Only one G/A in thirty years of flying.
A couple of years ago on Malaysia Airlines from KUL to LHR. Was almost on the ground, or so it seemed, there was a massive surge of power and up we went at a rate that was hard to imagine. Quite a few screams and gripping of seat arms. After a couple of seconds I realised what was happening and was quite relaxed about it .
I never felt in any danger and was greatly impressed by the actions of the guys up front and the way the 747 could climb with very little fuel onboard.