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"fmgc_idle_fac" and "fmgc_perf_fac" ?


Stu Antonio

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Stu Antonio

fmgc_idle_fac=
fmgc_perf_fac=

What are those entries in the aircraft config setting?
Can't find anything in the Aircraft Options pdf....

Greets,
Stu

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Stu Antonio

I see. But what exactly does it mean for the aircraft? And how do I know what to set here? For example I‘ve downloaded 2 321 liveries, one with =0, the other one with =3. Is this related to airframe age? 

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M_i_k_e_V_o_g

Done by engineering.
Perf factor is shown on the ofp though, so if there is a discrepancy it is to be resolved with dispatch and changed if necessary.

Amending the PERF factor is made to account for airframe/engine specific deterioration and therefore increased fuel burn from the std. Amending or updating the IDLE factor is to adjust the FM descent profile. If it is thought to be incorrect and the aircraft is descending too early, too late etc.

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  • 9 months later...
Cathal Kavanagh

Quick question, should we update the Fuel Factor option on Simbrief with the value for fmgc_perf_fac= 

 

? Or should simbrief be set to a particular setting for accurate fuel burn logging from the flight plan?

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Koen Meier
27 minutes ago, Cathal Kavanagh said:

Quick question, should we update the Fuel Factor option on Simbrief with the value for fmgc_perf_fac= 

 

? Or should simbrief be set to a particular setting for accurate fuel burn logging from the flight plan?

Simbrief should be set to the perf value that the aircraft has but you might need to tweak in the end as the fuel burn isn’t entirely accurate I feel.

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Cathal Kavanagh
On 10/25/2020 at 10:49 PM, Koen Meier said:

Simbrief should be set to the perf value that the aircraft has but you might need to tweak in the end as the fuel burn isn’t entirely accurate I feel.

Hi Koen,

 

Any tips on how to calculate additional fuel burn % from the FP when logging burned fuel? I'm trying to get as accurate as possible a fuel factor.

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Simon Kelsey

I have to say that as far as the IAE engines are concerned my Simbrief fuel figures are always pretty much spot on, within 100kg or so most of the time, provided the Simbrief fuel factor matches the FMGC PERF factor.

I rarely fly the CFMs so I'm not sure how it stacks up for them!

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Camille MOUCHEL
20 hours ago, Simon Kelsey said:

I have to say that as far as the IAE engines are concerned my Simbrief fuel figures are always pretty much spot on, within 100kg or so most of the time, provided the Simbrief fuel factor matches the FMGC PERF factor.

I rarely fly the CFMs so I'm not sure how it stacks up for them!

i fly only CFM and the same, I did a flight from AZ to B fully managed in climb and descent and speed, and difference was within 100kg, the difference is only due to the taxi fuel, i always plan 200Kg of fuel but most of the time, i used 80-120kg so i always have in avg az surplus of 100kg when taking off

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