difference in wind speed/direction required to make putting a/c a dangerous proposition would be immense and unheard of within close band levels
You need to get out more. We are working here right now in the Gulf with wind speed changes of 100kts or more over a 3000' interval. In other places I have worked where jetstreams are prevalent, you can get 120kt wind speed changes within 2000' feet or less.
You talk about people not being able to do the calculations to work out how much wind would be required to move the aircraft in question; so what???
The point I am making is that is that it is too complicated to work out for each situation, yet to use the technique to provide
assurance , surely you would have to work it out? It's the people making the argument for using headings who need to know. That's why. You can't sit there and argue for the use of a technique if you can't even assess it's risk.
the difference in wind being experienced by two a/c in such proximity needed to create such a phenomenon would be akin to divine intervention
Obviously the big guy is in action every day- you are just too ignorant to realise it.
Now as a very basic example, lets work thru one (just so you get the idea.
). In the example used earlier in the thread, we have a square a b
---------------------c ------ d
Aircraft 1 is tracking c to d, a B738 FL230, and a/c 2 is tracking b to c, an A345 climbing from FL200 to FL380and will pass each other at the roughly the midpoint by roughly 7-8 nm.
Assuming the controller is comfortable with this margin he locks the headings. The wind at FL200 is 300/30, the wind at FL230 is 300/120, and at FL380 is 300/140. As the wind speed increases as a/c2 climbs, the FMS would normally adjust heading to the right to make good the track from b to c. But with the heading locked, a/c 2 begins to drift left, at potentially 90kts, as he climbs into the stronger wind. As a/c 2 is an A340, so may take up to 3 hours to climb over the 738
, the drift could be enormous (and in the example may take as little as 2 minutes to lose sep, depending on the wind gradient). Even worse, this drift will not be immediately apparent. Only if you keep monitoring the situation will it become so.
You think this sort of wind would be divine? Well, in the Gulf we work with this sort of wind for about 3 months of the year (now).
Just trying to get people to think about something often considered 'gospel'
