(content from this post by Peter King)

NavData goes through the following lifecycle:

  1. Jeppesen has an ongoing process of capturing NavData into a master worldwide ARINC 424 database.
  2. Each data cycle, Jeppesen sends a copy of the Master ARINC 424 data to Garmin for avionics-specific processing.
  3. Garmin filters the NavData down to elements that can be implemented on a particular family of avionics (e.g., the G1000). This filtering process is strictly regulated.
  4. Garmin then sends the avionics-specific data set back to Jeppesen for distribution.
  5. Jeppesen distributes the avionics-specific data to customers for upload to their avionics.


Many Garmin WAAS navigators (including G1000s) appear to have a bug that causes them to function incorrectly if the NavData does not specify a VDA for an LP approach. This bug is severe enough to warrant a Special Airworthiness Information Bulletin, which I cited in my first reply.

Until the WAAS navigators get a software update that fixes this bug, Garmin will filter out all RNAV approaches that trigger this bug. According to Garmin Service Advisory 1372, Rev. A, the entire approach is deleted, not just the LP level of service. This is likely due to restrictions on how Garmin is allowed to modify the NavData when they massage it.

There appears to be one and only one version of each NavData cycle for all G1000s (regardless of whether they have WAAS or not).

So, the fact that your G1000 does not have WAAS is not the problem, and what Garmin Customer Support said does not make sense. The problem lies with all the other WAAS-enabled G1000s that have the bug. For you to start getting that approach on your G1000, the following needs to occur:

1. Garmin needs to fix the bug in all WAAS G1000s so they can stop filtering that approach out of their database. This means they have to get all the aircraft manufacturers on board to re-certify the new version of software under each type certificate.

OR

2. The FAA needs to publish a vertical descent angle (VDA) for that approach.

OR

3. Garmin needs to produce two versions of the G1000 NavData, one for non-WAAS or upgraded G1000s, and one for G1000s that still have the bug.


Peter King

ATP, MCFI

Bend, OR