They only popped up back end of last week. Since the initial 1 x UAL 744 it is now 2 (PMI / TFS), Air Transat 330's and Omni Air 777 (BCN) also thrown in today...it's a growing list...all one thing in common...UK to Spain empty and returning full.
Could it be another airline / tour operator involved ? It'd be devastating if it were MON
