That I do agree with. It is ridiculous really that an FI is only paid whilst airbourne, since to the job properly takes a lot more than just the flying.
I have lost count of the hours I've spent sitting in briefing rooms or answering the bl***y phones or just doing general administrative duties. Briefing pre and post flight is fine, but sending hours explaining the intricacies of met or another subject and not getting a penny for doing it?.....
It would be far fairer to pay an houry rate from turn up time to leaving time, but most schools will never do it. Why, because they can't afford it, so see my earlier points about why it's rubbish working for the vast majority of schools in the UK.
There are good schools out there, they are just in the minority.