Calculating correct Reserves

[downscc 1,327]

That's an interesting bulletin I've not seen, thanks Marius.  It reminded me of the time I had to declare "minimum fuel,"  in an AF Aero Club Arrow landing at Scott AFB  picking up ice on my leading edges while the controller there were notorious for holding aero club aircraft on an extended downwind if there was "real traffic" within 40 miles.  We exchanged some words once I was on the ground because I was getting near empty.  The "emergency fuel" declaration was a pretty common thing among F-4's landing at Ramstein AB... those birds have enough fuel to get them on target and back home with minimum delays... if four or five of them stacked up waiting their turn on the GCA at least one of them would go "bingo" which was the term used to mean they need to land or punch out.

Edited May 29, 2018 by downscc

[BlueStar 323]

4 hours ago, downscc said:

aiting their turn on the GCA at least one of them would go "bingo"

Dan,

In SE Asia I have been 10 minutes into a 20 minute fuel light on a GCA to minimums into Phu Bai or Da Nang on several occassions. Not something to be proud of but it came with the territory.  I swore that when I got back to the "World" I would never put myself in that position again. 🙂

[trisho0 23]

23 hours ago, downscc said:

It's simple and works for you, but you are missing out on a valuable management tool.  I use the amount of fuel that the flight plan projects will be remaining if I don't use any contingency or rerouting, and therefore if the fuel remaining message appears it acts as a precautionary notice to take a look at what's trending.  Perhaps the winds are not as favorable, or there is a mechanical/performance issue. Often I'll see the message early in the flight during climb to cruise, where I ignore it and it goes away once established in cruise.  Regardless, things are not as planed and it's good to know why.  It's a simple matter to adjust the reserve value on the PERF page to accommodate whatever is going on, for example I might change it to a lower amount that leaves me with 45 min reserves if the winds are unfavorable.

CI 85 is different in the 737 than it is in the 747 or 777.   I'll use 40-80 in the Queen and often use 220 in the 777. These aircraft have different CI ranges.... most of my B736 BBJ flying is CI=80 (very fast), but if I'm flying an airline route I'll dial it back to 35-45 in the NGX.  Again, you're not wrong but you have simplified the process to make it extraneous to mission accomplishment.

Many thanks for your great help! I will see what I get then with CI 40 for 737NGX but keeping Reserves 5 right? Also, CI 220 for the 777 not too high?

[trisho0 23]

23 hours ago, Marius_S said:

https://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info/all_infos/media/2008/info08004.pdf

Beautiful info …. thanks

[berts 97]

There have been some very interesting points raised in this discussion and if I didn't know any better I would now be very confused as to what my Reserve Fuel actually is.

By keeping things simple we are less likely to get caught out, so it is important that we always use the correct Reserve Fuel figure as calculated in our Fuel Flight Plan and not, as some have already suggested, use whatever 'tickles our fancy' or change it later if we divert (this is what Contingency Fuel is for; i.e. to cover unforeseen variations from the planned operation and it is this fuel that can all be used up at any time after aircraft push-back or engine start)

Reserve Fuel is a planned fuel figure and it is defined as the minimum fuel required to be remaining in tanks at a normal landing.

However, this definition may vary depending on the Authority's Regulations (e.g. FAA) under which the aircraft is operating and it may also depend on type specific factors, such as an allowance for unreliable or unuseable fuel, gauge configuration errors etc.  For example, in the UK Reserve Fuel is calculated as the quantity of fuel required in the tanks equivalent to holding at the Alternate (or the Destination if no Alternate is available) for 30 minutes at the planned holding weight, with the aircraft clean at 1,500ft AGL.  So, if you are landing at your normal Destination with an Alternate available you should expect to land with at least your Diversion Fuel plus your Reserve Fuel (you might have some or all of your Contingency fuel as well).

Bertie G 

[trisho0 23]

Reserve and Cost Index are calculated for emergency fuel too? If so, that is the reason why my birds never had side effects with my settings as Reserve 5 and Cost Index 85. I did Reserve 5 and CI 220 with PMDG T7 and found no differences. I have to mention that I use ILS landings. Barely I do manual landings (I need more practice).

[trisho0 23]

57 minutes ago, berts said:

it is important that we always use the correct Reserve Fuel figure as calculated in our Fuel Flight Plan

I am new on this step. How do you calculate? Is it explained in the manual? If so, what page?

[BlueStar 323]

13 hours ago, trisho0 said:

Reserve and Cost Index are calculated for emergency fuel too

I use the minimum legal reserve for my Reserve setting on the scratch page PERF INT.  Some captains use more, it's a personal preference thing and only a reminder.  I never leave operations until I'm happy with the planned fuel for the flight.  The last thing I want to do is have to file an ASRS or have my heels locked in front of the CP's desk because the fuel got screwed up. 🙂

The cost index used is the one flight planned.

Edited May 31, 2018 by Bluestar

[trisho0 23]

4 hours ago, Bluestar said:

The cost index used is the one flight planned.

Please, can you detail? When I do flight plan I enter FMC info Departure/Arrival and waypoints accordingly. But, for CI input I use 85 for 777 - 747 and 40 for 737NGX, leaving entered Reserves at 5 for all PMDG planes. I learned also I should enter CI 220 just for 777 but either entries work for me. 

[BlueStar 323]

On ‎1‎/‎21‎/‎2018 at 4:57 PM, skelsey said:

Under normal circumstances you should touch down at your destination with at least final reserve + alternate fuel

Simon,

One of the real world problems that is not a problem in flight sim is fuel density.  Ten thousand gallons of Jet A may weigh 69,000 lbs. in one corner of the world, but it may only weigh 65,000 lbs. in another part of the world.  That difference can make a substantial difference in range. 

[Budbud 227]

1 hour ago, trisho0 said:

Please, can you detail? When I do flight plan I enter FMC info Departure/Arrival and waypoints accordingly. But, for CI input I use 85 for 777 - 747 and 40 for 737NGX, leaving entered Reserves at 5 for all PMDG planes. I learned also I should enter CI 220 just for 777 but either entries work for me. 

Hi Wilhelm,

There is no one CI for an aircraft type but CI range. If I recall well, CI for 747 and 777 range from 0 to 9999 (values accepted by the FMC).

The CI is a financial value and is calculated by the company. The higher the CI, the faster the aircraft but also the higher the consumption. Airlines may define different CI for the same aircraft depending on the line, the delays and other paramaters that I don't have in mind.

Here is a post that listed the CI of some airlines years ago. The CI must have likely changed since as the fuel prices varied.

But It illustrates the way the CI may differ.

 

As for the reserve value in the FMC, I'm not a real pilot but I'm used to enter the final reserve (30 minutes as per European/ICAO fuel policy) + alternate.

Edited May 31, 2018 by Budbud

[downscc 1,327]

1 hour ago, trisho0 said:

I should enter

You misunderstood me.... there is no CI you should use.  Each company has its own CI policy and at some this may change daily.  I use 220 in the 777 simply because I want the speeds associated with this.  Romain beat me haha.... what he said.

[berts 97]

21 hours ago, trisho0 said:

I am new on this step. How do you calculate (Reserve Fuel)? Is it explained in the manual? If so, what page?

The Reserve Fuel figure to use will be shown on your Flight Plan.  If you want to calculate it manually then you will need to obtain a set of Performance Tables for that aircraft type.  As a general guide, the B744 uses approximately 9,000Kgs fuel per hour at a typical landing weight, so your minimum Reserve Fuel figure is likely to be in the region of 4,500Kgs - give or take a few 100Kgs either way.  The Cost Index to use in the FMC (anything from 0 to 9999) will also be published for the flight and it is used to calculate the aircraft's ECON speeds for the flight.  A Cost Index of 0 will result in minimum trip fuel for the flight and therefore maximum range.

You will sometimes see a Flight Plan which also shows a Total Reserve fuel figure as well, in which case this higher figure may be input into the FMC. This Total Reserve figure can be generated for a number of operational reasons, such as Island Reserve where there is no suitable Alternate, or perhaps on a long range re-clearance operation where an en-route alternate is nominated as the initial destination, but always intending to land at the scheduled destination.  Most 744 pilots I know are definitely more comfortable landing at their planned destination with more than Reserve Fuel - i.e. at least 10,000Kgs in tanks!

Bertie     

[trisho0 23]

5 hours ago, downscc said:

You misunderstood me.... there is no CI you should use.  Each company has its own CI policy and at some this may change daily.  I use 220 in the 777 simply because I want the speeds associated with this.  Romain beat me haha.... what he said.

I see now … more clear. So, I can use 85 or 220 for the T7 but which value could speed up the plane flight? I mean, which value makes it faster speed in flight?

[trisho0 23]

3 hours ago, berts said:

The Reserve Fuel figure to use will be shown on your Flight Plan.

Oops! I am so sorry is my ignorance on Flight Plan. I thought a Flight Plan means the process of entering info into FMC like Departure/Arrival by entering ICAO and selecting sequential of waypoints. I must be very wrong I know.

Where to see the Flight Plan really? I don't see any tool in PMDG package to make Flight Plan except via FMC.