Fuel Circles
Joined: Oct 2011
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From: UK
Interesting topic.
These fuel circles seem to do exactly what most of us probably have in the fuel column of our plog. These fuel circles are drawn on the chart(?). My plog for example has a fuel column at the end of each leg with how much I expect to use, and what I expect to have in the tanks. Both written in a box with a horizontal line as opposed to a circle. Now whether these 'estimations' are for the leaned engine or otherwise they work and will do just fine for my flying. Furthermore in the planning phase of the flight 45 mins extra fuel is added plus 10% of that again. So with that in mind I suggest the leaned/full rich figures wouldn't be too dissimilar for the GA hops we see around the UK, and if so the contingency will cover it.
On using the circles method: the red half of the circle seems to be drawn in red to be conspicuous. I would consider drawing the whole circle in black or blue regardless, as red wont be easily read in red light (night flying?). I'll also mention that if flying IFR then fuel circles may not be the easiest way to check fuel calculations. IFR flight = higher workload and tends to be more accurate due to the navigation aids, ATC, etc, and I personally believe the chances of getting lost whilst IFR are close to zero. The latter reason is my preference for not using circles drawn on the chart (as well as preferring as clearer chart as possible).
Just my thoughts
GW
These fuel circles seem to do exactly what most of us probably have in the fuel column of our plog. These fuel circles are drawn on the chart(?). My plog for example has a fuel column at the end of each leg with how much I expect to use, and what I expect to have in the tanks. Both written in a box with a horizontal line as opposed to a circle. Now whether these 'estimations' are for the leaned engine or otherwise they work and will do just fine for my flying. Furthermore in the planning phase of the flight 45 mins extra fuel is added plus 10% of that again. So with that in mind I suggest the leaned/full rich figures wouldn't be too dissimilar for the GA hops we see around the UK, and if so the contingency will cover it.
On using the circles method: the red half of the circle seems to be drawn in red to be conspicuous. I would consider drawing the whole circle in black or blue regardless, as red wont be easily read in red light (night flying?). I'll also mention that if flying IFR then fuel circles may not be the easiest way to check fuel calculations. IFR flight = higher workload and tends to be more accurate due to the navigation aids, ATC, etc, and I personally believe the chances of getting lost whilst IFR are close to zero. The latter reason is my preference for not using circles drawn on the chart (as well as preferring as clearer chart as possible).
Just my thoughts
GW
Thread Starter
Joined: Sep 2011
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From: Lincolnshire
Hi GW,
Yep, I draw my fuel circles on the chart, next to the heading line and the figures are in the direction of travel. They do of course make the chart busier but I draw them in an area I am not going to use. But thats the beauty of circles on the chart, they are there, to check as you are checking your route.
The ystem of the plog fuel column sounds exactly like my circles. In fact, to satisfy the CAA I write these estimations in both the plog as you do AND the chart. That way I am practising for my QXC and Skills test but also learning the "everything on chart way" so when i'm let loose in the sky with my licence, I can use this as it is my preferred method (not so much paper to lose in the cockpit).
So, your 45min extra fuel, that sounds as though its the same as my 15 litres minimum FOG, as that would give me about 30 mins airborne...
Yes, the minimum fuel is in red so to be conspicuous. Thats an interesting point about its use in night flying and IFR. Hadn't considered it before. I will have to ask my instructor whether in that case the entire circle and figures are in black...and bear it in mind when I can graduate onto those ratings!
GQ
Yep, I draw my fuel circles on the chart, next to the heading line and the figures are in the direction of travel. They do of course make the chart busier but I draw them in an area I am not going to use. But thats the beauty of circles on the chart, they are there, to check as you are checking your route.
The ystem of the plog fuel column sounds exactly like my circles. In fact, to satisfy the CAA I write these estimations in both the plog as you do AND the chart. That way I am practising for my QXC and Skills test but also learning the "everything on chart way" so when i'm let loose in the sky with my licence, I can use this as it is my preferred method (not so much paper to lose in the cockpit).
So, your 45min extra fuel, that sounds as though its the same as my 15 litres minimum FOG, as that would give me about 30 mins airborne...
Yes, the minimum fuel is in red so to be conspicuous. Thats an interesting point about its use in night flying and IFR. Hadn't considered it before. I will have to ask my instructor whether in that case the entire circle and figures are in black...and bear it in mind when I can graduate onto those ratings!
GQ
Joined: Apr 2002
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From: Surrey, England
Fuel management
Hi GC,
I have been reading this thread with interest. I note that you have been taught to put everything on your chart, rather than on a plog form. I was told off for doing precisely this by an instructor who was an ex RAF Group Captain, ex fast jet pilot, and a very senior test pilot. My point is that what the RAF does today will be anathema tomorrow. So don't regard it as gospell. It is only how things are done today in one organisation. Do listen to pilots from other spheres; they all have good things to teach.
As to the fuel check circles. As has already been said, these seem to fit the bill fine for fast jets and also for you - as long as you are only flying 50nm legs between quiet aerodromes with only a simple aeroplane and only you and perhaps your instructor aboard.
However, if you were to fly a four or six seater, with several tanks, over legs of 200nm or more and with three or four passengers and luggage aboard, I suspect this method of fuel management might soon prove inadequate.
May I suggest that you ask around at the club and see if there are any pilots there who have flown a Hercules or a Galaxy a Tristar or a Nimrod and ask them how they manage their fuel burn. Let us know what you discover.
I did ATPL groundschool about ten years ago, and the method of fuel management I was taught was based on airline practice, i.e. calculate taxi fuel, trip fuel to destination, fuel from destination to alternate, half an hour's fuel for remaining in the hold at the alternate, and then landing and taxi-in fuel; (not to mention any allowance for 'unusable fuel' and maximum permissable fuel load to remain under max landing weight). Obviously, you can't use this method on a Pa28, but it does at least provide the mental backgound for my fuel planning. Even in a small aeroplane I allow for taxi fuel and I do calculate my fuel from destination to alternate (just in case the aircraft ahead of me does a wheels-up landing on the only runway at my destination). I plan each leg of a multi-stage trip as though each was a separate trip. Yes it takes time, but it gives me confidence.
Regards,
Broomstick.
I have been reading this thread with interest. I note that you have been taught to put everything on your chart, rather than on a plog form. I was told off for doing precisely this by an instructor who was an ex RAF Group Captain, ex fast jet pilot, and a very senior test pilot. My point is that what the RAF does today will be anathema tomorrow. So don't regard it as gospell. It is only how things are done today in one organisation. Do listen to pilots from other spheres; they all have good things to teach.
As to the fuel check circles. As has already been said, these seem to fit the bill fine for fast jets and also for you - as long as you are only flying 50nm legs between quiet aerodromes with only a simple aeroplane and only you and perhaps your instructor aboard.
However, if you were to fly a four or six seater, with several tanks, over legs of 200nm or more and with three or four passengers and luggage aboard, I suspect this method of fuel management might soon prove inadequate.
May I suggest that you ask around at the club and see if there are any pilots there who have flown a Hercules or a Galaxy a Tristar or a Nimrod and ask them how they manage their fuel burn. Let us know what you discover.
I did ATPL groundschool about ten years ago, and the method of fuel management I was taught was based on airline practice, i.e. calculate taxi fuel, trip fuel to destination, fuel from destination to alternate, half an hour's fuel for remaining in the hold at the alternate, and then landing and taxi-in fuel; (not to mention any allowance for 'unusable fuel' and maximum permissable fuel load to remain under max landing weight). Obviously, you can't use this method on a Pa28, but it does at least provide the mental backgound for my fuel planning. Even in a small aeroplane I allow for taxi fuel and I do calculate my fuel from destination to alternate (just in case the aircraft ahead of me does a wheels-up landing on the only runway at my destination). I plan each leg of a multi-stage trip as though each was a separate trip. Yes it takes time, but it gives me confidence.
Regards,
Broomstick.
Joined: Oct 2011
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From: UK
As Broomstick above, fuel planning can be as intricate or simplified as you like. For me the A to B flight is calculate something like the following:
- taxi, take off, climb
- total route level (incl. descent)
- diversion
- contingency
- 10% of contingency
If it were a local flight for an hour or so, take off to landing, the aeroplane burns about 8USG/ph so as long as there are about 12-ish USGs in the tanks I'll fly and not worry about the in flight figures, only the time. OK so this relies on time keeping and knowing many local places to divert to should something happen, but I'm confident I know the area well enough
How you monitor fuel is a personal preference ultimately, and another of aviations great 'ifs'
- taxi, take off, climb
- total route level (incl. descent)
- diversion
- contingency
- 10% of contingency
If it were a local flight for an hour or so, take off to landing, the aeroplane burns about 8USG/ph so as long as there are about 12-ish USGs in the tanks I'll fly and not worry about the in flight figures, only the time. OK so this relies on time keeping and knowing many local places to divert to should something happen, but I'm confident I know the area well enough
How you monitor fuel is a personal preference ultimately, and another of aviations great 'ifs'
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I did ATPL groundschool about ten years ago, and the method of fuel management I was taught was based on airline practice, i.e. calculate taxi fuel, trip fuel to destination, fuel from destination to alternate, half an hour's fuel for remaining in the hold at the alternate, and then landing and taxi-in fuel; (not to mention any allowance for 'unusable fuel' and maximum permissable fuel load to remain under max landing weight). Obviously, you can't use this method on a Pa28, but it does at least provide the mental backgound for my fuel planning.
What I think is the biggest issue is that in GA most people don't know their fuel flow accurately.
I know nuffing about big jets but I am pretty sure they have accurate fuel metering (totalising) systems. They probably also have accurate fuel gauges.
But they are also hugely capable weather-wise (anti ice, FL350+ ceiling, autoland, etc) so a "30 minute" (or whatever) reserve for something is actually meaningful whereas in GA it is all but meaningless because 30 mins' flight is unlikely to get you out of a bad wx area.
Piston GA needs bigger reserves.
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From: Moray,Scotland,U.K.
Good point Peter, but piston GA vanilla PPLs ain't flying in bad weather to begin with
Avoid imitations
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From: Wandering the FIR and cyberspace often at highly unsociable times
Fuel circles are, as explained above, a circle with two fuel figures written in them.
Nothing to do with range rings on a chart!
When the sortie is being planned, the circles are left blank until just before the flight when the expected wind is applied to the flight plan. The figures are calculated and the circles filled in, working backwards, from the intended destination.
The top figure is the expected figure remaining, depending on how much was in the tanks at start up. The lower figure is the figure needed for the completion of the sortie as planned. The difference is (or was in my time) known by the RAF as "combat fuel".
The RAF taught it this way because when en route to a destination it often won't be refuelling (e.g. it will be carrying out a task such as dropping a bomb, or disembarking troops and then return to base or carry on to another destination). An easily assessed "running fuel plan" needs to be kept because if the aircraft was "bounced" i.e. attacked by an enemy, after the pilot had regained his composure, he would know if he could continue on his mission as planned, or not. In combat you can forget all ideas of economical cruise - it's throttles fully forward and mixture fully rich, not necessarily in that order. So, as soon as the position by the next fuel circle is regained, a rapid go/no-go decision could be made.
In the worst case the two figures would be the same, i.e. no "combat reserve" before start up. Having done much of my military service in a helicopter with a shabby 1 hour 25 minute endurance, fuel planning was always a major consideration.
Nothing to do with range rings on a chart!
When the sortie is being planned, the circles are left blank until just before the flight when the expected wind is applied to the flight plan. The figures are calculated and the circles filled in, working backwards, from the intended destination.
The top figure is the expected figure remaining, depending on how much was in the tanks at start up. The lower figure is the figure needed for the completion of the sortie as planned. The difference is (or was in my time) known by the RAF as "combat fuel".
The RAF taught it this way because when en route to a destination it often won't be refuelling (e.g. it will be carrying out a task such as dropping a bomb, or disembarking troops and then return to base or carry on to another destination). An easily assessed "running fuel plan" needs to be kept because if the aircraft was "bounced" i.e. attacked by an enemy, after the pilot had regained his composure, he would know if he could continue on his mission as planned, or not. In combat you can forget all ideas of economical cruise - it's throttles fully forward and mixture fully rich, not necessarily in that order. So, as soon as the position by the next fuel circle is regained, a rapid go/no-go decision could be made.
In the worst case the two figures would be the same, i.e. no "combat reserve" before start up. Having done much of my military service in a helicopter with a shabby 1 hour 25 minute endurance, fuel planning was always a major consideration.
Thread Starter
Joined: Sep 2011
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From: Lincolnshire
Ok guys, looks like I need to clarify a few things...! Have just spent the morning at the Club as it happens and as gusts of 40kts meant that flying was out, we have been chatting Navexes and Sector Recces (hmmm, i'm sure that one will get you all going too ) which we'll fly next time.
Broomstick - many thanks for your thoughts. I will certainly ask around at work as I know there is at least one Herc pilot. We also have ex-E3-D pilots on Station and a good friend of mine is ex-Vc10s so there are plenty of the Multi drivers around to ask! So in your opinion then, why are fuel management circles not good for legs of more than 50nm? I would ahev thought thaat, so long as all the figures were accurate, any length of leg was OK. The Grob is a twin seater with very little luggage space, so quite light really
Div fuel, this was one of the things I was discussing with my QFI today. The circles show planned fuel at all points. Div Fuel is red fuel and in our case we need to RTB with 18 litres FOG, 20 litres Div fuel (to get us easily to the other two local RAF airfields). Therefore the red fuel on the last point needs to be a minimum of 38 litres.
Peter, as other have said, these are indeed not range circles, but a quick and simple way of seeing roughly how much fuel you expect to have and therefore whether you need to divert.
As to the wind...well, asked my QFI that too and the answer was straightforward...its not an issue because you will even out fuel useage during the navex...ie on the southward leg we may have a tailwind...therefore use less fuel...so use more fuel on northward leg back home due to the headwind but we have more anyway because we used less than calculated because of the tailwind on the outward leg - seems logical to me! Groundspeed? I'll have to ask about that one!
Bad wx Divs? very true GW, we don't fly in bad wx..todays a case in point But true, we could end up in bad wx, thats where common sense and training come in. If I was solo, saw a massive great CuNim in my way I would see where I could divert to with the fuel I had, or decide maybe if its just one cell I could skirt round it..surely flying is all down to common sense, training and the pilot deciding the best course of action for a situation with div, fuel, wx all taken into consideration! Also, take Maorigh's point about ice...Last Weekend was a lovely winters day and we were flying...but were still concerned about ice!
Well, better get on with my navex planning with fuel circles to Wyton
GQ
) which we'll fly next time.Broomstick - many thanks for your thoughts. I will certainly ask around at work as I know there is at least one Herc pilot. We also have ex-E3-D pilots on Station and a good friend of mine is ex-Vc10s so there are plenty of the Multi drivers around to ask! So in your opinion then, why are fuel management circles not good for legs of more than 50nm? I would ahev thought thaat, so long as all the figures were accurate, any length of leg was OK. The Grob is a twin seater with very little luggage space, so quite light really
Even in a small aeroplane I allow for taxi fuel and I do calculate my fuel from destination to alternate (just in case the aircraft ahead of me does a wheels-up landing on the only runway at my destination). I plan each leg of a multi-stage trip as though each was a separate trip.
I don't have an issue with somebody doing fuel planning one way or another way, so long as it is realistic for the situation. (The "fuel circles" method is not good for "slow GA" because the wind is likely to be very significant, so the circles are not circles anyway).
pick up a tailwind on leg 1 you might then find your RTB fuel was no longer sufficient when you turn around to fight the headwind. I think we need to check back with GQ whether the fuel calculation allows for wind figures and Groundspeed?
Bad wx Divs? very true GW, we don't fly in bad wx..todays a case in point
But true, we could end up in bad wx, thats where common sense and training come in. If I was solo, saw a massive great CuNim in my way I would see where I could divert to with the fuel I had, or decide maybe if its just one cell I could skirt round it..surely flying is all down to common sense, training and the pilot deciding the best course of action for a situation with div, fuel, wx all taken into consideration! Also, take Maorigh's point about ice...Last Weekend was a lovely winters day and we were flying...but were still concerned about ice! Well, better get on with my navex planning with fuel circles to Wyton
GQ
Joined: Jan 2011
Posts: 660
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From: England
As to the wind...well, asked my QFI that too and the answer was straightforward...its not an issue because you will even out fuel useage during the navex...ie on the southward leg we may have a tailwind...therefore use less fuel...so use more fuel on northward leg back home due to the headwind but we have more anyway because we used less than calculated because of the tailwind on the outward leg - seems logical to me! Groundspeed? I'll have to ask about that one!
For example:
TAS 100 kts
Distance A – B 100 NM
40 kt headwind out
40 kt tailwind home.
IN STILL AIR CONDITIONS
Outbound time A-B is 100NM / 100 Kt = 1 hour.
Homebound time B-A is 100NM / 100 Kt = 1 hour.
Total time is 2 hours.
IN 40 KT WIND
Groundspeed out = 100 – 40 = 60 kts.
Outbound time A-B = 100Nm / 60 kts = 1.667 hours.
Groundspeed home = 100 + 40 = 140 kts
Homebound time B-A = 100Nm / 140 kts = 0.714 hours.
Total time = 1.667 + 0.714 = 2.381 hours.
Multiplying the extra 0.381 hours by 60 converts it into 22.88 minutes.
That’s an increase of 19% in flight time and fuel used.
Joined: May 1999
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From: Quite near 'An aerodrome somewhere in England'
As to the wind...well, asked my QFI that too and the answer was straightforward...its not an issue because you will even out fuel useage during the navex...ie on the southward leg we may have a tailwind...therefore use less fuel...so use more fuel on northward leg back home due to the headwind but we have more anyway because we used less than calculated because of the tailwind on the outward leg - seems logical to me! Groundspeed? I'll have to ask about that one!
Think of the extreme case of a 100 kt wind....
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The funny thing is that, on average, wind is always against you
Even a pure crosswind means you have further to fly.
I take the point about the "fuel circles". In that case, the figure inside the circle could be the endurance.
Even a pure crosswind means you have further to fly.
I take the point about the "fuel circles". In that case, the figure inside the circle could be the endurance.
Thread Starter
Joined: Sep 2011
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From: Lincolnshire
Fair enough, but who in GA actually flies in a wind of more than about 35kts? I certainly d0n't and wouldn't when qualified either!
PPruNe never ceases to amaze me...."Ask your instructor" they all shout...yet when I do...he's obviously wrong...... 
PPruNe never ceases to amaze me...."Ask your instructor" they all shout...yet when I do...he's obviously wrong......
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From: Niort
As I posted earlier, many people fly in 20 kts plus. At height that is frequently very much more - so there is every chance you will maybe inadvertently be flying in those winds.
As for covering the chart in chinagraph close to the turning points? Worst place to do it. These are the areas where you may need the detail. Best practice is to leave that entire area up to 10 miles or so completely clear - no lines nothing.
As for out and back equalling things up........... nicely put a little earlier.
Sector recce? All this pseudo 'top gun' stuff is all great fun I'm sure - but it does not seem to be a particularly good learning environment when fundementals such as an inaccurate guess about actual fuel consumption and ground speed are then detailed the the 'n'th degree.
As for covering the chart in chinagraph close to the turning points? Worst place to do it. These are the areas where you may need the detail. Best practice is to leave that entire area up to 10 miles or so completely clear - no lines nothing.
As for out and back equalling things up........... nicely put a little earlier.
Sector recce? All this pseudo 'top gun' stuff is all great fun I'm sure - but it does not seem to be a particularly good learning environment when fundementals such as an inaccurate guess about actual fuel consumption and ground speed are then detailed the the 'n'th degree.
Thread Starter
Joined: Sep 2011
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From: Lincolnshire
Sector recce? All this pseudo 'top gun' stuff is all great fun I'm sure -
....I haven't quite progressed to Carrier landings yet Seriously though, the terminology may sound bravado, and no, agreed, its not in the PPL syllabus. However.... I am particularly bad at knowing where I am in the local area, even after all this time. My usual response to the "Lookout" part of any cx is "err...thats the A1...Err..." But towns, orientation of our airfield etc etc, I am hopeless. Hence the reason for a need to fly an, ok, in more "normal" terms, a local area familiarisation trip...personally I prefer the more snappy "Sector Recce"!
I tried to insert a pic of my current navex to prove that the chart is still quite clear and understandable, but couldn't work out how!
...its not an "inaccurate guess", its worked out on fuel consumption and timing.
Joined: Jan 2011
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From: England
Grob Queen,
It was not my intention to "shout you down" but the idea that the tailwind will cancel out the effects of the headwind is potentially very dangerous. I have met many pilot who have clung to this mistaken belief right up to the start of their ATPL General Navigation studies.
My reason for providing my arguments in the form of a step-by-step calculation was to encourage you to try this for yourself. If you adopt this as a general principle you will probably find that you understand things much better. You might like to try it using the same scenario, but with a 35 kt wind. You will still find yourself about 17 minutes short of fuel. Can the aircraft that you fly, glide for 17 minutes from the altitudes at which you fly it?
If you now go back to your CFI and show him/her this thread, his/her reaction will probably be something along the lines of "but that isn't the question you asked me" or "I didn't say that", or possibly simply "Oh bugger, you caught me at a bad time, sorry".
It was not my intention to "shout you down" but the idea that the tailwind will cancel out the effects of the headwind is potentially very dangerous. I have met many pilot who have clung to this mistaken belief right up to the start of their ATPL General Navigation studies.
My reason for providing my arguments in the form of a step-by-step calculation was to encourage you to try this for yourself. If you adopt this as a general principle you will probably find that you understand things much better. You might like to try it using the same scenario, but with a 35 kt wind. You will still find yourself about 17 minutes short of fuel. Can the aircraft that you fly, glide for 17 minutes from the altitudes at which you fly it?
If you now go back to your CFI and show him/her this thread, his/her reaction will probably be something along the lines of "but that isn't the question you asked me" or "I didn't say that", or possibly simply "Oh bugger, you caught me at a bad time, sorry".
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From: Niort
Grob you've got two ears and one mouth.
Your fuel consumption is a guess because you have no direct measurement - you have an guess based upon whatever the usual use of the aircraft is.
Generally that will be circuits at a flying school. It sounds like your instrutors either have little understanding of flying cross country - or you have an interesting way of eliciting information - neither seem a good way of behaving.
Cross country the consumption can vary by well over 50% - flying rich - who knows - the numbers are not in the POH. How accurate are they?
Sector recce??? - if you can only fly yourself around areas you already 'know' then you are not navigating at all! Which will make fuel circles pretty much irrelevent.
Yes the terminolgy is full of bravado - why? It is far better to actually know what you are talking about.
Your fuel consumption is a guess because you have no direct measurement - you have an guess based upon whatever the usual use of the aircraft is.
Generally that will be circuits at a flying school. It sounds like your instrutors either have little understanding of flying cross country - or you have an interesting way of eliciting information - neither seem a good way of behaving.
Cross country the consumption can vary by well over 50% - flying rich - who knows - the numbers are not in the POH. How accurate are they?
Sector recce??? - if you can only fly yourself around areas you already 'know' then you are not navigating at all! Which will make fuel circles pretty much irrelevent.
Yes the terminolgy is full of bravado - why? It is far better to actually know what you are talking about.