Originally Posted by
TowerDog
Not every airline is the same, Major, Minor whatever.
Seniority and recommendations from Captains you have flown with over the years may make a difference:
If you are sharp, your internal file should have good letters, if you are a dork the file will be full of “Do not, ever upgrade this guy, (girl) under any circumstance”.
You have to prove yourself every day in this line of work, in both seats, and even in all 3 seats if you fly long haul.
I'm curious what US carrier requires "letters from Captains you've flown with" to qualify for upgrade. I'm not aware of any, at least not to become a line Captain. Now, if you're talking about becoming an instructor, that's another matter.