Creampuff, check your maths: you did 18 yrs
Old Fella:
I joined the RAAF the same year the first A models arrived (1958)
So he was in 30 years before you started, and the 707 arrived in 79 or thereabouts, giving him at least 21 years, maybe more, depending on how long he stayed after 707 arrived.
He probably retired before you grew hair you could sit on.