Iron Wings

In the Pit, Gorgond, there are iron troop launcher vehicles scattered around the map that work as a cannon. For this achievement, find the cannon located at 46, 31. When inside the vehicle, you will see two rings directly in front of you, aim the cannon such that the trajectory line goes through the ring (shown on screenshot) on the right. You will land on the other side of the map close to another cannon at 46.7, 22.3. There are 3 mobs close to this cannon which can be ignored if you jump into the cannon quickly. Aim the cannon through the same ring and repeat till you get the achievement.

As of 6.2.2 if you have unlocked flying in Draenor, you can actually just fly your mount through the rings after being shot out of the cannon once which causes them to appear.

This is bugged, but there is a way to make it work.

Some friends and I were trying this again and again today and from tracking the achievement not a single run was counting, even when we were going right through the center of the ring.

What worked for us was holding down right click while flying through the air and rapidly turning your character back and forth. This seemed to make the server update where we were and every time we made it through a ring while doing this it counted. We all had our achievements shortly after trying this method.