I think you're all looking at it from the wrong way.
Say you have a confirmed job offer from an airline with a start date. A condition of this job is that before the start date you undertake, at your own expense, an A320 type rating.
This is related to your current employment - ie, the new job. It's not speculative- you're not doing it to enable you to get new employment. You've already got the new employment and it is an absolute requirement if your employer directs you specifically to undertake that training. Therefore, yes, it should be tax deductible.