MRC speed vs Cost Index
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CI = time costs per hr/fuel cost per lb. With CI 0 it is that other incidental costs are irrelivent, only fuel cost is relivent. Hence my question, in effect is CI 0 giving MRC in still air?
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Boeing FCTM: “Entry of zero for cost index results in maximumrange cruise.”
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You are correct LRC is MRC -1%. The trade between the increased speed and the reduced range is considered acceptable.
LRC was created by Boeing back before FMC's, ECON speeds & cost index computer data analysis. It provided an average compromise between fuel consumption & hourly operating cost that was very good for it's time. Speed wise I think it was Mmr Mach plus 5%.
Last edited by Private jet; 30th May 2023 at 06:13.