Maui,
Whilst your thrust on avoiding the minutae is well intentioned, here it is clearly wrong.
There have been several aircraft that have experienced upsets in the cruise recently, partly - I believe - due to the fear of Mmo exceedence by the PF. Usually these events have been caused by a sudden decreasing tailwind (or increasing headwind). The fear of watching the trend arrow heading quickly north to the red led the pilot to disconnect the ATHR in a panic that (IMHO) he was about to be reported through the FOQA system. All hell broke loose thereafter but that's the subject for another thread.
Airbus have been stressing recently - including at its most recent safety conference - that transient excursions beyond Mmo are OK as there is a huge margin to .... you guessed it Md (or Vd).
Had the pilots known of Vd or Md, they would been aware that the wings are not going to fall off at Mmo +1kt and their rather embarrassing upsets never would have occurred.
As Vilas said, Airbus FBW aircraft have a gap of about 35kts/M0.07 from Vmo/Mmo to Vd/Md respectively. I imagine that Boeing would be fairly similar, although flight testing procedures for non FBW certification vary slightly for the Dive.
Last edited by compressor stall; 23rd May 2018 at 14:20.