Hello, I’m flying with 321 and 777. In 777, I want to use CI 9999 and in 321 I want to use CI 999, but I can’t enter it in Simbrief. Can you solve this problem?
Why are you using such a high cost index? Anything above 200ish won’t have any additional effect, definitely not when into the thousands
actually, I’m flying toliss 321 and the flightfactor 777. There are difference between CI 100 and 400, and in ff777v2, 2000 and 3000 has significantly difference. That’s why I think I need the high CI.
In Boeing’s FMS manuals for the 777, they don’t publish data for CIs above 1000.
Actually, the reason I use cost index 9999 is that I have checked my FCOM, And it tells me from 0 to 9999 all of them is valid. I don’t have an English FCOM, but please see this translated from Chinese.
At work, for our 777F, we plan a CI of 150; which is right around the LRC speed for the 777. I was working a flight, roughly 15 hours long, and the operations controller wanted to speed the airplane up to make up a little time, so I ran a plan at CI-1000.
To save 12 minutes; it would have cost over 10000 lbs of fuel; as the increase in fuel burn goes up with the square of the airspeed; as the parasite drag increases exponentially.
Needless to say, we didn’t do it that day.
OK, Now I learnt that. but actually, I have an interesting question want to ask. This is not a simbrief problem but it actually impact on my flying very much. I was flying a long flight that day, And using CI 999, that’s a really big CI. But the plane flies slower and slower during the flight. At first that is about .85 but about 8 hours later the speed is only about .81. I thought that is strange. As you a real pilot, I want to ask that in econ mode with CI 999, is that normal like this speed decrease?
It depends
On what weight units, lb or kg; Boeing’s manual, for cts/lbs, a CI-1000 should be around M0.84 at 350, based on gross weight.
That being said I do NOT trust any flight model for any Flight Sim unless they used manufacturer data for performance; and I doubt many have the Performance Engineer’s Manual…
Yes, I don’t have that manual so that I can’t find the data of the performance. But I think a 777 only fly .81, that is almost slower than a 320.