Aaron, there are so many unknown variables in your videos that it is virtually impossible for anyone to say with any certainty what might be causing your alleged landing problem.   For example, you do not say what your landing weight or approach and touchdown speeds are, at what point you are selecting and applying reverse thrust, what autobrake setting (if any) you are using, if you are inadvertently applying manual braking instead, if you have armed the auto speedbrakes, what the landing conditions are (OAT, W/V etc), or if what you are seeing is more pronounced with Flaps30 compared to Flaps25. 

What I can say is that your videos do not appear to resemble anything like a genuine hard or bounced landing, so I think you can rule that one out.  I also don’t think the different landing gears touching down is anything to go by either, but as others have already said perhaps your terrain/mesh scenery could be a factor, although I don’t know. Whatever the reason, it is easy to forget when flying aircraft like the PMDG QOTS that this is a PC simulation and not the real thing!

If you look closely at your first video (v4 02 11 2018 19 11 29) I think you will see what I mean by your unknown variables, because I can see evidence of a poor flare and landing technique here.  First of all you were slightly high on the approach during the last view of the PAPIS, then at 50 secs into the video it looks as if the nose is raised by more than the normal 2 degrees in the flare. The aircraft then floats for a few seconds before at approx 54 seconds a rapid nose down pitch change can be seen, but there is no immediate increase in elevator deflection to compensate for this until some two seconds later (ie. immediately before nose gear touchdown which is far too late). Then, again at 56 seconds and with the nosewheels already on the ground the spoilers can be seen extending fully, which indicates that you were also late selecting Reverse Thrust (the ground spoilers will deploy fully as soon as the main gear touches down when Nos. 1 and 3 thrust levers are closed and provided they have been armed for the landing).

Next time see if this cures your problem: Raise the nose by 2 degrees at 30ft RA for the flare, hold that attitude and at the same time smoothly reduce the thrust to idle. On touchdown immediately deploy the speedbrakes if they haven’t extended automatically and simultaneously apply braking and reverse thrust. You should then smoothly fly the nosewheel down to the runway without delay and DO NOT let it drop.  Happy Landings!

As far as I understood Alex from the tech team already aknowledged that there is an issue....  ?? 

On 11/29/2018 at 1:19 AM, killthespam said:

Aaron,

I did a few landings and I agree with you 100%, there is something going on and I filled the discrepancy on "to do list".

When is gonna get fixed, I don't have an answer. All that I can say is that is on the list.

And also I have to apologize, I had this discrepancy on my list for about 2 month but I forgot to list it. 

Yes there is an issue.

I experienced the aggressive nose down behavior on landing for the first time this morning on the 747-8 in P3Dv4.  In my particular case, I was flying from a known corrupted scenario file which I previously saved.  For whatever reason, when I load this particular saved scenario (747 aircraft on ramp, apu running, and instruments pre-configured for engine start), I have no wheel brakes when commencing taxi.  Nothing I can do will get the brakes to work (engines running, hydraulic system full tilt and happy in the synoptic display), even though I can visually see the virtual cockpit toe brakes moving in unison with my hardware inputs.  Not even the keyboard-assigned brake key has any effect.  Loading any other PMDG 747 saved scenario brings the wheel brakes back online with no problems.  To be clear, the brakes are not overheated as this scenario starts on the ramp, and the tire/brakes synoptic is happy with nominal readings across the board.  

Therefore, I think it's pretty obvious in my situation that I'm dealing with a corrupted scenario file.  Since I've so far only experienced the hard nose down problem when running the sim from this known corrupted scenario file, I'm wondering if this has any bearing on the problem. 

-Rudy Getz

 

Edited December 15, 20187 yr by Reuben Getz

Definitely not in my case.  I made a new panel state from engines running with the latest update, and all has been well since then.  

Quote

Definitely not in my case.  I made a new panel state from engines running with the latest update, and all has been well since then.

 

I now concur, having tested more with different scenario loading.  I've now experienced the nose down moment on landing consecutively with the same CG/fuel/pax loading.  In this particular landing scenario, I have every seat on the Pax version of the 747-8 occupied (every airline's dream!), with about a 5% fuel load and random cargo that works out to 151kts Vref.  Two separate but identical flights with this loadout resulted in a strong nose down moment on landing at the same airport with 'Fair Weather' selected in P3Dv4.  I also shot several approaches at the same airport and weather condition with a different loadout and did not experience any nose down moment on landing.  

Wondering now if a certain CG condition is triggering this behavior?  I can rule out a scenery mesh anomaly at least from my testing.  

-Rudy Getz  

Edited December 17, 20187 yr by Reuben Getz

4 hours ago, Reuben Getz said:

5% fuel load

This tells me nothing.

5 hours ago, Reuben Getz said:

Wondering now if a certain CG condition is triggering this behavior?  

that is what I first thought of because it started happening after they changed something to the payload/CG handling...

 

5 hours ago, Reuben Getz said:

I can rule out a scenery mesh anomaly at least from my testing. 

 

that is the conclusion everybody who sees this issue came to..

 

40 minutes ago, Captain Kevin said:

This tells me nothing.

 5% of max fuel load ?  That is what it is telling me.....but also not really important I guess

 

 

 

But anyway, they are aware of it and will look into it....

 

best regards

Edited December 17, 20187 yr by Sekkha

7 hours ago, Sekkha said:

5% of max fuel load ?  That is what it is telling me.....but also not really important I guess

Yes, I'm aware of that, but not knowing if the particular aircraft in question is equipped with a stabilizer tank or not, as this is an option that can be changed in the FMC, could change the maximum fuel capacity by quite a bit. Fuel weight tells me something. Fuel percentage, not really so much. Now it's extra work for me to go in and figure out what the maximum fuel capacity of the aircraft even is, assuming I ever figure out if it has the stabilizer tank or not, and then I have to sit here and do math to figure out what 5% of that is.

34 minutes ago, Captain Kevin said:

Now it's extra work for me to go in and figure out what the maximum fuel capacity of the aircraft even is, assuming I ever figure out if it has the stabilizer tank or not, and then I have to sit here and do math to figure out what 5% of that is.

sorry for any possible missunderstanding here, just  to clarifiy that:

What I wanted to say is that  I suppose that the exact amount of fuel is not really important data in his post....he basically is pointing out that it is for sure not mesh/scenery  related and rather CG related........So no need to do any maths at all in order to understand his post 

 

 

4 hours ago, Captain Kevin said:

Now it's extra work for me to go in and figure out what the maximum fuel capacity of the aircraft even is, assuming I ever figure out if it has the stabilizer tank or not, and then I have to sit here and do math to figure out what 5% of that is.

It's good to keep the grey matter going doing mental calcs and there's a very easy way to tell if you have a stabilizer tank or not - just have a look on the overhead panel at the fuel system controls or bring up the fuel synoptic on the lower EICAS screen instead.  As for working out 5% of the fuel load, the total weight will vary depending on its specific gravity, but whatever the figure is just divide your total fuel load (in Lbs or Kgs) by 10 and multiply the figure you get by 2 and you will have your answer.  BTW the Stab tank holds approx 10.0Kgs, so you could simply add 2,000Kgs to your old 5% figures if you like! 🙂 

5 hours ago, Sekkha said:

What I wanted to say is that  I suppose that the exact amount of fuel is not really important data in his post....he basically is pointing out that it is for sure not mesh/scenery  related and rather CG related........So no need to do any maths at all in order to understand his post 

On the contrary, I would think that if you were going to try to replicate the situation to see if you could duplicate the issue, knowing how much fuel is absolutely critical. Of course, knowing the cargo weight and the CG in question would help, too

1 hour ago, berts said:

It's good to keep the grey matter going doing mental calcs and there's a very easy way to tell if you have a stabilizer tank or not - just have a look on the overhead panel at the fuel system controls or bring up the fuel synoptic on the lower EICAS screen instead.

I know my plane has a stabilizer tank, it's my plane. I don't know if his plane does, and I'm certainly not in a position where I can see either the overhead panel or the EICAS screen on his plane, so that wouldn't really help.

1 hour ago, berts said:

As for working out 5% of the fuel load, the total weight will vary depending on its specific gravity

Yes, that would be another issue, too, and that would add even more to the math that I would have to do. This is why knowing the fuel weight would help. If you have all the time in the world to try to do math, go for it. I'm not likely to even try, just not enough hours in my day to do it. I'm probably more likely to go see if somebody else needs help with something else at that point.