[TinkersDam]

Right. Too much weight aft can cause just what happened. A sharp climb, full stall, a quick roll or two, even a roll to fully inverted.

Trouble is there is supposed to be a margin of error and there are supposed to be weight and balance calculations.

[MindBender26]

Exactly. There are supposed to be proceedures to prevent every calamity; Chernobyl, Challanger, Columbine, etc.

Proceedures don't FUBAR. People do.