I know someone who was at sea when their GPS stopped working. They found out later a nuclear sub had come into port around the same time. Seems like it wasn't a coincidence as gps outages are rare.
I remember hearing about the 1990 BOC single handed Round The World Race - where the competitors all noticed the CEP on their GPSes dropping way down, indicating SA had been switched off - and being amongst the first civilians to have noticed the Gulf War had started...
Where was this?
He could tell you, but his GPS was down.
Moreton bay, look it up. Few years ago now, but the sub visit was big news.