Unusual contrail over UK
Question for London ATCO's:-
I was flying in and out of Heathrow today and with the clear blue skies could see what looked like a 'B' shaped contrail between London and TNT being formed over and over again.
It was at a good height, >FL400 and was in the air from around 11am until at least 1:30pm.
Do you guys and girls know what aircraft it was? What were they doing?
Or can't you say?!
Thanks.