System attack or just stupid terrorists?
The “foiled” terrorist attack looks suspiciously like an attack on the underlying system, rather than an actual attempt to blow planes up - it’s almost laughable that terrorists in this day and age could hope to get explosive devices onto planes in hand luggage.
If we decide that the terrorists aren’t stupid, the attack begins to look decidedly different. They’ve succeeded in causing absolute chaos in one of the busiest weekends in the british airline calendar, the effects of which will probably drag on for a few days. If you wanted to be really nasty, they’ve also caused a large number of people to be trapped in one place, and extremely vulnerable to attack. The BBC report says Heathrow Terminal 1 is “jam packed”.
I suspect that a terrorist organisation will look at something like this as relatively cheap, too - 18 peons arrested, sure, but we know they can afford the manpower and they’ve once again demonstrated that the air travel infrastructure our society is so reliant on is extremely fragile and vulnerable.