IAN approaches

[Christopher Low 5,352]

I enjoy making IAN approaches in the PMDG 737NGX when an ILS option is not available (generally because they are easy). However, I have noticed that the glide path in almost all of them is slightly offset from the runway centreline. Is there a reason for this?

[vadriver 247]

Christopher

The lateral path shouldn't be ...... but may seem so due to drift perhaps (seen when visual or checking heading vs track). Is slightly offset seen at 3nm, more or closer & seen against another parameter (as you have no localiser).

But then maybe it's how the sim's magvar influences the lateral data one sees.

The vertical (glide) path can be a tad different due FF/MDA demands etc..

 

Edited January 24, 2023 by vadriver

[C2615 319]

Nav data and Scenery data is different in PMDG's Navdata, runway is defined with 2 end's coord in wpNavAPT.txt, and in scenery runway is defined by center point, length and geo heading, so there would be at least few meters of error.

PMDG's navdata isn't really capable on many IAN function, What I know is it just simulate a extended line form runway rather than based on GPS and waypoint data, so you can't do a NPA with actual offset with PMDG's IAN (you can do one in iFly and Zibo)

[vadriver 247]

@Christopher Low

I guess the OP needs to be a tad more specific about offsets .... where, intentional etc.

1 hour ago, C2615 said:

PMDG's navdata isn't really capable on many IAN function

never seen that but my experience is limited & not recent .... though i understand / appreciate your notes.

[Christopher Low 5,352]

I would need to check to see if any of these approaches have specified offsets, but I think that I have seen this with every IAN approach.

Edited January 25, 2023 by Christopher Low

[787flyer 633]

I thought some IAN approaches do have an offset FAC and that while continuing to use the computed vertical glide path, lateral adjustment to the runway centreline may be needed. I recently flew one in the 737Max into Crotone (LIBC) using a VOR approach with IAN enabled. Runway heading is 346 but FAC is 350 deg.

 

The reason I understand for this is, the VOR navaid may be located off the centreline to the runway as in the case of LIBC where the VOR (CRN, 117.1) is located to the east of the runway and the offset FAC of 350 deg. This FAC is designed to bring you in alignment with the runway by intersecting/crossing through the runway centre line.On this course you are always guaranteed to intersect the runway centreline.