Yes but the point is that if someone did make a legal case against them they would have to defend their assertion that it takes longer or is harder to train a 42yr old than a 18 - 29yr old as advertised for. They couldn't just claim it without evidence that was strongly related to the job advertised for.
I cannot see where or how that evidence could be found.
Any defence relating to length of service post training would be severely undermined by examination of the turnover rates of pilots and the average length of service thus existing.
You can't just say well we'll just bin any over 30 CVs anyway or bin them at a later stage without giving a reason. Because if just one of those over 30 CVs happens to be black, gay, catholic etc and makes a claim then you are going to be standing up with nothing to say at a tribunal for discrimation upon which there is no limit for damages or compensation awards.
So your HR Manager won't let you just bin any CVs.
Cheers
WWW