I think it is very important to make a distinction here between technical knowledge and that fuzzy thing that is sometimes called “airmanship.” Given the right person, I don’t think that it would be that hard to make a low time pilot reasonably proficient in the relatively narrow set of tasks that are required for a particular aircraft type and a particular operation. As long as everything goes according to script and the problems fits within whatever has been anticipated and covered in the manual then they’ll probably do fine when crewed with an experienced Captain. I see two potential problems. When that Captain himself has issues (these guys are out there), then the low-time FO may not know enough to know the Captain is having issues. He may just think the guy has a few quirks and doesn’t feel comfortable speaking up. I think some of this may have come into play with the Ethiopian crash. Next, flying doesn’t always go according to the script, and when you get off script it may not be obvious what the answer is. It has been said that good judgment comes from experience and experience comes from bad judgement. In the old days, a newish pilot would go out and excercise just enough bad judgement to hopefully gain some valuable experience and would do so in something that wasn’t carrying 100+ passengers. What I’m saying is no matter how well you know the aircraft, procedures, or regulations, there is always an element of knowledge that simply comes from doing the job for a number of years.