Originally Posted by
filejw
Ref Airbubbba comment on KIX ILS 24L and FedEx. I most likely caused by hitting app arm to early. The arrival transition calls for LNAV/VNAV in most a/c and if you select APP to early the aircraft will start looking for LOC/GS . Iv seen this happen in more than one type over the years.
That would be my suspicion as well. And maybe they went back out of approach mode when it started to chase, hurriedly tried to reselect things in the box and dropped some constraints.
On the vertical profile you have that mandatory 2600 ft. crossing just as you start the turn to intercept final. I've shot that approach with and without GPS over the years and sometimes the plane does the intercept gracefully but other times it starts to hunt as you turn toward KN. If it doesn't settle down you need to reduce the automation and, in the worst case, fly the plane.
Perhaps the incident I saw had the ILS extended off the FAF and inadvertently deleted the (at or above) 2000 ft. and 1600 ft. altitude constraints. Maybe they went to 1200 ft. way too soon, caught the mistake and climbed back up on profile.
Originally Posted by
Basil
So, if pilots can work that out, why don't our flight ops departments insist that positive action has to be taken to delete an altitude restriction otherwise it remains in place even when cleaning up?
Otherwise the tool (FMS) is damaging the workpiece (V-Nav).
That's one of the reasons I was hoping we would soon find out more about the A380 incident at MEL.
They were 15 miles from the runway. Looks like a 3000 ft. crossing restriction at SUDOS and 2000 ft. at ML627. If they were still on vectors maybe a misread of the altitude clearance, serious at any altitude but potentially deadly down low.
Or, were they given direct to SUDOS and cleared for the approach and somehow started down early on some faulty vertical guidance? Did they sequence the waypoints to go to ML627 and thought they could descend to 2000 ft.?
Maybe we will know in a year or so.
In this golden era of the FMS there seem to be subtle traps on waypoints and constraints that differ on each aircraft I've flown. On some planes if you get a vector to final you need to do an intercept to a waypoint ahead or it will not become 'active'. On others it doesn't matter and you can concentrate on flying the approach.
I've certainly armed approach mode too soon. And too late. And this RNP stuff is all automatic until it messes up.
Originally Posted by
Derfred
Does anyone have any idea what he is talking about?
My apologies, I let myself lapse into pilot jargon and perhaps used some terms unfamiliar to you. I wasn't familiar with a Flight Notification and certainly have learned from this discussion myself.
