The observer in the jump seat was a licensed pilot with AB type ratings but was leaving the conduct of the flight test to the guy in charge (who unfortunately got fixated); so, did not pull the throttles until he saw the wall coming up [and self preservation instincts took over].
Of course there are now new procedures:
- High power runs on two (not four) opposite engines at a time
- Chocks always to be used -- people stopped using them because they tend to get jammed and the a/c has to be subsequently pushed back to retrieve the chocks.