Years ago I generated data for B727-200 levels for best range for various head/tail winds and weights at M.80. At lower levels I used the recommended IAS. That was a huge job with interesting results and it was mainly used on Sydney - Perth runs. TAS and fuel flow changes related to different levels was the best way to adjust for wind gradients Thirty years ago the traffic was sparse enough to not need more complex calculations for speed changes at a fixed level.
Rules of thumb for wind gradients turned out to be a poor substitute for a lot of better preparation.
Last edited by autoflight; 22nd May 2013 at 00:10.
Reason: clarity