You are raising an horrific and almost unimaginable endgame, but yes, obviously people in charge of security of the UK will certainly have specific plans and contingencies if the worst came to pass.

What those would be, I obviously don't know but yes, one option is clearly to shoot the plane down. If it had been hijacked then that is one decision that someobody would ultimately have to make and I don't need to list the pros and cons of it here as if you think about it, they are obvious. The circumstances where the choice would be to shoot it down would be "hardly any" but you have the choice if you have fighter jets deployed, and you don't have the choice if you don't.

We had this discussion on here ad infinitum re 9/11. I think a fair summary is that if they had known in advance that the planes would definitely hit the twin towers, and if shooting down the plane was possible over water or relatively empty countryside, then it may have been done. But sadly the hijackers didn't file a flight plan and so one horrible consequence of shooting the plane down (amongst a million) is that you would by definition never ever know or be able to prove that it was the lesser of evils. Instantly a hundred conspiracists would lodge proof that the plane was only going to be detoured and land safely, as some protest, and the nasty government cynically killed its own people when there was no need.

It's analogous to when some unfortunate child meets a nasty end and then there are a hundred criticisms and recommendations so that it "will never happen again". But what is normally overlooked is that had the social workers and other agencies done all those things, there would by definition never be any proof that they had "saved that child's life". And they would probably be roundly criticised by many for (eg) taking the child into care, etc. The main difference is that the criticism for shooting down a plane and killing deliberately hundreds of civilians would be the mother of all shiitstorms.

If a plane is over a populated area then I wouldn't envy the person ultimately having to make those decisions but as I say, it is reasonable to have the option, even if you might almost never imagine circumstances where you would actually use it.

They are there in an observation role - they'll take a look at the flight deck and make sure the pilots are in control and not harassed, especially if contact is lost, and generally look for anything unusual including possible damage. It also sends a clear message that any indication of a threat will taken seriously and treated extremely seriously.

It didn't fly over the city centre - very few do, they tend to approach along the Pennines and from the East over Hyde/Stockport, or from the West over Knutsford/Northwich depending on prevailing winds. QR23 approached from the direction of London and circled over the Pennines near Buxton while the Typhoon was scrambled, it then flew in over Stockport.

And yes, if it became clear the aircraft had been hijacked and was absolutely, definitely, 100% about to be used as a flying bomb it could potentially be shot down. Though reaching that decision would be a nightmare.

Yeah I knew about the Vulcan bombing run after reading the book about it a few years ago. A typically British operation with good dollops of cock-up alongside ingenuity, bravery and determination.
I also knew some US B-2's had done some bombing runs from America to targets in the Middle East and back again recently but wasn't sure if any fighters had done. (I know the Tornado is used as a bomber these days).
Just got to say, I fecking adore the B-2 (in engineering/aircraft context). Awesome aircraft.

yes think it was a qatar to manchester flight.

he has been sectioned under the mental health act

it would be down to david cameron to make the decision whether to shoot a plane down or not i read today

I'm not sure about Camoron, but if it was Tony Bliar, he'd ask "God", and then do what he convinced himself the imaginary voice in his head wanted. That is how mad things are.

An impossible decision to make in the UK, a little easier in the USA, so for instance when Payne Stewarts private jet decompressed and killed everyone on board but kept flying for hours the military followed it down to the ground (almost) when it finally ran out of fuel and crashed in an unpopulated area, there is speculation that they would have shot it down were it to be heading for a city.

Slightly different scenario in the UK with a large aircraft thats going to make a big mess on the ground whether it falls naturally or you blow it up in mid air, there aren't too many places on the normal flight paths that you cold pick to say "Heres a good place to explode a large passenger jet over with a guarantee that no-one lives beneath".

Odsal? big crater there already

That's so crass, I'm actually lost for words.

I've never seen that one before.