ECON Speed & Cost Index - B777
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Joined: Mar 2003
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From: Germany
ECON Speed & Cost Index - B777
During my performance questionnaire i stumbled upon the following question:
During cruise aircraft weight decreases and thus optimum flight level increases. If however, due to ATC restrictions, a climb to the higher level is not possible, ECON Speed will be higher in the actual level than in the higher level. True or False?
My gut feeling is that the statement is correct, as with an increasing cost index optimum altitude will decrease, so if you cannot get the higher optimum level, you can increase your cost index to lower your optimum altitude to the actual level and thus, you would fly faster.
Coming from the CRJ Series the whole concept of ECON Speed and Cost Index is new to me and my explanation (if it is even correct...) sounds a bit weak... Especially as it really doesn't explain why flying faster should be more economical...
Could anybody shed a bit more light on this one? Thanks very much for taking the time
During cruise aircraft weight decreases and thus optimum flight level increases. If however, due to ATC restrictions, a climb to the higher level is not possible, ECON Speed will be higher in the actual level than in the higher level. True or False?
My gut feeling is that the statement is correct, as with an increasing cost index optimum altitude will decrease, so if you cannot get the higher optimum level, you can increase your cost index to lower your optimum altitude to the actual level and thus, you would fly faster.
Coming from the CRJ Series the whole concept of ECON Speed and Cost Index is new to me and my explanation (if it is even correct...) sounds a bit weak... Especially as it really doesn't explain why flying faster should be more economical...
Could anybody shed a bit more light on this one? Thanks very much for taking the time
