pitch pull

I found this.

Explaining his reasoning, Pyles cited what is called a "pitch-pull,"
when a sailor's weight is shifted incorrectly
or the fore of the boat digs into a wave,
causing the front of the boat to stop while the back
continues to move forward.
Pyles said that this often results in the sailor being thrust
through the air about 20 feet.

http://74.125.39.104/search?q=cache:djlst4GcvXEJ:thedaily.washington.edu/2001/3/28/come-sail-away-get-a-clue-about-the-u/+%22pitch+pull%22+sailing&hl=en&ct=clnk&cd=9&gl=uk

Hope it helps.

New2grammar

That's interesting. 

I agree.  In other sports, your conveyance would probably flip end for end.  But I can imagine a toboggan travelling rapidly downhill in deep snow, going over a "jump," and noseing into a drift, stopping abruptly, and "pitching" the riders ahead, past the conveyance and into the snow.  The "pitching" part of your expression is quite common.  A horse who doesn't like his rider may stop abruptly to pitch the rider over the horse's head and onto the ground.  Or, rapidly approaching an object to be jumped, he may abruptly change his mind and pitch the rider over the object.    - A.

While I was trying to find the term for you, I saw quite a few results connected with aviation, particularly helicopter flying. I have to admit that I had never heard the term before.