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How low do you go(fuel)?

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PilotjohnS

Well Known Member
Must curious how low everyone goes on there fuel in each tanks.

Do y’all try and land with less than 3 gal per side, or maybe not less than 5 gals per side?

Thanks
 
Five gallons per side is about as low as I'm comfortable with, especially given the accuracy of the fuel senders.

My aircraft has wingtip tanks (total capacity of 48 gal), so I haven't really had to stretch at all when it comes to gas. My posterior will wear out before the fuel does.

--Ron
 
My fuel cube is really accurate, like within two tenths of a gallon.. that being said, I’ll run a tank dry, then switch to the good tank. I would rather have 6 gallons in one track than 3 gallons each spread among two tanks.
I have a great way I manage my fuel so I know almost to the minute that it runs dry and often I can switch tanks when the fuel pressure starts to fluctuate and the engine won’t even miss a beat. Instead of changing tanks at an interval of time (30 minutes), I’ll switch tanks after 5 gallons or some whole number. This way I know exactly how much is remaining in each tank. For example, my RV-4 has 16 gallons per side, 32 total. I’ll start on one tank, switch after my totalizer says 27 remaining, then I’ll burn 16 out of the other tank (totalizer says 11 remaining) and I know there’s 11 remaining in that first tank (16 minus the first 5). The dangers are if you develop a leak, feeding problem, or vent issue. I only do this when I have to max out range. My longest flight was 4:20 and 638 nautical miles and landed with 5 gallons reserve! And that’s with a small tank 32 gallon RV-4!
 
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10-gallons is my normal low.

IF on a long cross country, I am ok with letting one tank get as low as 5-gallons when I am 100% certain that airport I am aiming for has gas and the pump is working. (Done that twice in 25+ years.) When the fuel totalizer says that I have 10-gallons left, I will run one tank dry before switching to the other to land.
 
My bladder is the main determiner of when I refuel. That said...my red cube and Advanced Flight fuel computer are extremely accurate combination and I'm confident in it down to 3 gallons per side. I also stick the tanks before each flight.
 
Taltruda said:
My fuel cube is really accurate, like within two tenths of a gallon.. that being said, I’ll run a tank dry, then switch to the good tank. I would rather have 6 gallons in one track than 3 gallons each spread among two tanks.
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Same here with my gauges, not so much the redcube though, for reasons I still don't understand, it fluctuates in flight.

Nonetheless, I takeoff & climb on the left (Avgas) tank, swap sides (Mogas in the R), run that dry (~2H40M) , swap back and know every last drop of usable fuel is in the selected tank.

18L is the lowest flight planned fuel on landing I'll accept. 15L is my lowest actual so far, returning home in CAVU conditions, all in the left tank. Usually, I'll want an 25L / 1 hour if the weather's a bit sketchy.
 
RV6_flyer said:
10-gallons is my normal low.

IF on a long cross country, I am ok with letting one tank get as low as 5-gallons when I am 100% certain that airport I am aiming for has gas and the pump is working.
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Once when my wife and I were flying a long XC with a planned fuel stop, we landed at our refueling airport. Right after the usual dash to the restroom, there was an unplanned power outage.

So here we were, part way into a 700+ km trip, at a strange airport with fuel but no power to run the pumps. I made the decision to fly to another airport nearby and hope that they had power and fuel. Lucky for us they did, but an important lesson was learned about fuel-stop planning.

-Marc
 
Taltruda said:
I’ll run a tank dry, then switch to the good tank. I would rather have 6 gallons in one track than 3 gallons each spread among two tanks.
Click to expand...

This is the way I do it. I would rather run one tank nearly dry while in level cruise, leaving a good quantity in the other tank for descent and landing, to make sure it doesn't get unported in a turn.
 
I always carry way too much fuel, and try to land with 1 hour or more of fuel. To me, it's not worth the risk, even if I know the airport I'm landing at is good VFR and has fuel. It justs takes one airplane ahead of me with a flat tire to foul the runway.

Vic
 
I got down to about 13 gallons once and I was very uncomfortable. Mainly because of where I was flying. I stupidly didn't start with full tanks.

HB-YMM - Glenforsa-EGCK - 20220829.png
 
vic syracuse said:
I always carry way too much fuel, and try to land with 1 hour or more of fuel. To me, it's not worth the risk, even if I know the airport I'm landing at is good VFR and has fuel. It justs takes one airplane ahead of me with a flat tire to foul the runway.

Vic
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Yup - an hour of fuel is my usual minimum as well (except for the jet….). And remember that if you’re depending on your super-accurate red cube to tell you when to get gas, I am betting you only have one of them. And you won’t know that it has gotten stuck or inaccurate until you fuel after it fails….)

Always conservative with fuel!
 
jcarne said:
About 5 gal a side is my min. Leaves a bit over an hour of reserve.
Click to expand...

Same for me, but for an additional reason: base-to-final slips. When slipping the aircraft in the base-to-final turn (depleting excess airspeed or altitude), the bottom-wing tank’s fuel runs downhill away from the fuel pickup. I religiously select the top-wing tank before landing (not necessarily the fuller tank). For example, if it’s left traffic, I’ll feed the right tank.

However, if I missed that step and left the bottom wing’s tank selected, 5 gals ensures there will still be fuel available even if I have to stand on top rudder in the slip to final.

My technique. Use with care and your own due diligence.
 
Run one tank dry leaves the ?? know amount in the remaining.
I have always liked fuel left in the tank when I land cause I've landed and there was no fuel where it was supposed to be.
Alternates are good only if you can get there.
My luck varies Art
 
Ironflight said:
Yup - an hour of fuel is my usual minimum as well (except for the jet….). And remember that if you’re depending on your super-accurate red cube to tell you when to get gas, I am betting you only have one of them. And you won’t know that it has gotten stuck or inaccurate until you fuel after it fails….)

Always conservative with fuel!
Click to expand...

Are there people that rely solely on their red cube to tell them when to get gas? That certainly does seem unwise.
 
As the old saying goes.........

vic syracuse said:
I always carry way too much fuel, and try to land with 1 hour or more of fuel. To me, it's not worth the risk, even if I know the airport I'm landing at is good VFR and has fuel. It justs takes one airplane ahead of me with a flat tire to foul the runway.
Vic
Click to expand...

"The only time you can have too much fuel is when you're on fire."
 
Reserves

Interesting replies.
One hour reserves seems good. Enough to get to another airport with fuel.

Some of the best laid plans of mice and men often go astray-John Steinbeck
 
My minimum is one hour. I start getting uneasy at 1.5 hours. I have experienced inaccurate weather forecasts a number of times in 44 years of flying. I rarely takeoff without full fuel in the 7 unless I’ve planned aerobatics or am staying local to the airport. Many years ago I was flying a 172 to Denver. Even stopped at Lamar to check weather. There was a developing thunderstorm behind the mountains which blocked the radar. It became very turbulent with 2000 rpm downdrafts. I tried calling FSS while airborne but couldn’t reach them. I was having trouble keeping control. Diverted SW looking for the first suitable airport. This was in the very early days of gps. Cutting to the chase, we landed at Colorado Springs East in winds gusting to 55 knots. I had 6 gallons left in the tanks. When I tried to turn onto the taxiway the wind would weather vane us back into the wind. So we sat for awhile pointing into the wind until the gusts subsided a bit. I called FSS from the land line. They were very concerned about us. A bonanza inbound to Arapahoe (Centennial) had the leading edges flattened to the spar by hail. One of only two times in my flying life that FSS apologized to me foe the forecast WX.
 
I get real nervous if less than an hour remaining.
On one of my trips to OSH, I landed at my normal refueling stop, and no gas was available. (late Sunday afternoon)
Went to another airport a short distance away, and the pump was broken.
Okay, now I'm getting nervous!
Finally found gas, but was glad I didn't run to a level where I HAD to get gas at the first (or second) stop.

Another time, the cheap gas airport had nice paved runway aligned with the fairly stiff wind, only to find out on first call that that runway was closed. Uh oh... Now I had a stiff x-wind to deal with that I was not mentally prepared for. Got it down, but another reason to have enough reserve for a distant alternate.

I also never run a tank all the way empty. I always leave at least five in it.
 
MacCool said:
Are there people that rely solely on their red cube to tell them when to get gas? That certainly does seem unwise.
Click to expand...

My totalizer has proven really accurate and reliable, (I don’t have the red one, I have the ft42 I think it’s called) but I also reference my gauges, which are reliable at the lower scale. Along with known fuel burns, verified by a timer and actually running one tank dry, I’ve grown to trust my system. When my totalizer says I have 0.1 remaining in the selected tank, I keep my hand on the selector valve, and at 0.0, my fuel pressure starts varying, fuel flow drops off, I switch tanks and hit the pump. Because the tank went dry at a predictable time, it verifies my totalizer is working correctly. True, it could fail after then, but I now know exactly how much fuel is remaining and where it is. Even if the totalizer completely blanks out, I have known burn rates (as long as I don’t change anything) and a known quantity on board.
 
To the OP’s original question, 10 gal reserve is where I draw the line. Although I don’t think I’ve ever actually landed with less than 15 or so - bladder limited. In the -10, that’s 1 hour flying LOP. I use the fuel totalizer for this. The tank floats, calibrated thru the efis, are very accurate near the low end, and typically are within 2 gal of the totalizer. I have never run a tank dry, but if someday I screw up and need every drop I will. If I can get the destination wx and there’s a decent crosswind I’ll try to leave the majority of the gas in what will be the raised wing on landing.
 
Taltruda said:
My totalizer has proven really accurate and reliable, (I don’t have the red one, I have the ft42 I think it’s called) but I also reference my gauges, which are reliable at the lower scale. Along with known fuel burns, verified by a timer and actually running one tank dry, I’ve grown to trust my system. When my totalizer says I have 0.1 remaining in the selected tank, I keep my hand on the selector valve, and at 0.0, my fuel pressure starts varying, fuel flow drops off, I switch tanks and hit the pump. Because the tank went dry at a predictable time, it verifies my totalizer is working correctly. True, it could fail after then, but I now know exactly how much fuel is remaining and where it is. Even if the totalizer completely blanks out, I have known burn rates (as long as I don’t change anything) and a known quantity on board.
Click to expand...

I have always had a very accurate FF. This winter I had a mechanical pump go bad and was dumping fuel out the by-pass. My FF was perfect for fuel burn but did not calculate the fuel I was dumping overboard.
I will only trust that fuel burn so far now days.

If I am headed to my home airport I will get as low as one tank close to dry as long as I know I have about 5 gal in the other tank. Like some, at this point I have my hand on the valve and switch just before landing.
Long flights I prefer at least an hour.
 
I have totalizer and gages, five gallons which is over half an hour. I have run the tanks dry and I actually have 16 gallon of useable in each tank (level flight) I try not to ever put more than 25 gallons in at fillup.
 
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My RV6 holds 38 gallons. When the fuel pumps asks for max $$ or gallons, I always say 30 gallons, and it has never stopped on it's own.
 
scrollF4 said:
Same for me, but for an additional reason: base-to-final slips. When slipping the aircraft in the base-to-final turn (depleting excess airspeed or altitude), the bottom-wing tank’s fuel runs downhill away from the fuel pickup. I religiously select the top-wing tank before landing (not necessarily the fuller tank). For example, if it’s left traffic, I’ll feed the right tank.

However, if I missed that step and left the bottom wing’s tank selected, 5 gals ensures there will still be fuel available even if I have to stand on top rudder in the slip to final.

My technique. Use with care and your own due diligence.
Click to expand...

Not a bad idea for some added safety. However, personally; if I'm in a slip I definitely got the field made. Still not a bad idea in case you need to go-around though.
 
Taltruda said:
My totalizer has proven really accurate and reliable, (I don’t have the red one, I have the ft42 I think it’s called) but I also reference my gauges, which are reliable at the lower scale. Along with known fuel burns, verified by a timer and actually running one tank dry, I’ve grown to trust my system. When my totalizer says I have 0.1 remaining in the selected tank, I keep my hand on the selector valve, and at 0.0, my fuel pressure starts varying, fuel flow drops off, I switch tanks and hit the pump. Because the tank went dry at a predictable time, it verifies my totalizer is working correctly. True, it could fail after then, but I now know exactly how much fuel is remaining and where it is. Even if the totalizer completely blanks out, I have known burn rates (as long as I don’t change anything) and a known quantity on board.
Click to expand...

Of course. Fuel computer, gauges, always stick the tanks as routine part of the pre-flight, and appropriate mission planning with known fuel burn. Hard to believe anyone would take off only relying on one of those parameters for something as critical as as fuel on board.
 
Mile High Relic said:
My RV6 holds 38 gallons. When the fuel pumps asks for max $$ or gallons, I always say 30 gallons, and it has never stopped on its own.
Click to expand...

38, but 36 or 37, maybe, useable. You might have a bit less than you think, but your strategy has legal reserves. Just don’t want folks thinking a 6 has 38 usable gallons a fuel.

My totalizer is configured for 36. My fuel warnings occur at 5 gal in a tank or 10 total. I follow what most have posted here and am landing with at least an hour reserve. Plenty of range for my legs and bladder.
 
jcarne said:
Not a bad idea for some added safety. However, personally; if I'm in a slip I definitely got the field made. Still not a bad idea in case you need to go-around though.
Click to expand...

Jereme,
I concur. Frankly, I consider a final turn slip punishment for bringing it in too tight, too fast, not enough crosswind correction on downwind, yada yada. Still, a good skill to have (but handle the tanks correctly).
 
Same

airguy said:
This is the way I do it. I would rather run one tank nearly dry while in level cruise, leaving a good quantity in the other tank for descent and landing, to make sure it doesn't get unported in a turn.
Click to expand...

Same here. Though, I always plan for >10 gallons on landing. I also check the accuracy of my gauges with what-is-shown before and after fueling. I find my gauges to be consistently spot-on.
 
Pilot know thyself… and your aircraft

swjohnsey said:
I have totalizer and gages, five gallons which is over half an hour.
Click to expand...

+1 for me. Normally 1 hour reserve is my practice however in the RV on true cross the country flights I will stretch the range. I’ve spent a lot of time verifying the accuracy of the FF and fuel gauges. (AF5600 allows calibration of fuel quality in both 3 point and level. The Dynon HDX I put in my C180 is level flight only). As has been pointed out you can lose fuel out of the tank by various means so you need to closely monitor the FF and gauges agree on quality remaining.
 
But what if...

A one hour reserve works IF... the card reader isn't broken; or the hose reel isn't stuck; or they only sell gas on weekdays. I've encountered all of those.

My strategy is to land with two hours of gas. If gas turns out to be unavailable, I can go somewhere else farther along and land with an hour reserves. Been glad I did this three times now, off in the sticks...
 
Wing nut said:
+1 for me. Normally 1 hour reserve is my practice however in the RV on true cross the country flights I will stretch the range. I’ve spent a lot of time verifying the accuracy of the FF and fuel gauges. (AF5600 allows calibration of fuel quality in both 3 point and level. The Dynon HDX I put in my C180 is level flight only). As has been pointed out you can lose fuel out of the tank by various means so you need to closely monitor the FF and gauges agree on quality remaining.
Click to expand...

I've had a leaking sump drain before. Fuel gage saved my donkey.
 
Someone earlier said their bladder controls landing fuel. For flight planning purposes this gives me two hour legs - maybe two and a half. Given that limitation, I generally land when my totalizer indicates between 20 to 15 gallons. The left and right fuel indicators are pretty accurate below 12 gallons per tank. I definitely trust the totalizer because it’s always within one gallon when I fuel back up.

Besides, this is definitely a safety issue because it’s hard to see the runway through the yellow fog buildup! 😁
 
Letting your fuel reserve go too low, whatever the reason, will make an impression. In my case it was trying to get home at midnight, fighting a strong headwind, not wanting to stop for fuel in the dead of winter, then finding the lights at my home field would not turn on. Pushing low fuel isn't worth it.
 
KRviator said:
Same here with my gauges, not so much the redcube though, for reasons I still don't understand, it fluctuates in flight.
Click to expand...

Is your engine carbed or injected? Mine is carbureted and it fluctuates at lower power settings with boost pump off. At high power settings or with boost pump on it's pretty constant (+/- 0.1 GPM).

I'm wondering on the MA-4SPA carb float requires some pressure for the needle valve to come off the seat, so the bowl level needs to drop enough to permit full flow. In theory, I think the combination of flow and pressure would keep the float at an intermediate possession always allowing fuel flow into the bowl, but maybe under certain circumstances it cuts off flow. There seems to bee a corresponding fuel pressure fluctuation with mine also.

On topic...one of things the US has going for it is there's airports with fuel nearly everywhere. Not so much in Oz
 
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My $0.02

I'm pretty paranoid about fuel exhaustion. One hour remaining is my absolute limit. At cruise, I typically burn ~10 gph, but frankly prefer to land with 15 gallons or more showing on the computer.

The -10 holds 60 gallons. I program the fuel computer as "full" at 58 gallons, to overcompensate a bit for any unusable fuel or not getting a tank absolutely full. I don't trust the gauges--I've gotten "Low Fuel X tank" messages, which are programmed to alert at 6 gallons remaining, more than once when they aren't really that low. The fuel computer is pretty well calibrated. If it says I'm going to need 20 gallons, I may only be able to put in 19.5 or so, but that's about as "off" as it gets, and if it's off, it's always overestimated what I could actually put in.

Yes, there could be a leaking strainer, but I check those very well during pre-flight to be sure that neither continues to drip after sumping tanks. Unlike high wing A/C, we can see our fuel caps, so if there's a leak there we should know it early.

On my kneeboard sheets, I have places for amount remaining at the end of a flight, amount expected to fill, and amount purchased. I've compared amounts expected with the amount purchased at every fill-up for the 5+ years that I've owned the plane.

In part because I don't trust the individual tank gauges, on long X-Cs where I anticipate the possibility of nearing minimum fuel, I also print out a small Excel table to track burn from each tank. That way I know (again, absent an undetectable leak) exactly how much is in each tank. Column headers are: Tank, Time (of tank change), Total Remaining, Used (Leg), Remaining (L) and Remaining (R). With full tanks, I usually depart on the left, switch after burning 10 gal, then switch again after burning 20 gal from the right. If I'm going to go below 5 gallons in the left tank, I'll switch one last time. That keeps me within the recommended max fuel imbalance of 10 gallons.
 
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