- last reversal event took place over centuries with "Mag North" moving as much as 60 degrees in a 10 day period. Period defined as time of weak mag activity with mag "North/south" swapping on numerous occasions before settling down.
That will certainly keep the runway painting people busy as they already have been in Ireland, painting out and repainting the numbers. Actually, the old numbers tend to wear through again, giving a bit of a 'oops, wrong airport' fright on finals!