Question: Cost index units?

SimBrief Dispatch
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  1. Is Simbrief always using the same units for cost index regardless of units settings in Dispatch (metric vs. imperial, or lb/h vs. kg/min)?
  2. Is there a way of knowing what units are used for cost index for a particular Simbrief aircraft profile?
  3. More of a real-world question maybe, and might void question 2: Would all operators use the same units for cost index for a particular manufacturer (e.g. Boeing vs. Airbus), or do the manufacturers provide cost index data in different units letting customers choose what units they use?

Thanks!

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Hi,

Yes, currently SimBrief always uses the same CI units (regardless of the flight units setting). The units used depends on the aircraft, most Airbus use kg/min and most Boeing use lb/hr, but I don’t recall the specifics for individual aircraft.

I don’t know the answer to your third question unfortunately, perhaps one of the real world dispatchers on here can chime in if they know.

Best regards,

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Perfect, appreciate it. So basically, this is not something I need to worry about and that is good.

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For example at my airline, a US-based 121 box-hauler, we use

  • B777 - CI150
  • MD11 - CI75
  • B75/B76 - CI80
  • A300 - CI55

All those values are are Long Range Cruise (LRC, 99% of best fuel mileage), but flown in CI so as to take advantage of the ECON optimization routines in the FMS. They never change based on the operating cost of the flight. Our FPS also has a “VCI” mode, which attempts to drive an on-time arrival, so some days if I select VCI on a US domestic flight, the resulting CI could be very low, or very high (depending on the winds aloft). We also have a band of acceptable CI results so the flight planning system wont drive too slow a CI, or too fast of a CI.

Since we are a US operator, all our CI values are operating cost-hr divided by fuel cost cents/lb.

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