Couple of years ago, I ferried a 747-200 for "desert-retirement" to Mojave.
We pilots were both over 60... the flight engineer was a hair over 65.
Incredible how senile crewmembers are permitted to be, by ICAO and FAA..
That is "outside" airline operations, such as ferry flights.
xxx
The flight engineer hearing-aid was wired to the hot battery bus.
My heart pacemaker was on the essential bus.
Other pilot tapped his white cane to find his way to the flight deck.
But the Jeppesen charts we had were in the Braille edition.
xxx
Happy contrails