It depends on how much he got out. Maybe it was enough to slow him down a little and the roof did the rest (not that that wouldn't hurt mind). I saw a double malfunction on video of Bridge Day and the guy had a streamer and landed in the river.
AFAIK it was a survivable event
I mean, who lands like that without a parachute and lives?
you'd be surprised, there was the Lancaster rear gunner Nicholas Alkemade, and then there are the ones who do it on purpose like the guy with the two nets and the four cranes, and the guy in England with the helicopter and the cardboard boxes