I believe some countries in Europe require at least one of the pilots to be below a certain age to fly in their airspace.it could be 62.
France comes to mind
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Indeed this is the case in France, as a result of Air France pilot unions insisting that their pilots should be allowed to retire at 60 on huge pensions.
Just about every other pilot in France would like to carry on working until we drop, but unfortunately we are outvoted!