Even in one of the most helicopter-savvy countries in the world it was not feasible to rescue anyone from either of the two towers (more than two, actually) of the WTC on 9/1/01.
With Piper Alpha the prime planned evacuation method was by helicopter from the helideck, but there too it was quite impractical to use helicopters despite having several well equipped rescue helicopters onsite with some of the best winching crews in the world.
Sadly, helicopters aren't the answer in this case.