I feel safer already having the fucking psychiatrist running the ship. Nothng screams "EMERGENCY PROCEDURE QUALIFICATIONS" like a career spent dealing with klingon gender identity issues.
When I was a therapist, the character of Troi gave me hope of a future where we would be accepted and appreciated and deemed to be totally useless but still get all the great Starfleet perks.
Well, I'm not going to look it up, but I think this isn't so much a ship function as much as a last ditch "use a bomb to blow off the part of the ship that will explode in a crash" kind of thing.
I like how it gently glides to a landing at the end.
It was mentioned offhand in ST:TOS and the thought of it became such a part of obsessive Trekkie lore that they did an emergency saucer separation it in the first episode of TNG as fanservice. So fans complained, because the situation didn't really call for it.