Could helicopters have landed on the roof of the World Trade Center on Sep 11

I just saw the show Prime Time Live. They interviewed the 2 pilots, who flew to the World Trade Center, right after the planes hit the World Trade Center. The question they asked them? Could they have landed there helicopter on the roof and saved people. The South Tower, which the 2nd tower hit, would have been virtually impossible to land on. The entire roof was covered with smoke, plus the smoke was 200 feet high. But the North tower, that was the tower with the antenna. I think this roof was definitely landable. There was a corner area, the helicopter could have landed on. From what these police helicopter pilots said, they agreed there was a corner area, they could have landed on, but it was risky. It just seemed to me, these pilots didn't want to take any chances. What do people think. If you knew how to fly a helicopter and you were at the World Trade Center on Sep 11th, would you have tried to land on the North Tower. The North Tower was the tower with the Cantor Fitzgerald people. I dont think it was possible to land on the South Tower. I just read this Wall Street Journal article, on Could Helicopters have landed on the roof. You got to read the full article. They mentioned the the roof doors were locked and the people on the upper floors couldn't open the roof lock. But what was not mentioned in the Wall Street Journal article, which i found out, watching the show on Prime Time Live. The 2 pilots who were flying the helicopter, were in contact with the Port Authority on the ground. They spoke by cell phone. The Port Authority people the pilots were talking to, had the roof keys. All the pilots in the helicopter had to do, was land the helicopter on the ground and get the keys from the Port Authority people, then fly to the roof and open the roof door. Here's the link to the Wall Street Journal article. http://interactive.wsj.com/fr/emailthis/retrieve.cgi?id=SB1003784754436648720.djm