For example the DJI Inspire is a drone with an inbuilt camera which flies at 50 mph. It can be bought for £2500 at Maplins – the high street electrical outlet. It is remote controlled and very robust. I'm not sure what the maximum altitude is at which it can fly, but there are plenty of drone forums which can give you advice on this. After three minutes of looking, I found a forum which says that the main height restrictions on drones is that they have internal restraints – ie they are programmed not to go beyond a certain height. However the forums say that it is relatively easy to adjust the drones, to bypass these restraints. The forums suggest that many drones will easily go up to 3000ft, at which point an accident with an aircraft is a real possibility.
So how could they be used by terrorists? Firstly they could be flown, preferably at night, onto the flight paths of major airports. Sucked into the engines, they could at the very least cause an emergency landing, at worst a major catastrophe. And there is nothing to stop anyone replacing the camera with plastic explosives, to add to the fun. And you could probably bring down a police helicopter Or you could fly one over a military installation and detonate explosives.
Once you've done that, the fun will really begin. After all, you won't even need to arm the drones. You will simply have to fly one in the vicinity of Heathrow and the army will have to shoot it down. This is a very expensive process – resulting in lots of bits of ordinance flying around and coming to earth in populated areas.
Presumably the army will start to use electronic countermeasures, but the terrorists will have to keep one step ahead to prevent the army jamming their signals.
Now I have to make a confession. I like to think of myself as a very clever chap, but I am not a military genius. If I have thought of this scheme, it's a fair bet that lots of terrorists will have realised the potential. And it's only a matter of time before they put drones to use.
So maybe the government should act now. Instead of snooping on our phones and internet and having pointless meetings of COBRA, perhaps they should just come up with some sensible regulations to restrict the use of drones. After all, these things compromise our privacy and now they are compromising our safety. It's probably best to introduce some proper regulation.
see also - Defense Vetting - how it fails to protect us