I recently enquired about missing ndb overlays from jepps database and received this comprehensive reply but I’m not sure I’m any the wiser! It seems they are saying it’s due to biased dme, but this happens most places? Anyone explain why EGNC is different in simpler terms? A few years ago they used to be in the database if I remember correctly.
I just received the response from our database team. It seems that the approaches you enquired about are excluded from the database as incompatible. See below for the details provided by Jeppesen:
“According to ARINC 424 coding specifications, NDB DME approaches require the associated DME as reference facility in coding. Many of the NDB DME procedures in the UK are using a biased DME (DME reads 0 somewhere other than at the DME navaid) as reference. However, this does not meet ARINC 424 requirements because a biased DME cannot be used as a recommended navaid. Since Jeppesen codes all data according to the established ARINC 424 coding rules, the procedures cannot be added into standard NavData.
Our production team evaluated and checked the publication for EGNC once again and confirmed that it is not possible to code. Therefore you do find one coded procedure only. Charting is different than the required ARINC 424 data for coding and it is possible to create the charts.”
EGTC is the same. Just use the GTN Visual Approach, or an OBS, to follow the same path. You know it’s obstacle safe!
Thanks, but why can it not be done?
It’s explained in the paragraph from Jepp.
Jepp works to a set of standards and its reliability and certification is based on it doing so.
If it breaks those rules it would require a top down recertification process.
As ever, we Brits do things in a non-standard way, that does not fit the certified model, so a choice must be made and, not surprisingly Carlisle, Cranfield and Lydd NDB/DME approaches are sacrificed.
I would make the same decision. It seems perfectly reasonable.
Not really, you are just quoting my original post.
I only have access to iPad gtn sim with database a year old at the moment, but Lydd appears to have an overlay for the published ndb approach, Cranfield has no ndb overlays and Carlisle has one which seems quite different from anything published(!!!), but I recall that it used to have them prior to it shutting for resurfacing etc.
I don’t speak Arinc 424, but was hoping someone could expand on the exact issue.
I don’t see that the above airfields are particularly different from the rest of the uk.
