RADAC,
If your Dad is the holder of the AFM and his birthday is 29 June 1923, then he IS the ultimate professional - let there be no doubt of it!
In those days, when one hit 47, you stopped flying and lost your flying pay. Many ex-flyers went air traffic. Your dad used to say: 'Everytime they tell me I've got to go air traffic, I get this ttttt erible stut stut stutter'.
Old Duffer
PS: and he's good egg to boot