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Nick Dobda

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So your AOA and speed were jumping all around like that?  I wouldn't even try that approach, even if I had no LLWS reported/warnings.  Plus that was simulating a microburst, which is different. 

The problem in the sim is that you lack RW warning systems and the ability to sense what is happening.  In the real world I believe you can kinda predict where you are in a situation and apply the appropriate escape maneuver.  The LLWS escape is to disconnect AP and AT and firewall the throttles, then aim for 15 degrees of pitch.  In microburst situations they will employ a variable pitch scenario, whereby you pitch down slightly then level off then climb out of it.  i

I just don't know that the sim is going to give you those real world chances to escape.  It's important to remember, no pilot is safe from adverse Wx.  If conditions are bad than anyone can be killed.


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Didn't realize this airport is enhanced by Orbx FTX US freeware pack.  I flew there from CMH in the Duke.  It seemed like the ILS was offset, and I don't see why.  It doesn't mention that on the plate.  Also, RW weather for now, but time set to day light gave me a low ceiling and fog.

2017-5-5_22-57-40-439.jpg


- Chris Jefferies

 

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3 hours ago, Nick Dobda said:

This is what happened... Less any warnings whatsoever. I've been wondering for the longest time when conditions would come together and I'd get a wind shear alert on an approach while having live atc.. Wondering how I would handle it. Would be a shame if a fluke prevented the warnings from going off. If I had a few seconds of warning I would have mashed the throttles and went around instead of riding it to the ground. 

Im not missing a setting or anything, right? You don't have to activate anything to get the warnings on do I? 

I would not entirely rely on the warning system. It's there to help you identifying dangerous situations, but not a substitute for your knowledge and experience. When you suddenly gain 40 knots of airspeed, you know it's possibly some serious windshear. I wouldn't wait to push that TOGA button when hundreds of lives depend on it.


David Chen

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6 hours ago, Orlaam said:

It seemed like the ILS was offset

2017-5-5_22-57-40-439.jpg

Yes, when I turned to final it lined me up way left. I had to disconnect everything at that time and pull it back to line up properly. 

As the the last post discussed, I did a lot wrong, it was likely an unstable approach that should have been aborted anyway. I wasn't getting 30 knot gains, but it was jumping around maybe 10 knots. But I think it was an asn16 microburst that dropped me, just wondering why no warnings.

 


Nick Dobda

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Nick, I watched your video. That not only looks like windshear but also a major downdraft. I don't know what AS16 does or if this happens this way in real life. There are four anemometers on each quadrant in major airports and if there is a discrepancy of either 10 knots or more than 10 degrees in wind speed and direction the tower alerts aircraft. there were thunderstorms around, so I don't know what the NGX felt but your airspeed dropped to 70 KIAS so the 737 definitely stalled.

I believe something similar happened in real life to a Delta DC-10 was it ? at DFW many years ago. Did you make the decision to abort landing and added go around thrust when the wind shear alarm came on ?

 


Alberto Ferracuti

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1 hour ago, ALF1 said:

I believe something similar happened in real life to a Delta DC-10 was it ?

WEL, you got the number of engines right, but it was the L-1011.


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Alberto, that's not my video. I picked this YouTube because the plane acted like this one did except I had no windshear warnings or stall warnings. In my case it just dropped.

it seems like I hit a microburst but had no advanced warning. I'm just now wondering if this scenerio can occur in the sim - that is to get a microburst with no advance warning.

I realize the sim isn't real life and there isn't really a windshear scanner scanning the virtual air, it is all programming. Just wondering if as16 told the ngx that a burst was coming and the ngx didn't receive the message to sound the warning or something.

 


Nick Dobda

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15 minutes ago, Nick Dobda said:

Alberto, that's not my video. I picked this YouTube because the plane acted like this one did except I had no windshear warnings or stall warnings. In my case it just dropped.

it seems like I hit a microburst but had no advanced warning. I'm just now wondering if this scenerio can occur in the sim - that is to get a microburst with no advance warning.

I realize the sim isn't real life and there isn't really a windshear scanner scanning the virtual air, it is all programming. Just wondering if as16 told the ngx that a burst was coming and the ngx didn't receive the message to sound the warning or something.

 

AS doesn't work that way.  It sends weather to the sim and the plane responds in real time.  No advance warning will be there.


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8 hours ago, Orlaam said:

AS doesn't work that way.  It sends weather to the sim and the plane responds in real time.  No advance warning will be there.

Ok, there is a windshear warning though, does as16 give the "windshear!" Audible warning? I know the Wx display should also display something too. In the video I found there is an audible warning, but I see there was nothing in the Wx display


Nick Dobda

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There are two windshear warning systems in the aircraft, not one. The first windshear warning that was developed is usually part of the EGPWS. This detects differences between inertial accelerations and pitot-static accelerations. A windshear will initially affect the pitot-static system, inertial velocities will take time to be affected. If the differences are large enough you get a windshear caution if the accelerations are forwards or updards and a windshear warning if they are downwards and backwards. It also senses OAT. If that starts dropping suddenly it's a sign of possible windshear in the vicinity and produces a windshear alert (steady amber, not flashing).

More recently, predictive windshear was developed which uses weather radar returns to detect high rain drop velocity, indicating a strong windshear. That shows a windshear graphic on the Wx and also gives an aural warning. The EGPWS windshear is now referred to as reactive windshear warning.

Whether PMDG simulate either I don't know. Data for predictive windshear should come from AS16/ASN. I've certainly seen windshear shown on the ASN map. Reactive windshear warning would be entirely a matter of PMDG modelling of reactive windshear. It's a shame that video doesn't show the weather radar otherwise it should also show whether the windshear warning is predictive or reactive.


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25 minutes ago, kevinh said:

It's a shame that video doesn't show the weather radar otherwise it should also show whether the windshear warning is predictive or reactive.

IIRC the audio for a predictive windshear alert is 'WINDSHEAR AHEAD', compared to the reactive warning 'WINDSHEAR, WINDSHEAR' as heard in the video.

AS itself can provide windshear data: I presume predictive as well as reactive. There is an option in ASN to enable or disable the windshear audio alert: I don't know whether PMDG have included windshear/PWS in their radar simulations but as it simply receives data from AS in theory it should be possible to simulate (unless AS simply doesn't pass windshear data in the radar data feed, but that would seem strange).


Simon Kelsey

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26 minutes ago, skelsey said:

IIRC the audio for a predictive windshear alert is 'WINDSHEAR AHEAD', compared to the reactive warning 'WINDSHEAR, WINDSHEAR' as heard in the video.

AS itself can provide windshear data: I presume predictive as well as reactive. There is an option in ASN to enable or disable the windshear audio alert: I don't know whether PMDG have included windshear/PWS in their radar simulations but as it simply receives data from AS in theory it should be possible to simulate (unless AS simply doesn't pass windshear data in the radar data feed, but that would seem strange).

Yes, you're right that the predictive warning aural is "windshear ahead", I'd forgotten that. So that means PMDG have modelled reactive windshear. I don't think AS is/should be the source of reactive windshear data, it's too reliant on aircraft type (a small aircraft will react differently to a large one in the same shear). AS knows about the wind vectors it is modelling, that doesn't easily translate into aircraft accelerations. Reactive windshear warning must surely be simulated in the aircraft addon, as a result of the aircraft response, not the weather engine.

There may be other reasons why an alert isn't triggered. Maybe the warning trigger level is set quite high to prevent too many false warnings and so only very strong windshears get reactive warnings? Low framerate might prevent transient changes being detected. Variable framerates could screw up calculation of accelerations.


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Asn has an audio checkbox you say... I'll start there when I have time to fly again. Maybe that's why I got no warning

 


Nick Dobda

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