In the good olde days of the first jet travel some crews took their flights too high too soon and with the onset on unsettled conditions found themselves in an upset situation.
flying the aircraft too close to the stall buffet speeds either high speed stall then 'low 'speed buffet...The 'stall' speed closed up to the high speed index.
The lessons learn't was that one didn't take the flight too high too soon-despite weather ahead etc...
Several accidents were credited to this \'causal\' factor until the industry modified it\'s procedures and respected the buffets..
