Lear guy,
The failure rate cannot be simply explained by one single reason in the courses. The decision to cut a pilot is made after carefull consideration and is not one bad Sim. There have been pilots fail the JCAB check and be kept on and retrained as well as guys that won the free trip home, it's often about the attitude of the candidate. At the end of the day if the ANA instructors don't think that you will pass the JCAB check, you will be cut and that's it.
I do tend to support the FOs' here to be upgraded as opposed to DECs' but as you point out there is a demand. In my experience with ANA the DEC window is not open for very long. It was available at the initial set up and now after the division of AJX/AJV and the rapid demand for expansion. It is great to get experienced guys, but ANA are finding it difficult to get well qualified DECs' although we have a lot of very experienced FOs' and it is a bit of rub for them to have to hold the hand of an inexperienced guy especially for this type of flying.
Finally, as I understand it the demand for pilots is mostly in AJX right now, the passenger side.
Gambate ne