Originally Posted by Sunvox

I spoke personally with the head of our combined fleet, and it is my clear understanding that this procedure was in place from day one one on the 767 fleet on one side of the merger. The LCA who performed my OE (who is the head LCA for the fleet) also explained how the use of Cost Index was arrived at from the beginning and he claims the appropriate international authorities approved the procedure long before the merger, but I have asked for written proof of this approval and have seen none.

Whether or not pilots have been following this procedure over the years I can not say. I can say that the captains from one side with whom I am flying today are in fact using cost index to set the speed when crossing the Atlantic and they are accepting variations up to and including .005 mach and saying that it is allowed. The difference is trivial I agree, but as a matter of simple principle it is wrong and so easily corrected as to be a complete mystery to me why anyone would be defending this procedure. Conversely I NEVER once flew with a captain on "the other side" that EVER used cost index to set the aircraft speed while crossing the Atlantic either before or after this procedure was introduced and I have been in this fleet since 1998. So in short I'm afraid the information I have to date says that your comment is wrong. I have been mistaken before so perhaps I will be proven wrong here again.


More to the point the discussion as to where the procedure came from is superfluous and I am sorry that my opening remarks even brought it up. The reasons and logic against this procedure are numerous, and the support in favor is dubious at best.

1) How much gas is saved flying .800 while in ECON versus .800 while the FMC is hard coded? I find any difference to be almost unbelievable.

2) IF (and it would be a big IF) If the FMC is better at calculating a "RECOMMENDED" altitude, as is suggested by the fleet technical specialists, how often would this differ from the hard coded "RECOMMENDED" altitude and how often would pilots actually be able to change altitude?

3) If flying Cost Index is so great why don't we adjust speeds around the terminal with cost index when ATC assigns 210, 180, or 160 and if flying those ATC assigned speeds is not a problem why is it so hard just to fly the speed assigned by ATC when you're over the Atlantic.

4) If Cost Index is picking the most efficient point on a curve and looking 400 miles out doesn't the whole efficiency get negated every time you change the Cost Index in your attempt to maintain a Constant Mach. In other words if you start out with a Cost Index of 50 and end up changing to a Cost Index of 60 wouldn't that have changed the recommendations from the very beginning.


In short the problems with this procedure are numerous and the benefits are non-existant or tiny at best so why on Earth would anyone defend trying to maintain a constant mach on the NAT Tracks by continuously manipulating Cost Index when the alternative is "set it and forget it" hard coding!