disconect an Manual landing work fine. Any Suggestion? 

 

 

What is with these "me toos" when people are talking about the nose diving when the post is about "extreme pitch up"? It just clutters the thread.

16 hours ago, Jersey1985 said:

However, when I select approach mode and change the nav mode to LOC1

Odd, I swear mine auto changes. I know it has done so at least twice. That would tell me that there is an issue with nav source switching.

The most obvious one, are you radios set to Auto-tune? The Dudes video shows him setting them to Manual. Now obviously if the plane is flying on GPS (enroute navigation) then tries to switch to the radios on ILS capture with the radios set to the departure frequency that will be a bad thing.

 

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  • Developer

Yes indeed the nose dive and flying with high pitch and loosing control are two different but maybe associated problems.

1. The nose dive is an issue we have recognized and working on it. This is loosing the GS by slowly and then faster descending below the GS

2. The high pitch on a GS and running out of trim to to maintain GS is a different reason to be found.

 

 For the latter I suggest as guidance: The right speed on the GS with the different speeds and flaps settings is when the pitch is 0-1 degree, so pretty flat. 
 

The correct speeds to fly an approach are for a 28.000 kg = 62000 lb aircraft

Intercept LOC 200 and Flaps 2

Intercepts GS 180 and Flaps 3

Established GS  160 Flaps 4

On final 130 GD Flaps 5

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  • Developer

Because we believe this topic has been answered we have closed it. If you have any more questions feel free to open a new topic.

 

if you have further questions or comments please split them out into the relevant subject et or ad it to already open threads.

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