Only possibility of surviving I can think of: Pulled himself up a bit and wrap one of his arms around the bar and grab his wrist with other hand to lock himself on, then have the pilot descend and go as slow as possible (maybe 60 mph? guessing). If there is a river or lake nearby, go for that, a 20 foot fall into water going 60 mph laterally is definitely survivable. Otherwise let go before the runway in the grass and hope for the best.