N121JM was a case of the Swiss Cheese model.
-Gulfstream designed a gust lock that did not work
-The FAA approved it.
-The pilots used no check list and missed that the gust lock was on - and these were experienced pilots.
-The kicker was the owners were paying for a SMS service to monitor the operation which was Part 91.
From the NTSB
"A review of data from the airplane’s quick access recorder revealed that the pilots had neglected to perform complete flight control checks before 98% of their previous 175 takeoffs in the airplane, indicating that this oversight was habitual and not an anomaly."
So there was bucket load on information available that said the pilots had "normalized their deviance" but no one picked it up.
The owner of the plane was on board. He did not get what he paid for.