I would not use the viewing platform at LHR!!
The reason I say this is because I still can`t believe that BAA and H.M Govt are still using terrorism as an excuse for keeping it closed.
Lets look at the facts.
The viewing platform is isolated from the rest of the airport, so unless I`m James Bond and wish to absale down onto the lower roofs without being seen from inside Terminal 2 the only way a terrorist could attack a plane would be with a rocket/grenade launcher.
First problem. The only entrance is the small fire escape doors. To get to this I would have to either pass the entrance of terminal 2 and/or the bus station and Queens building. You usually have a group of BA pilots and stewardess waiting here plus an array of airport staff. So carrying rocket/grenade launcher would be quite noticeable.
Ok if I did manage to get onto the viewing platform it is very rare for NO ONE else to be there. Again I think a fellow spectator would notice a rocket/grenade launcher (unless he thought it was a new ultrazoom camera).
If the worst case scenario happened and I did fire a rocket/grenade launcher then I would have to make it across the roof,down the stairs before the police and/or special force are waiting for him at the door, and if after all this I did make it out the only exit from the airport grounds are through the tunnel and/or London Underground, and both of these would be closed off the very second an attack happened.
However I could just visit the viewing park in Manchester which is adjacent to the runway and launch an attack from there and speed away in an awaiting car and escape via the M56.
So lets hope that eventually BAA and H.M Govt see sense and re-open LHR viewing platform ASAP.
Remember by closing locations and by altering our everyday life we are letting the terrorists win !!!!.