Going Down?

Update: Found a simple spot in Dalaran to complete this achievement. You will need a flying mount or a friend with a flying passenger mount (like the X-53 Rocket).

Attention: When your are thrown off a passenger vehicle you automatically obtain a parachute. You will receive the parachute even if you were already touching the ground, meaning your next jump or fall will activate it. Simply remove the buff before you take this leap of faith.

The jump location is located on a tower attached to The Silver Enclave (that's the Alliance "side" of Dalaran) directly above the treant fruit vendor Applebough, NOT the window with the plants but directly above that.

Simply JUMP off the ledge towards the street. Avoid jumping to your right (if you're looking outwards) as you might hit the lamp by the mailbox.
Walking off the ledge is not sufficient, you have to JUMP off.

Check out the image below if you have any trouble finding it or where you should JUMP towards.
Click here to view the location (imageshack).

Old Location in Shattrath:

This was my first post on this achievement so I will leave it here. Others have posted that jumping off of the Scryer's elevator (when it arrives at the top) will also grant this achievement. Here was my location, also located on the Scryer's tier.
Fall close to the right side, the tarp is slanted and its just about 64 yards in the center and 65 on the slanted side.
http://img124.imageshack.us/img124/3975/goingdown2to4.jpg

After a bit of searching, I found the perfect spot for completing this achievement.

Scryer's Teir. Mount up at the top. Once the elevator comes to the top, run and jump off the edge of the elevator platform at an angle so that you fall below the pathway immediately below, maximizing your fall distance.

If you have full hp before the leap, you should end with less than 1% of your health and 10 achievement points higher.

It doesn't count if you land in water. (Tested in beta)