Slightly off-topic, but the Cathay/NW incident described above reminds of a story from the early days of the jet age. Apparently, a BOAC Comet IV was cruising at a FL somewhat higher than a (faster) PAA 707.
A rather snooty English voice enquired of the PAA 707: "what are you doing DOWN there?"
Quick as a flash, the American pilot responded "mach 0.83, buddy!"