FDX - 290 Into MEM/IND
10-05-2010, 05:45 PM
#12
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Originally Posted by MacGuy2
Follow-up on the follow-up.
Are any of the other FMS fleets (besides the 777) doing this CI jiggle to approximate the 290 kias descent?
MG2
Are any of the other FMS fleets (besides the 777) doing this CI jiggle to approximate the 290 kias descent?
MG2
757 - fly econ (usually about 325) until approach asks you to slow down. Then just do a speed edit.
No jiggling in a critical phase of flight
10-05-2010, 09:25 PM
#13
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Originally Posted by MacGuy2
Follow-up on the follow-up.
Are any of the other FMS fleets (besides the 777) doing this CI jiggle to approximate the 290 kias descent?
MG2
Are any of the other FMS fleets (besides the 777) doing this CI jiggle to approximate the 290 kias descent?
MG2
10-06-2010, 06:54 AM
#14
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Originally Posted by hyperone
MD-11 descent speeds are usually programmed during the FMS pre-flight set-up, and are dependent upon the CI number assigned that particular flight.
If assigned a Mach cruise speed you program the FMS with a cost index of 200 and set "assigned mach"/290 for the descent. At level off set the assigned mach speed using a speed edit.
If assigned a Cost Index other than 200 you clear (if one was set) the "assigned mach"/290 out of the descent line and let it fly econ speed for all phases of flight.
10-06-2010, 09:53 AM
#15
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Dumb question? But does anybody actually know where the 290 came from... Wouldn't flying econ all the time be the most economical by definition? I used to think it was some sequencing/timing thing but I don't think that is the case. Anybody know? 
10-06-2010, 02:09 PM
#16
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Originally Posted by USMCFDX
From the 777 Comm Notes:
2) There are a lot of questions about the 290 knot decent into MEM. The FOM is a bit misleading in that we don't have any other cost index other than 150 which we all know will yield a 314 knot descent. We want to keep thinking cost index for the day when we have dynamic cost index capability so the correct procedure should be adjusting cost index prior to decent to result in a 290 knot decent into the MEM area. A good technique is to open the speed window when within 50 miles of TOD, adjust CI to result in a ECON DES speed of M83/290. At TOD, close speed window to allow FMS to control speed for the decent. If you are too close to TOD (15 mi or so) you can no longer adjust CI, and have to just stick M83/290 in the ECON DES page as a manual decent speed, no style points there.
2) There are a lot of questions about the 290 knot decent into MEM. The FOM is a bit misleading in that we don't have any other cost index other than 150 which we all know will yield a 314 knot descent. We want to keep thinking cost index for the day when we have dynamic cost index capability so the correct procedure should be adjusting cost index prior to decent to result in a 290 knot decent into the MEM area. A good technique is to open the speed window when within 50 miles of TOD, adjust CI to result in a ECON DES speed of M83/290. At TOD, close speed window to allow FMS to control speed for the decent. If you are too close to TOD (15 mi or so) you can no longer adjust CI, and have to just stick M83/290 in the ECON DES page as a manual decent speed, no style points there.
Frank, it was my understanding that the original 290 was because someone thought that would be a money saver and because the 727s who were descending a the speed of heat were eating up the Airbus fleet which were descending at C-150 speeds thus causing all sorts of headaches for ATC. Also, during the day recovery, the NWA bubbas were arriving at about 280 kias so all of our fleet was eating them up. Check with you next crew bus driver, he/she may have more accurate info on this topic.
MG2
10-07-2010, 10:07 AM
#19
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Mac, Thanks. I still wonder who came up with it?
Sidenote: the Airbus actually likes 315 to 325 for descent (or so says the FMS). Well except with that d@mn 55 index then it likes to go backwards.. It usually falls between 270 and 280 with the 55..
Sidenote: the Airbus actually likes 315 to 325 for descent (or so says the FMS). Well except with that d@mn 55 index then it likes to go backwards.. It usually falls between 270 and 280 with the 55..
10-07-2010, 10:35 AM
#20
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Originally Posted by FrankTheTank
Mac, Thanks. I still wonder who came up with it?
Sidenote: the Airbus actually likes 315 to 325 for descent (or so says the FMS). Well except with that d@mn 55 index then it likes to go backwards.. It usually falls between 270 and 280 with the 55..
Sidenote: the Airbus actually likes 315 to 325 for descent (or so says the FMS). Well except with that d@mn 55 index then it likes to go backwards.. It usually falls between 270 and 280 with the 55..
As to who actually came up with the 290, I'd speculate that it was either JB or PC. But I don't know that for sure.
MG2
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