Casino (and anyone else interested),
To crossover from NCA to commission you need to have completed one productive tour. You don't need permission but you do have to get a form signed by your boss. This is still worded as a request to apply however they cannot stop you as such, it is really so ensure they are aware you are applying.
After that you go to your station admin section who pass you onto the local careers office, from which point you get treated exactly the same as all other applicants, ie. AFCO presentation, interview, OASC etc.
The biggest difference is that once you get to OASC they will have been sent a copy of your annual assessments and flying assessments, which will obviously play a large part in their final decision.
The general boarding officers do not see these (I have been reliably informed), however the President of the Air Board, who efectively makes the selection decision does, therefore if you are a cr@p SNCO or WSOp, then you will not be selected for commission. However, if you are maybe borderline but are a good SNCO and above average at your flying job, this can ensure you get selected over another direct entrant who is borderline as you will be a known quantity and therefore probably more worth 'gambling' the few pounds it costs to train an officer.
As regards crossing from commissioned to NCA, I would think this would be nigh on impossible as it would be seen as a step backwards in terms of career progression. There would probably have to be some other conditions. I do know of a couple of guys chopped during pilot training, already commissioned, who were sent back to OASC to look at a rebranch and they ended up resigning their commissions and becoming NCA.
Also the chance of crossing over from another branch to pilot is very rare, although it has happened a couple of times. if you really want to fly in the RAF, try for as long as you can for pilot or NCA. Don't forget WSO too, there will still be a job for thise boys and girls for a good few years yet!
Good luck to you and feel free to PM for any more info.
The Glove
When you contact the AFCO, ask for details of the Engineering Liaison Team at Cranwell. They are set up to tell people like you about Engineering Officer roles and can arrange visits to Cranwell, which I believe also includes a trip to Waddington or somewhere else nearby. They can also advise on Uni sponsorship schemes, Welbeck Sixth Form College (or whatever it's called) and other nuggets of priceless info for someone like yourself!
Any probs getting the number PM me and I'll have a dig for you.