What are the realistic fuel reserves when landing?

[Boeing or not going 578]

When flying an international flight, what are the average reserves you would expect to have? I am landing with 9 or 10 kgs of fuel left, the sensor warns you with 6. So should I have less than 9 or 10? These are ETOPS 120 flights so I am thinking that extra fuel is required. I'd like to get a better understanding for how much fuel I should be loading so I don't waste money! Thank you!

 

David Frank

[PHXMD-11 86]

When flying an international flight, what are the average reserves you would expect to have?

 

If you are flying under the FAR Flag policy (international flying on an airplane registered in the US) you should have enough fuel to fly to your destination, fly 10% of the time between departure and arrival, then fly to an alternate airport (2 hours if no alternate planned), fly for 30 minutes while holding.

 

If you are flying under EU policy, you should have enough fuel to fly to your destination, then continue on to an alternate airport, fly for 30 minutes as reserve, and any extra fuel you desire. Contingency fuel requires either five percent of the total fuel needed to fly (this can be reduced to 3 percent if an alternate is planned), and enough fuel to fly for 20 minutes.

 

As you can tell, it is difficult to say what's normal because every flight is different. Winds, temperatures, routes, weight, MEL items, and drag notwithstanding.

[77west 139]

I usually take what PFPX tells me and add a ton or two depending on length of flight. Usually land with around 7 or 8 tons.

[hopskip 253]

Using PFPX, you can select which reserve rules you are using. EU-ops, US Part 121 Jet, Australian CASA, ICAO International. American FAA aircraft overseas, etc.

 

I usually pick the reserve rules required, and add about 15 minutes extra fuel (also letting PFPX determine how much that is). so that is to say, I usually carry close to minimum reserves (with an alternate picked) plus 15 minutes.

 

In good weather with close alternates, this usually lands with between 4.5 and 6.5 Metric tonnes. (depending on which rules are being used, and how far alternates are, and how long the flight itself was (5% rule = bigger flight = bigger number 5% is).

 

For some events, like VATSIM etc, I may also add a 30 (or sometimes even more) minute holding pattern planned, 40 minutes of taxi fuel and so on... but for a run of the mill point-to-point with an accurate weather prediction and good weather at destination. 15 mins extra is enough.

 

Of course if the weather at arrival is sitting near minimums, rain, gales, etc, then choosing a "good weather" alternate can become quite difficult. Still letting PFPX do the fuel calculation though, just sometimes "guiding" its selection of alternate to something different to, say, blizzards with cloud broken 50ft, overcast 100ft, visibility 1/16th mile, vertical visibility 75ft, wind 360/35G55 Runway 27/09. (hovering the mouse over the 4 auto-picked ICAO codes for Alternates shows the METAR and TAF in the popup).

 

FMC entry for reserve fuel is then "Alternate fuel (in kg/lb)" plus "Minimum Reserve (kg/lb)" the 5% contingency and holding and extra fuel not included in that particular number. That way you only get the "Insufficient Fuel" messages in the FMC when you burn through all your contingency and extra and holding fuel and now have to divert.
Ideally you want to divert when you see the "Insufficient Fuel" message, which should mean you can fly to the alternate and land with your Minimum reserve fuel still in the tanks.

 

If you want to add "a ton of fuel" to your pfpx calculated, add it to the PFPX "extra fuel" field. That way it will take into account the increased fuel burn you get when carrying extra fuel.

 

It's never a good idea to lie to PFPX, because then it doesn't work.

Don't tell PFPX you are departing in 40 minutes time when you are actually departing in 3 hours from now.

Don't tell PFPX that you are using the real world weather when you are not.

Don't tell PFPX that you are using cost index LRC, when you are actually using Cost Index (anything else).

Don't tell PFPX that you are flying with 188.1 Tonnes ZFW when you actually have 209.3

Don't tell PFPX you are departing with 48.7 tonnes of fuel when you are departing with 49.7

 

Garbage in, Garbage out.

 

Actually interact with the software.

Yes let it spit out suggestions (random ZFW load, Bunch of Alternate airports, routes, etc)
but if you intend to do something different, actually enter the information that is consistent with your intentions.

 

Not departing this hour? change the Departure Time in PFPX.

Using a specific cost index that isn't LRC? enter that cost index in the appropriate field.

Uploading 1000kg of extra fuel? tell PFPX that in the extra fuel field (weight).

[scandinavian13 5,192]

 

 

It's never a good idea to lie to PFPX, because then it doesn't work.
Don't tell PFPX you are departing in 40 minutes time when you are actually departing in 3 hours from now.
Don't tell PFPX that you are using the real world weather when you are not.
Don't tell PFPX that you are using cost index LRC, when you are actually using Cost Index (anything else).
Don't tell PFPX that you are flying with 188.1 Tonnes ZFW when you actually have 209.3
Don't tell PFPX you are departing with 48.7 tonnes of fuel when you are departing with 49.7
 
Garbage in, Garbage out.

 

YESSSSSSSS!  Brilliant explanation.  B)

[Boeing or not going 578]

Thank you Trent that was very informative. I am not familiar with ETOPS planning and noticed large differences in fuel listed if I select the wrong alternative airports. I once had one plan from Africa to Reunion give me 40kgs more fuel.

 

All the info is going into PFPX correctly, cruise alt, weight, departure time, real weather. I wanted to make sure landing with 9 or 10kgs fuel was normal for long range etops flying.

[scandinavian13 5,192]

 

 

I wanted to make sure landing with 9 or 10kgs fuel was normal for long range etops flying.

 

...and then we complicate matters more by mentioning that different airports have different fuel prices.  As such, you might "tanker fuel," or fly with a bunch more fuel on the flight to that airport so that you don't have to buy as much at that airport with super expensive fuel.

 

Basically, the answer to your question is "realistic reserves" are highly variable.  You're never going to see a set number.  Realistic reserves to Hawaii from LAX are very high (there aren't too many alternates for a 777, or other large aircraft, so you're going to carry more to get to an alternate that's much farther away).  Realistic reserves to DC are are smaller since we have 3 international airports within a reasonable distance, but far enough apart that the weather could be bad at one and okay at another.