The ground has a Pk of about 99.999%, not 100%; e.g.
21st March 1984
RAF Hawk T.1 XX251 CFS
Red Arrows
RAF Akrotiri Cyprus Hit the ground during display practice at Akrotiri, Cyprus
The impact forced the ejection seat through the canopy and deployed the chute dragging the pilot out
Flight Lieutenant Chris Hurst Inadvertent ejection
"You lucky, lucky, bastard!"