The Sauber reserve lost control of his car at Copse, bringing the session to an end 20 minutes earlier than planned due to barrier damage.
With his car's G-loading sensor switching on, van der Garde was taken to the circuit's medical centre, where he was later cleared of any injuries.
"I don't know what happened. First I had oversteer on the left side, then it went to the other side and I lost it," van der Garde, who had gone fourth fastest shortly before the accident, explained to GPUpdate.net.
Van der Garde said Sauber spent parts of the day running without FRIC ahead of the system's widespread ban, which could come into play at the German Grand Prix if teams do not unanimously agree to delay it until 2015.
"We changed the philosophy a bit because of the ban coming up," the Dutchman added.
"Sometimes [we used it], sometimes no. We have to see. If this happens we have to get prepared."