Variablepitchp
The “1500 hour rule” or more accurately the requirement to hold an ATR (ATPL) actually came into law as result of the AIRLINE SAFETY AND FEDERAL AVIATION ADMINISTRATION EXTENSION ACT OF 2010 and the Colgan 3407 accident. Arguably, since in that accident neither pilot had less than 1500 hours in any event. Age discrimination isn’t an issue beyond the age requirement to hold the licence, which in itself doesn’t discriminate.
The clue is in the name.
Airline Transport Pilots licence. To fly in that capacity, it is not unreasonable to hold that licence.
When the last advert you saw that said ‘X years experience required’? Likely a while ago as that practice is now banned.
I don’t think I ever did since age wasn’t the requirement. Now substitute the unit of measure from “years” to “hours” and I think a great many did and still do.