The NATS system was down for 36 minutes or so - for the rest of the minutes in the year everything was fine. The reason the recovery, which led to the misery, expense and frustration, took so long is largely due to the whole aviation sector in the London area at running at 98% (I'm not sure the BBC post about NATS running at 98% is strictly accurate) and it cannot cope with any interference. That interference may be a runway closure due to a BA returning with an engine cowl, a security scare in a terminal or a drop in temperature of a degree that wasn't forecast leading to snow instead of sleet or thick fog resulting in LVPs. It is unacceptable that NATS had a failure with such severe consequences, but as previous posters have pointed out nothing is infallible and the UK's continued dallying over airport expansion is one of the real culprits in this incident. The Government and the opposition have all been bumping their gums over this issue whilst they collectively dance round their handbags over aviation infrastructure improvements in the SE. And so it will continue........