My dad went 48 years at United as an engineer at the MOB here in San Francisco.
He was on the team that bought the Caravelle, we lived in France for a while. That was a top gap intermediate route aircraft, and he first domestic jet in the US, when the Electra went sour.
They also evaluated but did not buy Concorde.
I flew employee passes on DC-3, DC-4, DC-6, DC-7, 8, and 10. Vickers Viscount which they gpt with the Capitol purchase. Wonderful aircraft.
He was at UAL in the Douglas days, but we saw 727, 737, 4,5,6 and 7. He managed the customer kit specifications for UA for the 777. A wonderful aircraft.
i'm amazed how safe that the industry has become. He did performance evaluation in some riskier times. UAL lost a 727 at Salt Lake Coty and dad spent a week with test pilots crashing on an imaginary hard deck over our Bay at 5000 feet.