Despite the fact that, in UK, Police Air Observers undergo a formal aviation course and wear an Observer's brevet on their flight suits, they are officially passengers, as per the PAOM.
I think this belittles their duties and capabilities: those I have had the privilege to serve with in the past have been every bit as professional 'aircrew' as some that I knew in a distant military life.
Cynics might say say that if PAO were aircrew, they would be bound by CAP371 FTLs and that this would put an unbearable strain on police peopling. ('Manning', for the un-PC!)
This has all been said before....see previous threrads,wherever they've gone to.