I found this first hand account in 'Cheerful Sacrifice - The Battle of Arras 1917' by Jonathan Nicholls (Leo Cooper 1990) - a book to my liking as it shows the battle from both sides of the line. I hope it is of interest.
"The weather was clear and soon there were planes about. We saw the usual dog-fight which regularly happened in the afternoon and saw an English plane fall out of the sky, and then another one which somersaulted over and over before hitting the ground about a kilometre away....Unfortunately it was one of ours, with the well known
Leutnant Frankl, with his 'Pour Le Merite' and Iron Cross, 1st and 2nd Class on his chest, lying still in front of us. Solemnly we went back to our village."
Musketier Herman Keyser Res Rgt 84.