Kes wrote:To Mr Sacko. Apart from 9/11, can you provide ANY instances of exactly the same set of factors causing two aircraft accidents on the same day?

Even the incident in Tenerife, where one 747 taking off, hit another crossing the runway, it was a completely different set of factors that put the two aircraft in one place at the same time.

As regards the percentages argument, the fact that something happens or doesn't happen on one particular day, doesn't really affect the chances of it happening on another day. Unless you are talking about terrorist events, where security alerts ramp up after a terrorist event, and so you often find that the terrorists will not try anything while the authorities are on a higher alert status.

It’s not really an argument, it’s just maths.

If the chances of something happening on any given occasion are fixed, then the chances of it not happening in x number of occasions decrease as x increases.

Any coin toss has a 50/50 chance of heads. And every time I toss that coin it’s always 50/50.

The chance of it taking one toss to get a heads is 50%. The chance of it taking 2 is 25%. The chance of it taking 3 is 12.5%. Of 4, is 6.25%.

Another way of looking at ir Is to flip it around. What’s more likely - going 100 days without an accident or going 50? Or 1? Or 1,000,000? The larger the number, the less likely. The smaller, the more likely. The most likely number of days between crash days is 1.