I'm not sure if this is alrdy posted.
You need to be a druid for this, have flying form and X-52 Rocket Helmet.
Go to a lake, use your flying form, fly as high as possible, when there, disform and use your Helmet.
You should be above this invisible wall, then put your flying form bk on asap.
You will be able to fly as high as you want
I'm Hunter, I found a Druid to test this for me, so I couldn't check everything. I'll try that later (When he had to go he disformed, it took 53 seconds before he saw the ground :P)