Emergency landing on water is "standard procedure". You might have the impression that it's something which was creatively invented by the pilot at a moments notice, but it's really not. The engineers designed the airplane with the capability, included advice and checklist in the operation manual, they even put a button labeled "ditch" on the dash! Can't really see why they could not make such an autopilot program.
You completely misunderstand. I wasn't talking about a generic "emergency landing on water".
A plane suddenly loses power in a highly urbanized area. It's very near multiple airports. Prior to 2009, I have no expectation that an autopilot would have been equipped to judge whether it should attempt to land in a heavily-trafficked river. (I further have no expectation that it would have been equipped to notice in the highly plausible scenario of one or more small boats being in the way.)
It's not a question of landing on water, it's a question of making the decision to do so and where.
Humans have the judgement gained by a lifetime of learning. Computers only have what it occurs to us to put into them while we're sitting safe and sound in our little offices pushing little buttons that don't threaten our lives.
