D-IADV TCAS messages?

[Aireps]

Hello,

D-IADV, from EHAM to EHGG today Feb 20, and currently (11Z) doing airwork near EHGG (PH-LAB about 10 NM in trail continuously) is transmitting lots of TCAS messages that appear to be empty. A small sample of today's messages (there were many more):

Code: Select all

3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 10:08:20 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 10:08:32 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 10:08:40 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 10:08:53 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 10:09:10 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 11:07:47 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 11:08:03 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 11:08:15 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 11:08:28 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 11:08:44 UTC
3E17AB D-IADV TCAS Alert - no data [tca] at 17-02-20 11:08:57 UTC

The transmission of empty TCAS messages by D-IADV is going on for many months now. Any ideas about the background of this?
I haven't seen any other aircraft doing this.

Cheers