Running On That Last Gallon of Fuel

[Bill Greenwood]

Author Richard Collins, ( I think) wrote there were 2 dumb things no pilot should ever do, run out of fuel or fly into dangerous weather, and of course doing both together is double nuts.
Another idea is that an accident it often a chain of events that lead to it. I came within a couple of gallons of running out and there were half dozen or more factors.

First, I had been flying my '77 Mooney 201 and you fill it up with 64 gal and its burns 10 in cruise so fuel is really not a consideration, you get spoiled. When I switched to my "55 Beech T-34 everything about fuel became tighter. It holds only 50 gal, burns about 13 leaned out in cruise and at 140k is 10 -15knots slower than the Mooney. The endurance is bout half the Mooney. Next, I fill up the tanks after I fly and I did so this time, but I was taking the plane to Front Range Airport for its annual. Over the time of the annual they ran it on the ground a bit and so when I went to fly it was not quite full, maybe 46 gal and I didn't top it to the brim. This was a new shop and proved to be very negative and antagonistic about the plane so I picked it up to take to Parks in Texas. I was planning on stopping at Tom Danaher's private strip near Denton. Tom was a long time CAF member and had the last victory in WWII flying a Corsair. So I set out and would normally fly 13,500 leaned out to 13 gph. An overcast made me fly lower, under 10,000 and gs was less and fuel burn may have been higher. It was a new route and I was looking at the map and as I neared OK City I was talking to military approach control, got preoccupied with them and traffic and not focused on fuel. One gauge was not quite accurate, then I ran an tank dry and it quit. I had a freeway ahead and the airport coming up so I glided down and landed, and switched tanks as I made the approach. The engine was running in order to taxi in but not much on the gauges. I refueled and found I had only a few gallons in one tank and the other empty. It made a big impression on me.
I'm like the pilot who says when he taxis in he wants to hear that reserve fuel sloshing in the tanks!

[Bill Greenwood]

Most of my flying now is in my Bonanza which holds 108 gal and burns about 18 gph leaned out in cruise at 170K and twice that at full throttle climb. About 3 hour legs are what I normally plan to fly. The extra fuel is there also if needed.

[ahramin]

Personally, I think most of these incidents stem from fuel planning that consists of "I always fly full tanks".

The other day our fuel pumps were down and an RV owner was dissapointed not to be able to go flying because he couldn't fill his tanks. He had half full tanks and only wanted to go flying for an hour. He would happily fly 3.5 hours with 4 hours of fuel on board, but wouldn't fly 1 hour with 2 hours of fuel on board.

I've been training an RV-6 owner to fly IFR and he had trouble understanding why we needed to know our planned fuel burn down to the gallon since we had way more fuel than we needed. Simple answer is someday you may not and on that day some experience in fuel calculations will come in handy.

I currently have my BD-4 for sale and I often am asked what's the useful load with full fuel? I don't see how that's going to tell the buyer anything useful unless they have a need for 750 nm legs and can go 6 hours without a break. With passengers on board my legs are ideally 2 hours - maximum 3 - so when evaluating the usefulness of a plane I want to know what the useful load is with 4 hours of fuel.

Our RAA club recently built a Zenith 750 Cruzer and with 2 adult males and no bags, cannot carry full fuel. This was seen as a huge problem until we did a bit of math and found that we could carry 20 pounds of bags and 3 hours of fuel and our normal flights are under one hour.

So I recommend recreational pilots view fuel the same way airlines view fuel. Know how much you need and know how much you have. Buy or make a calibrated dip stick. Determine your fuel burn as exactly as you can. Before every flight, write down how much fuel you need on board and how much you think you are going to use. Dip the tanks before and after every flight and compare to your preflight calculations. Keep track of every gallon that gets put in the tank and compare that to your dip stick measurements. I think any pilot who does that for 6 months will find that they can fuel plan within a gallon on any given flight, and will be much less likely to run out of fuel.

[robert l]

I have been renting a Cessna 172 and recently have a 150 availabe, at 30 bucks an hr less that the 172 I can stand some lack of comfort. At the moment, I'm about 50 lbs beyond the standard 170 lb pilot. Flying solo presents no problem but if I wanted to take another person I need to know how much fuel is in the tank so I don't go over gross wt. The plane is not always topped off after each flight so it's generally not a problem whether there is a passenger or not. I'm just flying for fun so I can adjust my flying time accordingly and to be on the safe side, I always check my fuel at each stop. It's just good practice.
Bob