How old is too old to fly?

James M. Knox wrote:
There is no question that (percentage-wise) older pilots have slower
reaction times than youngsters. Cognitive skills also decrease with
age. OTOH, pilots with more hours tend to have more experience (and
hopefully better judgement). For some time these things probably offset
each other (or even show an improvement).

Reminds me of an old story...
Airliner flying along, greybeard in the left seat, wet behind the ears
FO in the right. A chime begins to sound, followed by a flashing light.
The anxious FO looks over at his Captain and observes him winding his watch.
Incredulous, the FO stammers, "Captain, we have a situation to deal
with. Why are you winding your watch?"
To which the wise man replied, "I never killed anyone winding my watch
before."