But how do you determin what is below you, on path and what is above you? I can see the tilt settings in those Pictures is -2 AVG

 

Michael

But how do you determin what is below you, on path and what is above you? I can see the tilt settings in those Pictures is -2 AVG

 

Michael

That is on automatic mode. At that altitude, most of the weather is -2 apparently. The tilt will change as you climb or descend, or when weather is much higher or lower than usual.

 

You can manually tilt using the tilt/gain knob. Just watch Kyle's video.

That is on automatic mode. At that altitude, most of the weather is -2 apparently. The tilt will change as you climb or descend, or when weather is much higher or lower than usual.

 

You can manually tilt using the tilt/gain knob. Just watch Kyle's video.

 

 

Thanks , will look into Kyles video but,

 

But he shows first a picture with a Red Cell with -2 AVG in Auto and also a green Picture where he tells us its below him also with -2AVG in Auto 

 

How does he determin that the RED cell is in path and the green cell is below the path ?. AVG is minus 2 in both picture 

 

Michael

 

Thanks

Michael

Thanks , will look into Kyles video but,

 

But he shows first a picture with a Red Cell with -2 AVG in Auto and also a green Picture where he tells us its below him also with -2AVG in Auto 

 

How does he determin that the RED cell is in path and the green cell is below the path ?. AVG is minus 2 in both picture 

 

Michael

 

Thanks

Michael

 

The red cell is actually -2 degrees (down) from the radome. It's not exactly in front of him. This is to monitor weather below you to avoid heavy turbulence at the very least.

 

 

I believe what he meant to say was there is weather ahead, but not at straight ahead at his altitude. As he climbed, the nose-up pitch picked up the top of the storm and that's the green and amber return you see at the end. That's what I believe

 

Beta testers correct me if I'm wrong.

Bob, This WXR implementation is quite different from RXP or any other radar implementation in that it gives you a literal picture of the actual weather and where it is/isn't located. Unless I'm mistaken, all other WXR's to date provide an approximation at best of what weather is out there (i.e if it's raining/turbulent where you are, the radar shows a picture like what you'd expect to see, but not an exact decpiction). Some of them are purely eye-candy.

Darn. Had a feeling that some would take my comment out of context. I meant that weather radar that has SOME functionality, as demonstrated by RXP with their product, is NOT NEW TECHNOLOGY. I was not referring to what PMDG has accomplished. And since the ability to put SOMETHING like RXP's rendition into a sim product has been around for some time, it has always amazed me that other providers have not included same, as a minimum.

 

Anyway, it will be nice to see what PMDG has done and have this improved capability for future add-ons as well.

The Auto mode is trying to give the pilot the best picture of the weather to maintain SA, based on its own logic (of which, I'm not exactly sure other than the following observations):

• CLIMB: Maintains an on-the-nose stance, until higher up, where it begins to "look ahead"
  Basically, it's looking up into the sky where you're going to be in the initial climb, and as you reach the flight levels, begins to look ahead (your climb angle has been reduced at this point, just based on performance, and you're transitioning to the "above the weather" areas)
• CRUISE: Maintains a cruise pitch offset
  Basically, it's assuming you're pitched up around 2 degrees, so it lowers the radar two degrees to look directly ahead.  Sure, you may be at 3 or 4 degrees, but 1 to 2 degrees isn't going to destroy your awareness of the weather around you.  Again - in AUTO - you're looking at weather at your altitude.  Need to look below?  Manual mode.
• DESCENT: Leads your descent
  Basically, because your nose angle generally isn't at all your path angle in the descent (you could hold your nose at 0 and reduce thrust to descend at a negative path angle).  Because your nose is pointed just about straight ahead, and not at the weather below you, the radar is tilted down to look down at the weather below.

What you're seeing in the pictures is:

1. Weather depiction - long range
2. Weather depiction - short range (this change simply through adjusting the range of the ND
3. Weather depiction - effect of pitch on radar image

To clarify point 3:

In image 1 and 2, the aircraft nose angle was +3.  Radar angle was -2.  Resultant radar evaluation at a +1 degree angle (looking ever so slightly up - that weather in the first two shots was at the same altitude, and slightly higher).  In image 3, the aircraft nose angle was +5.  Radar angle was -2.  Resultant radar evaluation was at a +3 degree angle.  The weather depicted is above the current altitude, which is why the depiction looks a lot less cluttered - only some of the weather is that high up.

D'oh! Forgot that the airplane is pitched a few degrees at cuise  :Doh:

D'oh! Forgot that the airplane is pitched a few degrees at cuise  :Doh:

 

haha - thus the -2 from the AUTO tilt.

 

Weather below you doesn't quite matter.  Granted, it can still affect you, as would be the case with lower-level weather that was convective (and therefore "climbing up towards you"), but in most cases, you only really need to pay attention to what you would be flying through:

• Weather at altitude;
• Turbulence at altitude

Not something most people think about, though, which is also why many people didn't quite figure out why I was so vehemently opposed to most sim depictions of weather "radar."  It's all about the slices of the weather that affect me.  I couldn't care less about what's down at 8000 when I'm up at FL320.  That shouldn't be showing up on my radar.

All the RADAR's I have worked with are stabilized in the AUTO position. Which means that if a set my beam to 0° I will get the same returns if I maintain the same altitude. The 2° nose down at higher altitudes compensates for the beam height of around 2° as well as to give a better idea of what type of weather it is.

A cumulonimbus will show as bright red at mid levels but may become only a speck of green up higher. However knowing if that speck of green is a CB top or just dense cirrus may help you judge on weather to divert or not.

As such, with the RADAR in AUTO, the weather depiction should not be affected by the initial nose up motion, but with rising altitude.

 

Bear in mind that on the 777 this may be completely different than in my experience of working with WX RADAR's.

 

Cheers,

For now, yes. No other developer is able to produce the data neede to get an accurate weather radar working. This may change in the future, of course.

 

Thanks for Information!

 

Wow Kyle. Glad i asked :-) Thanks alot

 

Michael

 

 

Wow Kyle. Glad i asked :-) Thanks alot

 

It was a good question.  You're welcome!

[*]CRUISE:

Basically, it's assuming you're pitched up around 2 degrees, so it lowers the radar two degrees to look directly ahead. Sure, you may be at 3 or 4 degrees, but 1 to 2 degrees isn't going to destroy your awareness of the weather around you. Again - in AUTO - you're looking at weather at your altitude. Need to look below? Manual mode

I dont know which weather radar panel PMDG has selected, but ours does not work like that at all.

There are different weather radar panels available and I have not looked at how others work, but the theory behind it....as to where you should look, is the same.

 

We have the one that you can see on page 11.10.16 of PMDG777 FCOMv2.

 

As the description sais, the tilt knob will give you an angle below HORIZON!

Not below your nose!

So tilt -2 means you are scanning 2 degrees below the horizon.

And since the weather radar is coupled to INS, it knows exactly where the horizon is.

Even if you increase pitch for a climb, and tilt is set at -2, you will still get a radar return of 2 degrees below the horizon!

The tilt mechanism, coupled to the INS corrects automatically.

(ofcourse I do not know if this is modelled like this by PMDG!)

 

Why does it look 2 degrees below the horizon in auto mode?

Because looking straight ahead is quite uninteresting in real life!

 

What you see on that weather radar are water dropplets (as you know).

What you do NOT see is water vapour, ice christals and hail.

A CB (rain cloud or thunderstorm) can/will have all of them up to several thousands of feet above your red/yellow, even green radar return.

So straight ahead you might SEE NO return....but there can be the top of that thunderstorm full of ice christals, maybe hail but definately turbulence!

So seeing no echo does not mean you are safe there.

I can promise you......you do not want to fly right over the top of a viscious thunderstorm even if you have no echo straight ehead. You are in for some serious turbulence, and possibly worse (hail, static discharges, lightning strikes and engine damage).

 

We look down....way down, so we look into the hart of that aggressive part of the thunderstorm.

That red an yellow area at 20.000 to 30.000 ft. And then we judge how bad that thing is.

And the higher you fly, the further you have to tilt down (I use -3 at FL370 and higher) to see into that hart.

At minus 3degrees and FL370 you are looking at around 25.000ft when that echo passes the 40nm range arc on your ND, and so you make sure you are not missing anything.(as in looking straight ahead).

Once you have that that thing on screen you can start sliceing upwards to see where the red/yellow stops and then further up to see where the green stops.

 

Depending on the size of the rain cloud you fly over it if WELL above......or around it.

 

Using weather radar correctly is not as easy as one might think.

 

 

As the description sais, the tilt knob will give you an angle below HORIZON!
Not below your nose!
So tilt -2 means you are scanning 2 degrees below the horizon.
And since the weather radar is coupled to INS, it knows exactly where the horizon is.
Even if you increase pitch for a climb, and tilt is set at -2, you will still get a radar return of 2 degrees below the horizon!
The tilt mechanism, coupled to the INS corrects automatically.
(ofcourse I do not know if this is modelled like this by PMDG!)

 

That could very well be the case.  I'm just approaching it from a very abstract case.  Based on how the system always says -2A, my bet is that it's doing what you're saying.  That and the note by the other MD80 driver, I'd be willing to concede that your description is much more accurate.  I bet that's how they've simulated it, too.

Yes it looks like PMDG simulated it corrcetly.

 

Mark's 2nd picture shows +2.5 attitude and -2 degrees tilt in FL390

You would never see a red return in FL390 if -2 tilt meant you are looking at +0.5 degrees up from the horizon.

 

Looks good :-)