It was 1980 something and the neighbor across the street had just brought in a mound of mulch for his garden and had it on the side of the road. This is a neighborhood street btw. Naturally, my older brother, his friends and some neighbor kids start going up and over the mound, some even jumping a little bit.
Being the little brother who had to do what his older brother was doing better than him. Got on my BMX and rode straight at that thing as fast as I could. I started up that mound and caught some serious air. All I remember from that point was be and the bike while in the air start tilting back.
I then woke up several hours later in the ER. I had landed on my back on the road and hit the back of my head and knocked myself out.
My friends said it looked awesome till I started falling back. My brother still talks about that today and how it was probably the dumbest thing I did in my youth.
In answer to your question of how far the jump was, I have no idea, but I wish someone would have taken a picture or video of it.