There was inference from Running In that RAF crewmen don't do planning or Nav. They do. Very much so.
They also accompany the pilots on IF trips, often with little to do, but learning enough about it and doing enough that should they end up with 2 junior LCR stick-monkeys, about to pull up through cloud into an airway, he or she could say no and come up with a sensible plan B. This is after they've quickly selected all the necessary, nearest and relevant navaids and freqs to further reduce the capacity required of the front enders. And once they're finally preparing for an approach, correcting them when they've calculated and selected the wrong MDH. I've heard it on verygood authority that CHF crewmen don't even bother their arse to go on IF trips.
It's not just ramp up, ramp down and counting backwards missing out numbers.