The SERCO observer jobs you refer to are observer instructor jobs on 750 NAS. I know this because I completed the basic observer course at 750 NAS last year. Since you are asking about what these jobs involve I can tell you you're not qualified for it. SERCO are looking for ex-RN officers who were qualified as observers.
The FAA observers are tactical helicopter controllers. They are all qualified in either the ASW, AEW (bagger scum) or ASUW (lynx twats), naviagating their helicopters over open ocean and many other wonderful things.
It you fancy becoming an observer check out the RN web site (you must be under 26yrs).
Hope this helps !!!!!!!!!!!!!!
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I'd rather be in Florida (honest !!!!)