That is a pretty good idea and could be practiced once to see how well the helo pulls the attention of the zombies. It would probably do a good job to prevent zombie reinforcements. But, I am not sure how effective it would be to get the zombies inside
the hospital. Maybe there are only
smart ones there. But, you are asking normal zombies to detect the sound above them, see the sound maker a couple of blocks away and head downstairs. It might be a bit much for the average zombie. The behavior we have observed is they run to the sound. They do not have the cognitive ability to run to where the sound will be.
Depending on the location, Tonya could stay at
the tower with the Helo functioning as a repeater to improve range. I would use what was saved in lift capacity to have a 55gallon Drum of Fun for our friends the zombies. But, the first priority is the other chopper. Hospital supplies are a secondary objective.