Crossing the antimeridian

[MdMax]

Hi all !

Today I decided to cross the "180th meridian", so I made a flight from Eareckson Air Station (PASY) to Adak Airport (PADK).

Routefinder told me to take this route: PASY DCT WALLT R451 CHIKI DCT PADK. I know, that's very lousy flight planning.  

But I found several bugs on the navigation display and the HSI on the PFD.

As you can see on picture 2, on the PFD, the NAV source was FMS, the course 149, but on the HSI, the arrow was showing a course like 184. So I decided to use only HDG and not NAV for this short flight.

Later, on picture 3 you can see that the lines from PASY to WALLT and from WALLT to CHIKI are correct, but the line from CHIKI to PADK is false and is crossing my route... CHIKI's longitude is something like 177.108 degrees east and PADK's longitude is 176.627 degrees west.

On picture 6 you can see that I removed WALLT and CHIKI on my flightplan. But the FMS was still unable to draw a correct line between PASY and PADK. The distance on the FMS (234NM) and the heading (85°) were correct.

After I crossed the antimeridian, about 120NM from PADK, there was again a line on my navigation display, but this line was east from PADK, far from my route, you can see this on picture 7.

I was able to land safely on Adak Airport using the ILS for runway 23 (108.90) but for now you should not trust the FMS for crossing the "180th meridian".

My system:

- OS: Ubuntu GNU/Linux 10.04 64-bit (with 32-bit libraries from 11.04)

- GPU: GeForce 8800GT with 512Mb DDR3 (driver version 270.29)

- CPU: Intel Core 2 Duo E8400 @ 3.00 GHz

- X-Plane 9.69 (all other plugins removed)

- CRJ-200 version 1.1

- United Nations livery: http://forums.x-plane.org/index.php?app=downloads&showfile=13555

- Regional formats: English (United States): http://forums.x-pilot.com/index.php?topic=2168.msg21163#msg21163

Happy flying !  8)

[Japo32]

Thanks! we have to check this out.. and also north and south pole!!! hahaha.. Well just kidding.. Ok.. Philipp has to take a look at this.

Thanks!

[philipp]

Hi MdMax,

I analyzed your flight and found the following: The FMS is doing perfectly right, just the MFD is drawing utter nonsense.

If you just leave FMS mode on, the autopilot will fly the flightplan exactly as expected, and guides you safely over the 180° meridian and to the destination airport.

You just have to trust it and ignore the MFD, which will be showing a wrong track.

However, using the MFD in HSI mode will show perfectly okay.

Thanks for the detailed bug report. I will see what I can do to the MFD projection.

Philipp