Mach Number calculation on Cost Index
 

How cruise mach number could be calculated if particular Cost Index is given? For instance there is no mention of Cost Index at all in FPPM of B737-300-400-500, B763 and a brief mention of it in B772 and B744 FPPMs.

Am I correct that mach number and fuel flow for given CI can be somehow calculated by adjusting data from Long Range Cruise tables? If so, then how?


Thank you

You need to obtain the applicable Performance Engineering Manual for the aircraft, it usually has Cost Index Charts.

Mutt

How would dispatchers make their computations, if most operators use ECON mode with CI, not LRC which is described in FPPM? I assumed that FPPM is exhaustive document containing all relevant data for flight planning.

"How would dispatchers make their computations" - By referring to the Performance Engineering Manual, refer to Mutt's post.

It ain't rocket science, for one aircraft that did not have such info in the PEM, I was tasked with writing a computer programme to calculate CI. Inputs are normal FPPM performance, Fuel cost, Non-Variable Overheads etc., a quite straight-forward task:ok:

Regards,

Old Smokey

Old Smokey

I have to disagree with you (respecfully... and carefully :))

Finding the real CI requires rocket scientists. It can be very complex to assess the exact operational cost of one flight minute. In addition, the CI will vary depending on each particular route, even in the outbound and inbound sector for a given destination, and depending on the variable price of fuel.

Now, if you tell me that CIs can be easily calculated with a small error margin... Maybe, but even though, most airlines simplify the question too much. They use a fixed CI for every flight, and it remains constant for years, no matter what happens with fuel costs.

In A320, they say that CI 45 cruise MN is approximately equivalent to LR cruise MN. Taking into account that most airlines have CIs well below that, airliners are flying very close to maximum range (CIs of 20, 15 or even 10 fuel Kg worth each minute).

My question is rather different. I need to calculate mach number and fuel flow on GIVEN CI. No FPPM states how to obtain these two values, apart from B744 FPPM: it gives % fuel and time adjustment for different CI. What's interesting, is that these two adjustments are made from LRC values. So supposedly you can calculate mach number and FF for other boeing acft types based on FPPM published LRC values. The question is - what are these adjustments for each acft, for example B737CL&NG, B763, B772?

Perhaps data I need is contained in Performance Engineering Manuals, could anyone share? I'm willing to pay (PEM for any Boeings & Airbuses). Please PM me.

So its official, Old Smokey is a rocket scientist :):):) :ok:

GSLOC, its only available in hard copy so you have to ask Mr Boeing. Failing that you can cheat, use your flight planning system to run specific CI values and tabulate the data :)

Mutt