Bloody-Disgusting has a full synopsis for the project:
"Lost in a mysterious cloudbank, a rookie pilot and her four teenage friends must contend with a freak mechanical failure that first sends their small plane climbing to an impossible height, and then plummeting through endless mist. After regaining control, the survivors are confronted with a horrifying realization - the very ground beneath them has vanished and a malevolent force lurking in the clouds wants them dead."
This early trailer looks great, although the visual FX work still hasn't been completed. Altitude is being directed by Kaare Andrews and stars Jessica Lowndes and Julianna Guill. No word on distribution yet, but I'm guessing someone will pick it up based on this trailer alone.
Skip past the break to check out the preview in its full Lovecraftian glory.