Aviatik
Looking through my (handwritten) notes, it looks like I picked up two different dates at some stage but discounted 6 April (I crossed through this date), believing I'd confused the date of his death with his date of birth.
Going to reference sources at my fingertips:
the A to Z list of casualties in
Casualties of the German Air Service (page 119) shows:
"Preuss, Kasimir von Preussen, Prinz Friedrich Karl Tassilo, Rittm, 6 Apr 93, Klein-Glienicke 6 Apr 17 [21 Mar]" indicating that he had been wounded on 21 March and died on 6 April.
The preamble to RFC Communque No 80 on page 27 of Royal flying corps communiques 1917-1918 states:
"Further reinforcement for the RFC in France this week was the arrival on March 21 of No 100 Squadron, equipped with FE2bs and FE2ds. Lt Pickthorn's victim that same day was Prince Friedrick Karl of Prussia, who force-landed his Albatros scout in front of some Allied trenches. Attempting to reach the German lines, he was shot by Australian infantry and died of his wounds on 11 April 1917."
I recall something appearing in a Cross and Cockade (GB) journal some years back. I'll try and locate it and see if it sheds any light on this.
Graeme