The problem shouldn't be with IE7, I think it is more likely the airspace.aero domain.
We have been making slight changes to the domain through the week, to make sure everyone can access the site.
Most ISPs should pick up the changes within 5 minutes or so, but sometimes it can take longer.
If you find that you can use the link from the left hand side of flightglobal.com (or the direct address http://www.flightglobal.com/AirSpace ) but not www.airspace.aero could you let us know which ISP you use, so we can try and get that sorted out?
And if you can't access it from flight global at all theres definitely something wrong somewhere!
Hope this helps,