This is by far the most frustrating glitch I've encountered in Skyrim. I've died about 10 times from fall damage when Meridia carried me into the sky both when returning the beacon and completing the quest. It is just as frustrating since Im on 360 and there isn't an unofficial patch to fix this bug.

I have fallen several times as well. All you can do is reload. Eventually, it should work out. It worked out for me after three reloads, for my son, about five. I save a lot, so only lost about 30 seconds.