I guess our posts overlapped Vu. When variation is East then it is subtracted from the True heading to obtain the corrected Magnetic heading BUT the true heading is never used in the PMDG NGX since it is modeled only for Magnetic course headings (thus the limitation for polar flights in the FCOM) So the only way to figure this out is to disassemble the AFCAD and check the TRUE course of the runway as well as the localizer beam in the AFCAD. Something must be amiss. Again, I am using default KSEA AFCAD and everything is in sync.

 

Ah! Try this: Place a default 737 aircraft at the start of runway 16L using the FSX world airport menu. Unpause it and note the runway heading on the HSI. Now set Nav1 to the localizer frequency (110.30) and verify that the needle is in the center when you set ECAS to APP. This should be center regardless of your course setting. Localizers only send out one directional beam frequency (VOR transmitters send out 360 frequency variations corresponding to Magnetic course radials and require course tuning). If the needle is not centered then it has been incorrectly coded in the AFCAD and that is what is causing your problem. Doulble check that you are not setting VOR tracking in the MCP instead of APP. That's all I can think of since I am unable to duplicate your problem with NGX

Ok, I will try that and report back. What I did was very simple: clear all weather, program the FMS for a round trip from KSEA back to KSEA via PAE. On the way back, select ILS 16L, arm the approach and do all the necessary steps to execute an autoland with CAT IIb. As I watch the NGX does its sequences, it sets the heading on the MCP to 182 and the air plane lands itself perfectly on the centerline. If I read all the posts right, I should be setting the heading to 163 as the chart specified, and the NGX should do the same, but it does not. Let's see if I sums up: So there may be something crooked here with my ORBX KSEA (or FSX), but else where, I should be using the course as in the approach chart and set it on the course on the MCP?

 

Thanks

Just curious, why would the CRS heading affect the ILS landing? I thought if the LOC is aligned with the runway centerline and you capture it, then you be lined up on the centerline regardless of CRS.

 

I don't have access to my sim right now, but does the Ray Smith KSEA fix it? http://library.avsim...cad&DLID=146102

The Autopilot does not know what the inbound course is, and the ILS signal doesn't tell it. All the Localiser tells the AP is how far left or right of the LOC beam it is. Without knowing the beam direction it doesn't have enough information to follow it properly. You must select an inbound course so it has this information. One or two degrees off won't make that much difference, the aircraft will land slightly to one side of centre, but try using a course 180 degs out, the initial turn to intercept may be in the opposite direction.

 

This is exactly what would happen in the real world too if you mis-set the inbound course.

Good airmanship practice is to set the CRS heading, just in case you have to single channel A/P land instead of a dual channel Autoland. If the course setting does not match and at the last few moments, the Autoland disengages for whatever reason, it would be nice if the CRS heading agreed with the Localizer as in real life.

It's more than just good airmanship, it's essential. Also, if autoland disengages, the AP won't follow the selected course. It will go into a heading mode, so the LOC CRS won't have any effect.

I feel like I hijacked this thread somewhat with my question on setting CRS, my apologies. Anyway thanks for the responses. Very interesting thread!