atan((11700-7680+55)/(5.7*6076))=6.71 degrees.
atan((11700-7680+55)/((3.15+2.65)*6080))=6.59 degrees.
The published 6.59 degrees probably eliminates cumulative rounding errors.
So, with the 3.5 degree VGSI also at a TCH of 55 feet, it seems to me you'd be seeing a lot of white lights all the way from DOYPE to the threshold unless you push over into a far steeper descent angle somewhere in between.
Using the same logic, in order to intercept the VGSI 55 feet over the threshold, you would need descent angles of 7.59, 8.23, and 8.94 from the MAP (CEYAG) for Categories A, B, and C, respectively.
In fact, assuming the TDZ is 1000 feet down the runway and TDZE is 20 feet higher than the threshold, from CEYAG it's a 7.26 degree descent angle to the TDZ for Category A.
atan((9840-(7680+20))/((2.6*6076)+1000))=7.26 degrees.
Speculation Alert: Perhaps they maintained MDA all the all the way to CEYAG and then attempted VGSI intercept before reaching the threshold, resulting in excessive speed and a very steep descent angle.
Last edited by thcrozier; 8th Jan 2014 at 19:56.