LOLSo according to this logic it's safest to just stay at the beginning of a runway, as high as possible, with as much fuel in the tanks as possible :). just kidding :) Terops. here's mathematical proof of Girls being evil :)First, girls use your time AND money, so let's assume thatGirls = time * money, now remembering that time=money, we getGirls = money^2Also, recalling that money is the root of all evil we haveGirls = (sqrt(evil))^2 = evil. :-bat

"Why would the takeoff speeds be deleted unless the position shift entry has some effect on the takeoff speed calculations?"Interesting... Sounds like this is FMC specific (i.e. optional on some FMC's).It does, of course, sound logical that the FMC would delete the speeds for safety reasons. Does your AOM say it can automatically recompute the V speeds after an entry (or does it just delete the old ones?). Note that there are a lot of variations. Some FMC's are not programmed to compute all the V speeds. You may need to make a manual entry (Our 747-400's don't compute V1 for example and don't have a RWY COND (WET/DRY) selection).Thanks.Cheers.Ian.P.S. BTW, my theory is a little rusty. Which V speeds _don't_ rely on runway length?

>Does your AOM say it can automatically recompute the V speeds after an entry (or does it just delete the old ones?).It says:"Entry of a value after takeoff speeds are selected removes the speeds and displays the scratchpadmessage TAKEOFF SPEEDS DELETED."It seems that only FMCs that calculate V speeds automatically have the RWY/POS field. (It also seems that FMCs that calculate V speeds are the only ones where you can enter flap setting, runway wind, etc.)>P.S. BTW, my theory is a little rusty. Which V speeds _don't_>rely on runway length?This really is not my area of expertise (;-)), but V2 should be the same regardless of runway length as far as I know. I think it's the same case with Vr, but I'm not sure.Martin767 fetishistIt's a lot like life and that's what's appealing

Martin,You are right, Vr and V2 are "aerodynamic" speeds and vary with weight and configuration. V1 will depends on many variables but will never be more than Vr and never less than Vmcg.Kevin in CYOW

Thanks, guys!Cheers.Ian.