It doesn’t. Age 21 for an ATPL in the rest of the world has not had adverse affect on overall safety of operation. I’ve trained new pilots with RATPLs with some 300 hours of total time. Of course that was a light twin, the B737NG. Yes had to be quick to react when a hard landing was in our immediate future. But then again I was a training captain on the 757 too.

IMO, 121.346 nothing more than a knee jerk reaction, did nothing to enhance safety of operation. COLGAN accident was a result in Non-conformance training and checking. Line training in other parts of the world is based on a minimum number of sectors rather than number of hours. It seems that US carriers’ training is reminiscent to the puppy mills that flight schools were referred to… Train em and get em out on the line.