FD horizontal guiding when landing

[BlueStar 323]

Gerald,

How does it fly with the HUD?

Just a piece of real world advice, don't do what the FD is telling you, do what the airplane is telling you.  

blaustern

 

[GEKtheReaper 364]

@Bluestar With HUD I always hold that "small circle" in the TD zone of the RWY and land all the time (well not perfect but) pretty good (but again, I have to have a visual on the RWY for that).

[skelsey 765]

1 hour ago, GEKtheReaper said:

The FD should point you (HDG and pitch) in the right direction that would be necesary to follow a certain path.

No -- it provides steering commands to achieve a particular trajectory. Thus your statement...

1 hour ago, GEKtheReaper said:

Since the FD should be related to ACFT HDG and not to ACFT roll, if the pilot banks the ACFT short left/right without a change in HDG, there is absolutely no reason at all to see the FD acting like a pogo stick from left to right.

...is not quite correct.

The FD does not care about the aircraft's heading as such, it commands a roll (I suppose more accurately a rate of heading change -- I haven't looked what it does in unbalanced flight) in order to achieve the target heading. If only a small roll is required, the FD bar will only deflect a small amount. If you roll further/change heading more quickly than the FD has calculated it would like you to, you will indeed "roll past" the FD and it will deflect in the opposite direction, which is what is happening here.

1 hour ago, GEKtheReaper said:

Observing the ND in the video you will see the pilot flying a HDG of 280...281 (minute 30:23).

The FD is not centred at this point: it is very slightly deflected to the left (look at where the FD bar is in comparison to the pitch index symbol: just going through the left edge, not dead centre). The pilot then rolls further to the left than the FD is commanding and so "rolls through" the FD command, and so the roll bar moves to the right.

1 hour ago, GEKtheReaper said:

In the real cockpit view you will also see the roll adjustements but the FD will not budge from the middle.

Look how much smaller the roll inputs are in the real flight deck though. As it happens, if you look at around 6:30 and 6:45, some sharper, larger left roll inputs are made and you will notice that the FD moves across to the right, albeit in a smoother manner than in the sim video (but then the inputs are smoother and smaller also).

[Spin737 102]

In the video, it's almost as if the guidance cue is simply hanging from the Sky Pointer.

Even with a 90-degree turn, the F/D smoothly slides over to the side in the real thing. It's pretty slow to correct. The autopilot will very strongly follow the cues, but I don't think I've seen the F/D that jumpy and I've been in some bad turbulence.

I'm heading to the sim in a few weeks. If you guys don't have it sorted out by then, I'll see what a "real sim" does if I get a chance.

[BlueStar 323]

1 hour ago, Spin737 said:

In the video, it's almost as if the guidance cue is simply hanging from the Sky Pointer.

Even with a 90-degree turn, the F/D smoothly slides over to the side in the real thing. It's pretty slow to correct. The autopilot will very strongly follow the cues, but I don't think I've seen the F/D that jumpy and I've been in some bad turbulence.

I'm heading to the sim in a few weeks. If you guys don't have it sorted out by then, I'll see what a "real sim" does if I get a chance.

Matt,

I don't put as much trust in the F/D as a lot of folks.  For me I find the F/D tends to lag behind what I am trying to do when hand flying.  For that reason I tend to turn it off especially when hand flying visual approaches.  I know I'm just old and old school, but I'm going to do what the airplane is telling me, not the F/D.  

blaustern

[Spin737 102]

42 minutes ago, Bluestar said:

Matt,

I don't put as much trust in the F/D as a lot of folks.  For me I find the F/D tends to lag behind what I am trying to do when hand flying.  For that reason I tend to turn it off especially when hand flying visual approaches.  I know I'm just old and old school, but I'm going to do what the airplane is telling me, not the F/D.  

blaustern

It's more of a Flight Suggestor for me. I flicked it off coming in to MCO yesterday. Storm on final so we made a short visual to a new runway. F/D wasn't gonna help me much.

[GEKtheReaper 364]

@skelseyThank you Simon (and all others: @Bluestar, @Spin737) for your time and explanations.

Since I'm certain Simon that you are more experienced then I am, I must trust your judgement and drop my idea of a "broken" FD.

Nevertheless, I think that some of the other users (maybe pilots), that again seem to be more experienced then I am, "feel" the same about the "jumpines" and "lagines" of the FD. Maybe PMDG might have a look into this for further updates.

Regards from lake Constance.

Gerald

[downscc 1,327]

8 hours ago, GEKtheReaper said:

Maybe PMDG might have a look into this for further updates.

There are not going to be any updates to this product because of its age.  Expect PMDG to work on a major revison along the lines of the QOTSII, just don't expect it soon.

[kevinh 409]

post deleted

[GEKtheReaper 364]

I've tried again some landings using the HUD. It is much more easier to follow the Little circle with the ACFT Symbol. It feels more accurate. I also found the difference what was bothering me:

As @skelseyexplained, the FD provides "steering comands". Here is the odd Thing: lets say you Approach EDDM 08L/R and you have 90° sidewind from right (170°). If you are positioned right of the GS (Diamond to the left of the center) and fly RWY HDG, the wind will push you slowly to the left (thus towards the RWY CTR). If the FD will calculate that you will touchdown on the RWY CTR, it will not provide you with a steering command (which teoretically is correct).

It is odd because the FSL FD behaves a bit different. Given the same Approach as above, it will first guide you to the RWY CTR (CTR on GS) and then will tell you to turn your nose slightly into the wind so that the ACFT will remain CTR on GS.

I think that the second example is much more accurate. I have never seen ACFT flying RWY HDG with an Offset to the RWY so that they touch down in the Center of it. What if they have a windshear?

The FSL Approach and FD guidance resembles IMHO the real world. You have to be CTR on the GS all the time and compensate the sidewinds turning the nose into them. 

[Jovabra 18]

As always very good information:
 

 

Regards Jo va Bra

[GEKtheReaper 364]

@Jovabrathank you mate for this beautiful video!

Pranas is explaining exactly what I expected the FD behaviour should be. In the landing section he explaines how he points the ACFT nose 16° into the wind to fly "sideways" towards the RWY maintaining its center line. You can see both FD beeing centered all the way until touch down.

The PMDG's FD will not act the same: it will be centered with the ACFT flying RWY HDG with an offset to the right of the GS. IMHO this is wrong since it should assist you in keeping your CRS (not to fly a parallel CRS which will intersect your WP due to wind....).

 

Regards,

Gerald