Originally Posted by
easymxp
Hi!
I’m trying to find an easy rule of thumb to monitor my descent with significant tailwind on descent.
let’s assume tailwind is 50 knots at TOD, normally I use 3*altitude plus deceleration plus tailwind. For tailwind I use 1nm each 10knots of tailwind. I see this works with a high speed descent (say over 300 knots) but with our CI we have around 270 and it is not enough. Anyone with a better estimation of wind effects on descent computation?
If asking why I do all this when I have managed des , is bcs with trombone style arrivals (snake) most of the times I get major shortcut so to mitigate this I use OP des and stay lower
I find that the bus generally does a pretty good job with the profile. But... garbage in ==> garbage out. A "Trick" that I sometimes use during the descent preparation is to copy the active Flight plan into the secondary flight plan. Now I modify the secondary flight plan, into what I think we would REALLY get, in terms of ATC clearance. If you expect to fly from position X directly to the final fix, I would modify it (in the secondary) into that. If you now look back through the secondary flight plan you can take another point (before point X) and look at the predicted altitude/speed. You can make THAT altitude/speed combination a restriction in the PRIMARY flight plan. This way the 'bus will calculate an idle descent to that first restriction. You now have an accurate TOD... Hope this helps.
With regards to a rule of thumb 10 kts of tailwind adds about 1 nm... Obviously if you fly slower, you will spend MORE time in the tailwind condition, but the wind usually decreases with altitude...