According to one on-line terminal velocity calculator, an 80 kg mass with a cross-sectional area of 81 m² (9 meters x 9 meters) and with a drag coefficient of 1 (which is what a person has, a smooth ball has 0.1 or would need ten times (10x) more area, although the relationship between area and terminal velocity isn't linear with the Coefficient of Drag) would have a terminal velocity of 8 mph.
Since I've survived several bike crashes with nothing more that some (fairly serious) abrasions at similar velocities, that's about the fastest I'd want to hit a random point on the ground.
Here's the problem with that: (9 x 9) is a huge area. We're basically talking about a parachute (opening after escape). I can see some inflatable suit which could protect from penetration injuries, but I can't imagine anyone willingly wearing such a awful thing for extended periods, nor can I imagine that in an emergency, anyone would have time to put something like that on.
You should consider the (blatantly obvious, to anyone over 40) idea that if something better than a parachute was feasible, we'd be using it. Seems to me kevlar body panels, and a helmet would be about optimum. The elephant in the room is that if they have time to evacuate, you have to explain (credibly) why they don't have time to crash land.
