I'm guessing that any leak is likely to be small, and thus slow. And depending on how many vehicles are 'in flight' at once, and how easy it is to detect, they

I'm guessing that any leak is likely to be small, and thus slow. And depending on how many vehicles are 'in flight' at once, and how easy it is to detect, they could be slowed down before hitting atmospheric pressure to avoid shocks or vehicle damage.