In the early days of jet transport flying, pilots who had come from piston transports tended to slow w a y down when turbulence was encountered, and if this was at or near the aerodynamic ceiling for the weight, often found the classic jet upset was in the cards.
This was....very bad news.
Unfortunately, the older jets had rather poor data on the proper speeds to be flown in turbulence, so this certainly didn't help.
The L1011 for example has very good data on the subject, provided of course that the pilots actually READ it in the AFM...some of course apparently know better
I even had one pilot long ago mention that the L1011 wing was unsuitable for any flight above FL350 saying....'it's just like the Constellation, a bad performer up high.'
I asked him if he had actually referred to the performance data and the answer was....'why bother, it's all a bunch of nonsense anyway.'
Some never learn
L1011 Turbulence speeds... M.82-.84 or if above 290KIAS, slow to that speed regardless of mach number.
This is for the standard body aeroplane, short body similar.
Get the TriStar too slow, expect big problems as the aeroplane is designed as a high speed cruiser.
Cruise all day long at M.86 (standard body aeroplane), passing most anything else like they were dragging a boat anchor.
