Interesting about the jet age.
Aeroplane designs come and go, and yet the two original attempts at jet engine airline transportation still soldier on...the Comet (looking rather strange now in Nimrod disguise), and the Boeing 707, still earning its keep for a few operators (even a few of these stage III).
Concorde, a flash in the pan, which never made a cent (using proper accounting methods, not pie-in-the sky nonsense)for any airline operating it.