[Howlin]

You know, from my vantage point in front of the TV that day, the tops of the towers appeared to be completely engulfed in smoke most of the time. I don't think a helicopter could have landed.

[Howlin]

Looking at the picture above, I'd agree.

[Andrew Byler]

You need a picture from above, not from below. Tower 1 had a smoke free area on the roof.

[Jordo]

If you look at other pictures, it seems that the roof of the North Tower was partly cleared of smoke by the breeze from the west.

I can't find a view from the north at the moment (which I seem to recall showed this best), but look at page 36 of the October issue of America's 1st Freedom (the NRA magazine) if you have access to it. This picture is from the east-northeast, fairly near the towers. The north face of the North Tower is partly clear of smoke all the way to the roof. The top of the antenna tower is also clear. This photo was taken just moments after the plane hit the South Tower; probably the fire in the North Tower was still spreading, and the smoke got worse later.

The smoke from the North Tower seems to have completely covered the roof of the South Tower, pretty much the whole time.

I wonder if the antenna on the North Tower also interfered with possible helicopter landings?