Wasn't WWOR transmitted off the antenna tower? I
know WGN in Chicago is done
from the antenna array on the Sears Tower and I'm fairly sure that WWOR had
something in conncetion to the WTC
I'm not a TV engineering guy and it's been a long time since my college
radio days but here's my less than educated guess.
Many of the NY stations must have had alternate locations (IIRC many at
their old the Empire State Building) in case of emergency and also
because of the problem of the signal from the tower being blocked in
some parts of the city.
IIRC Many of the VHF channels also broadcast their signal on a second
UHF channel shortly after the twin towers went up to get full coverage
in Manhattan before the antennas moved to the towers -- so I assume that
they had some kind of backup location or plan.
Channels and 5 (Fox -- used to be WNEW Metromedia),9 (WWOR), 11(WPIX)
went black for a while. It appears that the ABC, CBS and NBC affiliates
switched quickly over to a backup set of antennas.