Fuel Management

[loveclose]

Just discovered after quite a few years of FSX-ing (and now on the Steam Edition) the knee board notes durng flight. Have just flown 1000+ nms and have noticed the estimated airspeeds and fuel burn for each waypoint updated each leg as it were.

I have a number of queries all related to fuel management and time - I realised half way through my flight that I was going to run out of fuel and did my best to make my destination by flying slower to reduce fuel burn. I would have been dumped in the drink 80 nms short of my destination.....so I failed!! So the questions:

1) I'm flying just under the speed before I get overspeed warnings whcih in this aircraft was 345 knots. On my notes I see that I'm estimated to make a ground speed of 460 knots and my actual ground speed is recorded as being 360 odd - how am I supposed to make a ground speed of 460knots when I'm right at the point where overspeed warnings occur.

2) I'm burning almost three times the amount of estimated fuel - partly because I'm flying slower than my estimated speed as quoted on the notes. Time is taking longer than estimated, so again I'm burning more fuel. If I slow down, the fuel burn rate is reduced but I'm burning fuel for longer for that leg.

The long and the short of it is that I'm nowhere near my estimated ground speed, and at my maximum non-overspeed I'm buring fuel up quickly and not making the estimated time.

Any suggestions on how to manage fuel in this situation would be appreciated.

Lastly - I arrived at my aiport (unbenownst to me, the unlimited fuel setting was on!). I called for a fuel truck to be told that 'there are no fuel trucks at this airport'.....how do you refuel at such an airport??

[EbonHawk]

As for refueling, you have to either plan for that, or cheat. Your call. Just like in real life, not all airports have fuel available, in any form.

[APUtech]

loveclose, my best answer in this case is for you to be advised that the fuel calculations in FSX's flight planner are way off, and it may serve you to look up fuel consumption data at various phases of fight for your particular aircraft.

I fly 747's most of the time and I find that they consume anywhere from 24,000 lbs fuel per hour--6,000 lbs per engine--to 28,000 lbs per hour--7,000 lbs per engine, per hour, depending on flying conditions (head/crosswind/tailwind).

Typically I will take into account the overall duration of the flight in hours or fractions of hours and plan my fuel load accordingly, adding in fuel consumed during climbout, and at least an hour-plus in case I have to go around or divert (for me, it's like 1 hour 45 minutes reserve fuel during the day and 2 hours reserve during night time operations).

If you can't find readily available fuel consumption tables for your particular aircraft I would suggest monitoring your fuel usage during a flight at cruise and seeing how much fuel is consumed, noting the fuel flow levels at cruise power settings per hour, per engine. You can take this a step further and monitor your fuel flow during climbout (which can be almost double the rate as is cruise) and using a bit of extrapolation or good guessing, figure out how much fuel total you will need for your flight.

If you have questions I'd be happy to answer them via chat.

Happy flying.

APUtech

[loveclose]

Thank you both for your replies.

I wondered if the FSX log was way off!!

The ground speed data was slightly more perplexing as I can't see many aircraft given to us making an actual ground speed of 460 odd knots as the overrspeed warning snaps in a good 100 knots earlier.

I'm certainly going to try and build up some fuel consumption data as suggested. I've just managaed to get my FSX working again after some glitches running it under Win10 - out of system memory bits - so now that I've got it working again and it's runnign a good couple of hours without crashing (over heavy detailed terrain such as New York), I've got the confidence that my system isn't going to crash out on longer flights.

Any other discussion on this topic welcome - I am going to start building my own data charts based around the FSX ones, and start as suggested getting some cruise burn data for various cruise speeds for each aircraft I commonly fly.

Happy Days!

[EbonHawk]

I would like to recommend a standalone (but can be integrated with a little effort) program called Plan-G http://www.tasoftware.co.uk/

I automates a lot of flight planning and is very powerful. I know there are several out there right now that are also free, but Plan-G is a godsend. You can set all kinds of parameters in it and it makes flight planning very helpful. It can give you much more accurate fuel consumption predictions than FSX's default flight planner can. You can also add in the data you get from your own testing flights you plan to do anyway.

And with the integration with FSX feature, you can have it tied in with your flights and show you the information in real time.

[Nightmare1964]

Flight plan every flight so that you land with at least 45 minutes of fuel on board.

If the weather at your destination has a dodgy weather forcast for when you plan to land, plan an alternative to divert to another airport with a good weather forcast, and still have 45 minutes of fuel on board. It is also good flight planning to have 10% extra fuel on top of this as a further safety measure.

You may also plan for holding fuel.

Know your fuel burn.

Plan your fuel for the time it takes to get to the destination, not distance. If you are travelling slower, then your fuel burn will be greater. My suggestion would be to do one or more trips at that speed and record how much you used and convert it to hourly consumption. If you include taxi, climb and descent in this calculation, you'd have a good guide for flight planning.

[rjlfry]

The range is based on aircraft+payload real pilots never fly at max speed they would be fired.
cruise is much like a car drive at 60mph you get there drive at 120mph you arrive faster but burn more fuel.

[kwijiboenator]

Many people make the mistake of having too much fuel onboard when landing. Aircraft are difficult if not impossible to land when they're too heavy. They're designed to take off with a little too much weight, however, landing is a different issue.

[Nightmare1964]

Originally posted by kwijiboenator:

Many people make the mistake of having too much fuel onboard when landing. Aircraft are difficult if not impossible to land when they're too heavy. They're designed to take off with a little too much weight, however, landing is a different issue.

You are quite right, a lot of aircraft have a maximum landing weight as well as a maximum takeoff weight. But a lot, like my plane, these weights are the same for both take off and landing.

But I do know, if the weight is up near the MTOW, to get maximum fuel, I'll fill the fuel a little over MTOW for the taxi fuel, but it will be at MTOW when I line up for takeoff.

For safety, if the MLW is lower than MTOW, I would be taking off at MLW. What if you had to make an immediate landing for some reason shortly after take off?