It does sound like the DS solution but it's a lucky man who gets that kind of deal. Flying pay is only reduced or withdrawn once the PVR on JPA has been actioned by your desk officer or Adjt/MCM. So it pays to be in a. It with terrible admin!
I'm not saying that this is right but it does happen. One thing's for sure, being paid 50% flying pay when you're on Ops is just rude. Not being paid any flying pay whilst on Ops is outrageous!