Didn't that China Airlines 747SP get close to, or exceed, Mach 1 during its upset, they just didn't have the DFDR data to prove it?
Yup... and it never flew straight thereafter ever again.
It pitched up in CYQT a few years ago, fleeing creditors apparently, as a huge Biz-Jet entitled
Global Peace Ambassadors, and sat on the apron for months. Then it disappeared suddenly and flew right across the US under VFR (honest!) to somewhere in Mexico for overhaul.
Interesting.