add: Changelog for 2406b (#119)

* add: Changelog for 2406b

* refactor: Clarify when fault presented itself

* Update 2406b.md

docs/changelog/2024/2406.md

@@ -12,8 +12,6 @@ Additionally, we now have Standard Route Clearance maps for each aerodrome, as w
 
 ### BAY Sector
 
-!!! info "This change will be made public on 13 JUN."
-
 References to waypoint `NOBAR` and associated procedures amended to now reference waypoint `DODKU`.
 
 

docs/changelog/2024/2406b.md

@@ -0,0 +1,25 @@
+---
+  title: Cycle 2406b (13 Jun)
+---
+
+--8<-- "includes/abbreviations.md"
+
+As a result of a minor oversight, errorneous data was exported to production. This rush revision fixes these errors.
+
+## Fixes
+
+- A previous testing version of the consolidated STD RTE map made it into the production build. This contained routes from Cycle 2404, which referenced waypoints no longer present in our airspace. This presented several errors to the user. This file, not intended for public consumption, has been removed.
+- WPT `BIDEV` replaced by `IDRUX`, which is on the RWY 20 RNP Z at NZCH. This waypoint wasn't changed in the dataset, thus the application referenced a WPT no longer present in our airspace. This presented two errors to the user. 
+- WPT `BATAT` and `ADGIN` removed. These waypoints weren't contained in the dataset, thus the application referenced WPTs no longer present in our airspace. This presented four errors to the user.
+
+## Why did this occur?
+
+vatSys can use two types of defined data - either Navigraph or locally-defined data. The NZZC and COD datasets are designed so that all necessary data is contained within the dataset files (`Airspace.xml`), and will refer to the Navigraph dataset if that data isn't present as a fallback. This ensures that Navigraph is **not** a pre-requisite for using vatSys.
+
+For the NZZC dataset, the locally-defined data reference is sourced from the New Zealand Air Navigation Register. For the COD dataset, the locally-defined data reference is sourced from Navigraph. This is due to VATNZ's airspace spanning multiple FIRs, with consolidating that information manually being a difficult task. 
+
+The reference Navigraph dataset that was installed in the test environment was a much older version, sitting at Cycle 2304. Therefore, if procedures were referencing a waypoint that had been removed in a subsequent cycle, vatSys would fall back to the Navigraph dataset and resolve that waypoint. 
+
+As the COD dataset can only be updated after the latest cycle release from Navigraph, work on the COD dataset began not long after Cycle 2406 was released. After the Navigraph data was updated the previously available fallback values were no longer present, causing the application to produce alarms.
+
+Going forward, our pre-release testing will be run in a clean vatSys environment, ensuring that we have the most recent data possible. Whilst not completely mitigating the potential for erroneous data, it is the most pragmatic solution.