On several dates, my ground station received some airborne operational status ADS-B messages (TC=31) where the version number was reported as
3. As far as I know, the only valid versions are
I don't think it was just a garbled reception because
- I received more than 500 messages of the same type, all reporting
3as the version number.
- The messages came from three USAF aircraft of the same type, KC-10A Extenders.
Here is a sample message, in raw form:
The dates on which I saw the messages:
The aircraft associated with the messages:
- ICAO AE020E, registration 79-1948
- ICAO AE0212, registration 82-0193
- ICAO AE022E, registration 86-0037
What's the most likely reason behind these messages having this (AFAIK non-existent) version number? A test? A misconfigured piece of equipment (it strikes me as unlikely that the version number can be set to 3, but maybe I'm wrong). Is it a bug in the decoder I'm using?
[Edited 2019-02-16 to include other aircraft I've received the anomalous messages from.]