Thanks for your replies. If I were the LHR Tower ATSA though I would feel happier if I had done a full Met Observers course though rather than an 18 hour abridged version, even if it cost more money just for my own peace of mind. Does the 18 hour course give the participant a recognised qualification?, and if there were a "problem" and the observation was a factor how would the observer stand if they had not done a full Met Observers course.