BCP and Car Crashes
A friend once explained to me the need for a business continuity plan like this.
You probably have a pretty good idea of what you need to do if you are in a serious car accident. You know you should make sure everybody is safe. You know you should call the emergency services. You know you should collect license plates and contact details of any witnesses, call your insurer, and so on.
But when you get a whack on your head from an airbag exploding, you're no longer thinking clearly. You start to do what's obvious, not what's important. Your priorities will be wrong, and things will get missed.
A disaster is just like that.
Which is why you need to think out your plan in advance and write it down. The things you need to do in that plan may seem obvious, but chances are you will forget to do some of them if you do not have that list in front of you.
I've found, from bitter experience, that this analogy is accurate.
[Shameless plug: if you haven't got a plan which is written down and readily accessible, check out Plan424]