Jlonchambon

b-777 DEFAULT FMC FUEL RESERVE

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Is there a way to set a default fuel reserve in the FMC INI page.

in my case, I load the proper fuel quantity in the tanks which includes extra contingency fuel. So I don't need an FMC fuel reserve in the INI page. That would prevent getting "Insufficient Fuel warning", and making the entry unnecessary in the INI page. 

I couldn't see a way to do it in the set up area.

thank you

J Lonchambpn

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without discussing any operational things you could try inserting a value and saving this new panel state. But I can't tell you if it will keep it.

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16 hours ago, Jlonchambon said:

in my case, I load the proper fuel quantity in the tanks which includes extra contingency fuel. So I don't need an FMC fuel reserve in the INI page. That would prevent getting "Insufficient Fuel warning", and making the entry unnecessary in the INI page.

If you want to avoid the message, you have two options:

Properly plan your fuel; or

Set the RESV value to 0 when you fill out the PERF INIT page.

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I

Thank you for your reply.

I have been doing all of the above.

So I presume that the FMC was designed by the manufacturer or PMDG  with no default réserve fuel setting.

Do you know the manufacturer of the FMS. (Smith May be ...I don’t know)?

anyway, PMDG did a great job creating the B777. I enjoy it greatly.

 

J LONCHAMBON

 

 

 

 

 

 

 

 

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On 2/12/2019 at 10:59 PM, Jlonchambon said:

I load the proper fuel quantity in the tanks which includes extra contingency fuel.

 

On 2/12/2019 at 10:59 PM, Jlonchambon said:

That would prevent getting "Insufficient Fuel warning"

These two things (with some exceptions) seem somewhat incompatible, no?

There is no 'default' figure here because the entry, typically, will vary from one flight to another. Different operators will have different standard procedures for what to put in there, but commonly it would be the final reserve fuel (generally 30 minutes worth) plus the alternate fuel. If the FMC predicts that you will have less than this value on arrival at your destination then it will alert you so that you can decide what do do about it.

If you are indeed loading sufficient fuel for the flight but are getting the insufficient fuel warning regularly once you have updated the FMC with the appropriate en-route winds, then either

- You are not entering a sensible value in to the RESERVES box, or:

- You are burning more fuel than you thought or your fuel planning is for some reason inaccurate...

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On 2/13/2019 at 5:50 PM, Jlonchambon said:

So I presume that the FMC was designed by the manufacturer or PMDG  with no default réserve fuel setting.

Do you know the manufacturer of the FMS. (Smith May be ...I don’t know)?

I'm not sure any aircraft has this. The value changes per flight. It would be like setting a default ZFW - you're going to overwrite it 99.9% of the time.

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Thank you genlemen for your comments.

I forgot to mention that I use PFPX as flight/fuel planner, and use PMDG B-777 aircraft.

You are right, each operator has its own fuel reserve procedures.

So each operator should be able to set their own standard reserve in the FMS once.

That was my hope.

I my case, I would want to set ZERO as my  standard procedure., and let PFPX compute  the required fuel. 

But If I want to set, say - 10000 LBS as my standard/default, then it would show such each time I launch the aircraft.

Thanks again

Jacques Lonchambon

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12 minutes ago, Jlonchambon said:

You are right, each operator has its own fuel reserve procedures.

So each operator should be able to set their own standard reserve in the FMS once.

But that's not possible, because as I explained above, the entry (in kgs/lbs of fuel) is never going to be the same from one flight to the next, even for the same operator.

It would be very unusual for any operator to enter anything other than at least final reserve + alternate fuel. Final reserve fuel is time-based (generally 30 or 45 minutes of holding at 1500 ft above the destination aerodrome) and so will vary (admittedly only slightly) depending on the conditions on the day. Alternate fuel, however, is clearly going to change (possibly quite significantly) every single flight depending on where the alternate is located and the expected weather conditions, so there's no way you could put a standard figure on that.

18 minutes ago, Jlonchambon said:

I my case, I would want to set ZERO as my  standard procedure., and let PFPX compute  the required fuel. 

I'm not quite understanding why you feel that having an entry in the RESERVES field in any way interferes with PFPX's fuel calculations?

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I was talking about Default reserve on the FMS. If I could set say 8000 as default and it would stay there  each time I turn on the FMS, I would not have to reset it each flight thus would not get that ennoying "insufficient fuel" all the time.

A standard fuel reserve is an arbitrary number and is in additon to the required fuel. It is usuallty the same. Each crew knows they would have the 8000 lbs extra.

Reserve fuel (in my experience) is in addition to normally anticipated delays, diversion to alternates, holding there, and legal additionlal fuel or US Flag rules fuel.

It's not a big deal.

 

Thanks again for your comments.

 

Jacques Lonchambon

 

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