According to X-Plane11 readme file, “a custom waypoint file is supposed to reside in the Custom Data folder”.  I copied the “ earth_fix.dat file” (containing new fix points) into the Custom Data folder yet both the GPS in X-Plane11 and loading the flight plan containing these fixes into Pilot2atc do not show the new fixes.  This method has previously worked in X-Plane10.  What am I doing wrong?

You need to create a user_fix.dat in the Custom Data folder using the proper format.

See here for more info:

https://forums.x-plane.org/index.php?/forums/topic/166039-create-custom-user-defined-fix-in-x-plane-11s-new-g530-gps/

https://developer.x-plane.com/article/navdata-in-x-plane-11/

Thanks so much; exactly the info I was searching for although it may take a while for an 85-year-old to decipher.  But, again, thanks for getting me back on track!

I read your recommended method (“easiest way to create a user_fix.dat file”).  The attached Notepad file is the result of first creating a plan from within the default FMS which contained all the ICAO and waypoints already stored in the XP11 FMS, saving it, and then modifying it to include new waypoints (ABCDE, and EFGHI) and re-saved the modified/butchered(?) file.  Loading the new file into the GPS of a vflyteair Arrow III ignored the new waypoints.

Have I incorrectly entered the new waypoints and if so, is there an example of the correct format?

Thanks again for your much-appreciated help!

Oops;  could not attach the file with a different extension!

The following are to two new waypoints:

43.4058967 -88.56818369 EFGHI ENRT ZZ

43.4351957 -88.6360486 ABCDE ENRT ZZ

Considering all the effort X-Plane put into the (impressive) FMS one would think they would make available definitive instructions on how to enter custom (/lat./long) waypoints.  Following the instructions in the FMS manual for data entry does not work as expected.  I’ve researched numerous sources without success.  Could my FMS version be out-of-sync with the instructions available?  Or, does someone on this site know the exact required data and FMS key entry?

The official file specification is here: https://developer.x-plane.com/wp-content/uploads/2016/10/XP-FIX1101-Spec.pdf

 

Here's another thread on the matter: https://forums.x-plane.org/index.php?/forums/topic/112134-how-to-add-a-custom-fix-with-latlon/

Thank you Bjoern! for the excellent resources.  Hopefully, as I study all that's available and understand the exact keystroke input/sequence that the FMC demands, I'll be able to enter a flight plan!

Spoiler

 

 

You're welcome, but I can't help you any further as I never tried to add custom fixes myself.