Diffuse subarachnoid hemorrhage is commonly attributed to the rupture of intracranial aneurysms or other vascular malformations. Non-aneurysmal hemorrhages often have a characteristic pattern or clear mechanism (e.g. trauma) with an often more benign clinical course. We report the case of a diffuse non-aneurysmal subarachnoid hemorrhage due to sudden gravitational changes encountered during complex airflight maneuvers, complicated by hydrocephalus and cerebral vasospasm. This case illustrates a rare phenomenon that may again be encountered in the future with the advent and advancement of civilian spaceflight.