Surviving a water landing from an ejector seat takes a fair bit of training.  IMO, a backup parachute system would probably be about as safe and cheaper. <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Ballistic_Recovery_Systems" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Ballistic_Recovery_Systems</a><p>Granted, scaling up from a <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Diamond_D-Jet" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Diamond_D-Jet</a> to a 787 would be extremely difficult.