I have jumped from an airplane and it is like this. You throw yourself into a wide open space. Your arms flail as do your legs because they need to feel that there is an anchor, a reference point but there is nothing there. It is a sense of freedom which makes you want to scream with joy. It is a sense of terror which makes it hard to breath because your heart feels like it will beat out of your chest. You are lost and what you knew is gone. You do not know what will come next. But this entire feeling you have, this closeness with death, this discarding of everything you knew also makes you feel terribly, heart-breakingly alive.
We have all had these moments when we fall suddenly or trip or are hit with something unexpected. The moment, brief as it is sometimes lasting only seconds, seems to stretch itself out as our sense of it, our attention focuses on this event as it rarely focuses on anything. So small is the time, so precise is this attention, that you can count the moments from when a command issues forth in your brain and it finally reaches your hands (emanating like a slow wave upon an ocean) that stretch out to break your fall or fend off the danger or remove themselves from resting on the burning stove. This is also to be attentive, to be in the moment, to be alive.