I have to say, not much
. I still have this needing 0.9 degree CW
Sorry I can't host the image, but I will email it to you if you want to send me your email address.
The reference I am suggesting is to draw a line along the tops of the little approach lights just underneath the wheels of the aircraft. If those lights are horizontal - and if you had the whole of the runway in shot - then the runway surface itself would be horizontal. You can forget about the horizon in the distance, which is too bumpy. Also, Tim's cross bars are variable and simply not reliable enough.
Drop me an email if you need any further help.
[Edited 2006-01-07 14:56:08]