Optimum Cruise Alt formula

[Trackdiamond]

Thanks for the informative replies guys.

Skyjob..many thanks but I was looking for Altitude reckoning at preflt planing stage..in cases of Computer flt plans not accessible and no previous experience on the route segment. I.e. you are going to a new destinantion.What Altitude to plan for given the distance.Also assuming the Quick Planning FL,Fuel,Time graphs not available..just a simple rule of thumb mental excercise.It is understood that FMS can compute all this.Just wanted to reert to manual methods.Assume FMS has failed that day too!

Sorry about the duplicated post.Will maintain it on this Techlog Forum for more visibility.

Thanks