Yes..that's a good point, basing, holidays e.t.c. should be based on date of joining - it's the only fair way really.
But command positions.... well we have a few things to consider here...
Commanding an Airbus/Boeing - whatever, is a
learned skill.
People learn at different rates. A bright young thing who has been through RAF/BA selection will have demonstrated the ability to
learn quickly - that's all. That's what the tests are about.
What several people are eluding to is
wisdom:
'..experience and knowledge together with the power of applying them.'
Oxford English Dictionary
Now..
That's the quality that we're after.
How are you going to measure that?
Is age nothing more than a good starting point?
Has it got very little to do with it?
Any ideas?