skysurfer

EGCC departures

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Good day all.

I'm trying to figure out what I am missing here. This is not the first time I have seen this.  

EGCC airport, loaded SID DESIG 1S RWY05L. Based on route out I am suppose to climb straight ahead:

33454961410_a997efa886.jpg

33454957940_2a1e03c922_b.jpg

However this is not what I see on ND:

33454960320_af66fe28ef.jpg

So I was unable to arm LNAV and had to use HDG SEL which is not a big deal but this does not look right. 

Thanks for looking. 

 

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Big help if you had mentioned type aircraft.

The departure is coded such that 05L departure first waypoint is D053A (MCTr053 1DME) with an altitude constraint of at or above 760 then second at D053L (MCTr053 12DME) at or above 4000.  My guess is the aircraft performs the procedure as encoded, the only error is the ND display?  My guess is that this is the PMDG 777?

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So Edward, does the NGX fly the departure as intended?

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Well. I was unable to engage LNAV probably because of that route shown on ND. I used HDG SEL and just climbed straight. What I also noticed that the first heading in LEGS page was 240 or so which was opposite direction, and after that heading  053. 

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I'm not aware of a ND rendering issue like this in the NGX so I had a look for myself.  You should have looked closely, the first waypoint D053A is before the end of the runway therefore the rendering is correct because the flight begins at the end of runway then has to reverse course to the misplaced waypoint. Next time you'll look close.

A temporary fix is easy.  Look at EGGC.txt in the sidstart folder and find FIX D053A LATLON N 53 21.741334 on line 33.  Edit the line changing the minutes to FIX D053A LATLON N 53 22.56 W 2 13.74. Save the file and enjoy your flight.  I picked a point 1.3 nm from end of runway on runway centerline because minimum climb gradient is 5.7% per chart and you should be 50 AGL crossing end of runway.

A permanent fix is to post a bug report at Navigraph forum.  They appreciate such reports.  I suspect that the waypoint is selected beyond the displaced threshold, which in this case is not going to work.

 

 

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Appreciate the research on this issue. I will talk to Navigraph folks. I thought it was NG issue but looks like it just uses data loaded by Navigraph. 

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On 4/5/2017 at 3:07 PM, downscc said:

I'm not aware of a ND rendering issue like this in the NGX so I had a look for myself.  You should have looked closely, the first waypoint D053A is before the end of the runway therefore the rendering is correct because the flight begins at the end of runway then has to reverse course to the misplaced waypoint. Next time you'll look close.

A temporary fix is easy.  Look at EGGC.txt in the sidstart folder and find FIX D053A LATLON N 53 21.741334 on line 33.  Edit the line changing the minutes to FIX D053A LATLON N 53 22.56 W 2 13.74. Save the file and enjoy your flight.  I picked a point 1.3 nm from end of runway on runway centerline because minimum climb gradient is 5.7% per chart and you should be 50 AGL crossing end of runway.

A permanent fix is to post a bug report at Navigraph forum.  They appreciate such reports.  I suspect that the waypoint is selected beyond the displaced threshold, which in this case is not going to work.

 

 

Hello back. 

His the reply from Navigraph:

"I have looked now deeper into your report and sorry to say, but this is an PMDG issue. I will try to explain why:
When you move you A/C to the "displaced threshold line" of RW23R, you see that the D053A is above your A/C and not beyond as you suspected. The displaced threshold is 600ft for RW23R and 1401ft of 05L. The D053A is D0.4 from MCT on R032, this is after after the displaced threshold. Additional, the procedure told the A/C to OVERFLY the D053A, that means that you must pass the waypoint. Third, I´m not sure, from where PMDG should known the displaced threshold because I haven´t found any information in the dataset, so from where should PMDG known this value?

I guess, you´re assumption with the selected waypoint in the displaced threshold is correct (and this is correct in the real-world navigation too), but not in the displaced threshold rather between the two runway coordinates (due the missing information of the displaced threshold) - and that´s not correct and therefore an PMDG issue.

The workaround works yes, but it´s not correct to "tranfer" the waypoint on any place that the procedure looks good? ... the D053A is a defined Place/Bearing/Distance waypoint - MCT/032/0.4 - that´s the exactly definition.

Sorry Edward, in this case I can´t see any navdata issue on our side"

--------------

I am a bit confused what is the relation to displaced threshold of RW23R and SID for 05L? 

I did this screenshot when the A/C was actually at the gate. I spotted this ND line while I was loading FMC for departure with the intent to takeoff on RWY 05L, not 23R.  
When I lined up for takeoff on RWY05L no changes to the magenta line happened. So the A/C was at the threshold of RWY05L not 23R. I asked Navigraph same question, will see what they say. 

 

Thx again. 

 

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It's semantics.  When you are sitting on 05L at the beginning of the pavement, the 05L displaced threshold is ahead of you.  Landing 05L has to be after that threshold.  Beyond the 05L threshold is the opposite direction, 23R, threshold and it has no bearing on your takeoff from 05L.  It only has significance for landing 23R.

If you slew from the 05L takeoff position to the 23R end of the runway, you will notice you passed waypoint D053A before reaching the end of pavement (at least this is what I recall seeing); however, any and all departure waypoints must be beyond the physical end of the runway, regardless of displaced thresholds.

I also don't understand why Navigraph is using MCT DME in placing the waypoint.  It is a minimum altitude based on the minimum climb gradient given in the SID narrative. 

Sorry they didn't understand the problem.  Part of the problem is that Navigraph has gone through many years of pain and suffering to provide PMDG SIDSTARs in a very old format that is obsolete.  For that reason alone I am willing to cut them some slack.  They really don't understand the nuances of the old format, which I discovered working with them over the years.  The other problem that occurs often is an incorrect turn in the wrong direction to a fix after crossing a radial.

Just fixup the file yourself and keep a copy for pasting on each new cycle.

 

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OK. Make sense now. Appreciate your help. I will make changes you suggested. 

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Here the real, objective truth:

Real-world values which come from the PMDG dataset (Jeppesen source) - with or without displaced thresholds, that´s not important. The coordinates are from the center-line (begin/end):
Rwy 05L = 53.34755556, -2.28776389
Rwy 23R = 53.36131944, -2.25928056
Fix D053A = 53.36235556, -2.25713889

Now, I have calculated the heading (true) between the points 05L -> D053A and 23R -> D053A:
05L to D053A = 50.991°
23R to D053A = 50.968°

You see, the values are identically - there is no reciprocal value, which would indicate that the waypoint is behind the DER. Further calculation, the D053A is approx. 600ft AWAY!! from the DER.

All this has nothing todo with the procedure-file or the coding, it´s a simple calculation and everyone can check it ... ok, its more complex to do this, but it´s the only VALID!! way to show that the waypoint is correct and therefore the procedure is correct ... I´m curious about the new answer ...

Cheers,

Richard

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That is interesting.  I trust the numbers and won't bother running it through my geodetic calculator. Thanks.

I need to come back and look at this again and figure out why at this particular location such an errror in the PMDG FMS occurs and not anywhere else where we have similar departure altitude constraint waypoints.

Richard please solve one puzzle for me:  How is the waypoint for the at or above 760 altitude constraint fixed where it is in your navdata?  All I gleen from the charts does not put it this close to the departure end of the airport.  I checked the minimum climb gradient given on the obstacle chart and used that to come up with my estimate of it's location a little further North at about 53.376 rather than 53.362?  I assume the waypoint is presented in your source data as a lat/lon location?

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Hi Dan,

yes, the D053A is defined terminal waypoint in the Jeppesen database with lat/lon (53.36235556 / -2.25713889) ... it´s a "unnamed, charted intersection" and therefore the reference to MCT/032/0.4 (that comes from the Jeppesen source too as "recommanded navaid"). Hope that helps!

Cheers,

Richard

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