Once again: assume the airplane is moving at 60 miles an hour to the
north. The tread mill then by definition is turning so that the belt is
going 60 miles an hour to the south. The wheels are turning as though
the airplane was going 120 miles an hour on the runway. If 60 is enough
airspeed for this airplane to lift off, the pilot just needs to apply
back pressure to the yoke. It's a question nicely phrased to make some
of us draw the wrong inferences: that's how come this is the 197th
response, and I think it's correct but then again others who don't
agree think they are correct as well. They have a right to be wrong
:-)!