What went wrong to allow 2 Planes to fly into the WTC and 1 into the Pentagon?

Doesn't NORAD have more advanced technology than that? Are we ancient, when it comes to scrambling our forces while under attack, couldn't our planes just fly out to take a look if something was fishy on 9/11, they didn't have to shoot them down right away? I'm just wondering if our Homeland Security is that Weak?