Have you had a I am going to die in a second experience?

The feeling of real fear that your time was up?

I had.
After the London bombings in 2005, when security measures increased, we were advised to watch for abandoned backpacks and the likes in train stations, and other soft spots.
I went back to my hometown by train, after a visit to my brother, in the middle of the night, when a guy who was sitting some places away from me, went to the toilet (I assumed) and left his bag unattended.
I was sure that he was a terrorist and the bag contained a bomb (they really got to me, the Dutch security services :-) ).
My last seconds on Earth, I was convinced (I said my goodbyes to my loved ones in my head)....
The fear of dying was so true, so real, that I was paralyzed and didn’t do shit to avoid it.
It was a sad moment.

You had similar fears?

The ‘bomb’ didn’t go off and I was fine!