Makerwy's CYUL

[srcooke]

Hello Pete,

 

I'm having an issue with the attached AFCAD where Makerwys is reading in the Magnetic Variation as +15 rather than -15.

 

Opening the file with ADE indicates the magnetic variation in airport properties as set to -15.00.

 

 

 

 

The makerwy's R5 output:

    Line 17940: CYUL,0061,45.461071,-73.764999,118,27.570,11020,109.30BDG,213,15.000,45.472202,-73.750420,0,,
    Line 17941: CYUL,0062,45.457706,-73.741280,118,27.610,9526,110.50BDG,213,15.000,45.467323,-73.728668,0,,
    Line 17942: CYUL,0241,45.476940,-73.716057,118,207.610,9526,110.50BG,213,15.000,45.467323,-73.728668,0,,
    Line 17943: CYUL,0242,45.483334,-73.735840,118,207.570,11020,111.90BG,213,15.000,45.472202,-73.750420,0,,
    Line 17944: CYUL,0280,45.463448,-73.738625,118,252.610,6500,0,200,15.000,45.463078,-73.751328,0,,

CYUL.zip

[Pete Dowson]

I'm having an issue with the attached AFCAD where Makerwys is reading in the Magnetic Variation as +15 rather than -15.

 

Makerunways won't make a special case for CYUL. It ca only deal with the data it gets. It certainly gets -15 for CYUL with default FSX scenery as you can see from the log:

 

Airport CYUL :N45:28:04.9911  W073:44:29.0003  118ft

          City Name="Montreal"

          Airport Name="Montreal-Pierre-Elliott-Trudeau"

          in file: Scenery\0301\scenery\APX28150.bgl

 

          Runway 6L/24R centre: N45:28:19.9897  W073:45:01.5005  118ft

              Start 6L: N45:27:41.3109  W073:45:52.2715  118ft Hdg: 42.7 true 

              Computed start 6L: Lat 45.461105 Long -73.765027

              Start 24R: N45:28:58.6685  W073:44:10.7280  118ft Hdg: 222.7 true 

              Computed start 24R: Lat 45.483330 Long -73.735812

              Hdg: 42.670 true (MagVar -15.000), Asphalt, 11020 x 200 ft

              Primary ILS ID = IUL

              Primary ILS: IUL  109.30 Hdg: 43.0 , Flags: GS DME BC "CAT II ILS/DME 06L"

              Secondary ILS ID = IZZ

              Secondary ILS: IZZ  111.90 Hdg: 222.7 , Flags: GS BC "ILS 24R"

              *** Runway *** CYUL0061 Lat 45.461105 Long -73.765030 Alt 118 Hdg 58 Len 11020 Wid 200 ILS 109.30, Flags: GS DME BC

              *** Runway *** CYUL0242 Lat 45.483330 Long -73.735809 Alt 118 Hdg 238 Len 11020 Wid 200 ILS 111.90, Flags: GS BC

          Runway 6R/24L centre: N45:28:02.4968  W073:43:43.4997  118ft

              Start 6R: N45:27:29.1306  W073:44:27.5004  118ft Hdg: 42.8 true 

              Computed start 6R: Lat 45.457775 Long -73.741412

              Start 24L: N45:28:35.8629  W073:42:59.4993  118ft Hdg: 222.8 true 

              Computed start 24L: Lat 45.476948 Long -73.716092

              Hdg: 42.810 true (MagVar -15.000), Asphalt, 9526 x 200 ft

              Primary ILS ID = IOA

              Primary ILS: IOA  110.50 Hdg: 43.0 , Flags: GS DME BC "ILS/DME 06R"

              Secondary ILS ID = IMQ

              Secondary ILS: IMQ  110.50 Hdg: 222.8 , Flags: GS BC "ILS 24L"

              *** Runway *** CYUL0062 Lat 45.457775 Long -73.741409 Alt 118 Hdg 58 Len 9526 Wid 200 ILS 110.50, Flags: GS DME BC

              *** Runway *** CYUL0241 Lat 45.476948 Long -73.716095 Alt 118 Hdg 238 Len 9526 Wid 200 ILS 110.50, Flags: GS BC

          Runway 10 /28  centre: N45:27:47.4982  W073:45:07.9989  118ft

              Start 10 : N45:27:46.0404  W073:45:55.3873  118ft Hdg: 87.5 true 

              Computed start 10 : Lat 45.462780 Long -73.765854

              Start 28 : N45:27:48.9235  W073:44:20.6123  118ft Hdg: 267.5 true 

              Computed start 28 : Lat 45.463612 Long -73.738586

              Hdg: 87.510 true (MagVar -15.000), Asphalt, 6979 x 200 ft

              Primary ILS ID = IDO

              Primary ILS: IDO  110.10 Hdg: 88.0 , Flags: GS BC "ILS 10"

 

and the consequent R5:

 

CYUL,0061,45.461105,-73.765030,118,57.670,11020,109.30BDG,200,-15.000,45.472218,-73.750420,0,,

CYUL,0062,45.457775,-73.741409,118,57.810,9526,110.50BDG,200,-15.000,45.467361,-73.728752,0,,

CYUL,0100,45.462780,-73.765854,118,102.510,6979,110.10BG,200,-15.000,45.463196,-73.752220,0,,

CYUL,0241,45.476948,-73.716095,118,237.810,9526,110.50BG,200,-15.000,45.467361,-73.728752,0,,

CYUL,0242,45.483330,-73.735809,118,237.670,11020,111.90BG,200,-15.000,45.472218,-73.750420,0,,

CYUL,0280,45.463612,-73.738586,118,282.510,6979,0,200,-15.000,45.463196,-73.752220,0,,

 

So I think you need to check your addon scenery for CYUL. Have a looks at the runway magvars.

 

Pete

[srcooke]

Will try and look deeper Pete, thanks.

[Pete Dowson]

Will try and look deeper Pete, thanks.

 

I've looked at your BGL with both ADE 1.65  (same as your pic), and also with AFX 1.10.

 

Interestingly, AFX shows the airport Mag Var as +15.00 whilst ADE shows it as -15.00. Evidently there must be two places where this is recorded. AFX evidently gets it from the same place as MakeRunways -- a 32-bit floating point value at offset 36 in the airport structure.

 

Both programs do give -15.00 Mag Var in each of the ILS navaid entries.

 

Maybe FlyTampa can explain this discrepancy

 

Pete

[srcooke]

I used ADE's raw data view and noted that all other entries for runway's etc other than the airport contained +15 figures.

 

Having de-compiled to xml the figures were adjusted and the file re-comipled to .bgl where upon all the figures look correct.

 

Makerwy's and indeed AFX still see a +15 variation so no idea where it's coming from.

 

Will try FlyTampa and thanks once again for the pointers.

[srcooke]

Established ADE seems to be using a reverse implementation at least in the entry dialogue for the magvar.

 

Setting a +15 figure in the airport dialogue then compiling leads to a correct -15 output :(

 

The AFCAD in question seemed to have a mix of +15/-15 figures that added to the confusion.

[Pete Dowson]

Established ADE seems to be using a reverse implementation at least in the entry dialogue for the magvar.

 

Setting a +15 figure in the airport dialogue then compiling leads to a correct -15 output :(

 

That is truly weird. I'll see what ADE makes of the default ...

 

... YES! ADE shows +15.00 for the stock FSX CYUL airport too -- both ADE 1.65 and the earlier 9x version.

 

So, it looks as if it is a bug in ADE -- and presumably the FlyTampa airport was built with, or at least modified, with ADE. Best report this to both sources, please.

 

Pete

[srcooke]

Having raised the topic with ADE their implementation is correct and thanks to Jim for his prompt response.

 

The FSX SDK details:

 

magvar (optional)

Magnetic variation at the airport to True North in degrees.

-360.0 to 360.0 floating point value. Default = 0.0. East magvar is negative, West magvar is positive.

[Pete Dowson]

-360.0 to 360.0 floating point value. Default = 0.0. East magvar is negative, West magvar is positive.

 

That's truly weird. I still think, for consistency, the display ADE shows in Airport Properties should show it in its normal form, -ve West. The fact that it's reversed in the binary is really just an encoding matter (probably down to an original error by a Microsoft programmer). By showing it as ADE does, with not even a warning that it is opposite, you are bound to come across implementations, like FlyTampa's, which get it wrong! I wonder if it is wrong in all FlyTampa sceneries? And how many other add-on scenery makers using ADE?

 

So, next step, tell FlyTampa they have it wrong?

 

Pete

[srcooke]

There is actually a user posted correction on the FlyTampa forum.

And here is an extract from chapter 15 of the FAA Pilots Handbook:

 

If the variation is shown as “9° E,” this means that magnetic north is 9° east of true north. If a true course of 360° is to be
flown, 9° must be subtracted from 360°, which results in a magnetic heading of 351°. To fly east, a magnetic course of
081° (090° – 9°) would be flown. To fly south, the magnetic course would be 171° (180° – 9°). To fly west, it would be
261° (270° – 9°). To fly a true heading of 060°, a magnetic course of 051° (060° – 9°) would be flown.

 

Remember, if variation is west, add; if east, subtract. One method for remembering whether to add or subtract variation
is the phrase “east is least (subtract) and west is best (add).”

 

 

I think that concludes my re-education on the topic this week :)

[Pete Dowson]

There is actually a user posted correction on the FlyTampa forum.

 

Does the error apply to all FlyTampa airports, though? I'd better check my Copenhagen ... No, seems okay. Phew.

 

 

And here is an extract from chapter 15 of the FAA Pilots Handbook:

 

Yes, so?  ADE is still showing it incorrectly because the FS convention has always been, and still is, -ve = West, +ve = East. So a variation of 9E is +9 whilst 9W is -9. 

 

Have you reported this to ADE support?

 

Regards

Pete

[srcooke]

Yes Pete I have: Mag Var Reversed and that is where the reference to the fsx sdk came about.