My guess is the simple explanation is that the fellas were too busy gazing out the window, while in severe CAVOK. And in that part of the world, who could blame them!
Find it hard to believe it happened IMC.
I don't disagree with you Wazza, it sounded like a classic case of 'star gazing' mixed perhaps with a degree of computer complacency.
However the issues highlighted from the 2005 ATSB survey on the GNSS approaches are still current as the machinery (Airbus and Boeing) hasn't had any giant technological leaps forward since then and the same can be said for the approach design principles...be interesting to have a similar survey conducted now and see what the results would be...but back to the thread, sorry for the drift Mods!
