Donkey's years ago , whilst descending through FL 170 over Southampton, we passed a corrugated iron garden shed ! It turned out that there had been a mini-tornado over Portsmouth that afternoon which had sucked it up to great heights. It was only later that we realised what a very narrow escape we had had
That must take a prize ! Just thinking about it now , gives rise to '' Do we tell the boss / wife / CAA ? 'cos no one will believe us '' .
Must be some more ' unusual airborne object ' stories out there ....