A resultant accident would also require: ATC to ignore the false transmission and take no action. The departing pilots to accept a new voice and a clearly inf

A resultant accident would also require: ATC to ignore the false transmission and take no action. The departing pilots to accept a new voice and a clearly inferior/weak radio clearance as fact without verifying. The departing pilots to not have situational awareness of an aircraft previously cleared to land on their runway. The departing pilots to still not check final approach on the just-falsely-cleared runway before taxiing into position. The landing pilots to have ignored the false transmission (also from a weak/inferior radio and new voice) clearing an aircraft onto their intended runway. The landing pilots to not be watching the runway when they break out at minimums. (assuming your foggy day is a worst-case scenario) The departing aircraft to have already started a takeoff roll and be more than 1,000' down the runway. (aircraft "touchdown zone" is not at the beginning of the runway) Possible? Yes. Not in my top ten fears as a pilot. Much of ATC is a collaboration between professionals, not a dictatorship. It's really an amazing thing to participate in.