Some questions:
1) When the engine fails, would the pilot drop the nose to gain speed and maintain lift?
2) would the stall alert sound at the time?
3) what other alarms would be going off in the cabin? Could those alarms be turned off?
4)Just before impact, would the pilot raise the noise of the plane to keep the front landing gear from impacting the water first?
5) would the stall warning go off at that point (10-20 feet above the surface?
6) in this video beginning at 0:16;
https://www.youtube.com/watch?v=PnLUVosInNQ
There are no alarms or alerts in the plane for the first 10 seconds, then the stall warning is heard (0:27) and the plane impacts the surface (0:37). Is that inconsistent with the sounds one would expect to hear from the warning systems on the plane?
Yes, the stall warning horn coming on half the wingspan of the plane above the surface is a reasonable rule of thumb. Ten seconds of horn tells me the pilot was not hasty or clumsy, so long as it’s still going as the aircraft touches down.
HF
In answer to your questions, it all depends upon the options available in the instrument group used in that particular aircraft. You would need to talk to a pilot of that particular aircraft and/or consult the pilot’s handbook for the Cessna 208B. A stall warning is a typical safety feature these days, particularly for a commercial aircraft.
Suffice it to say that confusing Puente’s comment about the alarm that went off when the engine quit with any other alarms that went off later, such as the alarm just before splashdown, is really unreasonable to the nth degree. There really is no good excuse for it. Even your typical automobile has a number of warning alarms these days, so jumping to a wild conclusion like that about a commercial aircraft is testing the limits of nonsense.