Section 437.59 - Key flight-safety event limitations(a) A permittee must conduct any key flight-safety event so that the reusable suborbital vehicle's instantaneous impact point, including its expected dispersion, is over an unpopulated or sparsely populated area. At a minimum, a key flight-safety event includes:(1) Ignition of any primary rocket engine,(2) Any staging event, or(3) Any envelope expansion.(b) A permittee must conduct each reusable suborbital vehicle flight so that the reentry impact point does not loiter over a populated area.