The saying goes that “you can never have too much fuel unless it’s on fire.” I have always been a believer in that truism, so I always fill the tanks before I go anywhere… except on a recent trip, which just confirmed the wisdom of whomever came up with the old chestnut.
I was flying DCU-IGX, which I flight planned as 394nm, just under 3:00 of flying time, and about 48 gallons of fuel. Sure enough, when I arrived, I’d drained one main tank, one tip tank, and about half of the other tip tank. The CGR-30p engine monitor, my analog gauges, and my eyeball inspection all agreed.
Fuel at IGX was $5.28/gallon. Fuel at my home airport is $4.80/gallon. “Hey,” I thought. “I have enough fuel to get home if I just fill the tip— that will give me 59gal on board, which still gives me a VFR reserve.” Visions of dollar signs dancing in my head, I filled out the fuel ticket and went into town to lift all the weights with Alex. When I returned, I verified the fill, sumped the tanks, and headed to the departure end of the runway with 59 gal on board.
Once airborne, the problems started. ATC wanted to vector me well north of where I wanted to go because of weather, and to keep me out of the RDU arrival corridor. They also gave me a higher altitude, so I burned more fuel in the climb than I’d expected. Once I got past the first waypoint, I had to divert around more weather… see where this is going? About 40 minutes into the flight it became clear that I didn’t have enough fuel to get home without a stop.
I’m not talking “had enough fuel if I ate into my reserve,” I’m talking “engine monitor shows negative fuel remaining on landing.” Noooope.
A little head scratching ensued, and I determined that I had plenty of fuel to make Winchester, where fuel is only $4.09/gallon. When I landed, I took on 71 gallons out of the 82-gallon usable capacity— within my 45-min reserve requirement, but just barely.
Lesson learned: by not filling that tank in Chapel Hill, I saved (25 gal * $0.48/gal)… a whopping $12. Then I cost myself another 30-40 minutes of diverting to Winchester, landing, fueling, and returning home. In this specific case, I was lucky because Winchester is open 24/7 and is easy to get into and out of, and their fuel is cheap. I probably netted a few dollars of savings filling up there as opposed to filling all 4 tanks in Decatur— but that unpleasant feeling of not having enough fuel aboard is one I don’t care to repeat.
Fill ‘er up!
Paul's Down-Home Page 
I’m a big believer if, as a pilot, I’m going to cry over fuel that cost $20 more at one airport then I shouldn’t be flying. I’ve had pilot tell me, “you should just fly to XYZ to get fuel because it’s cheaper.” Even if it’s on my way, I will have to descend, get in the traffic pattern, land, time spent on the ground fueling, and climb back up to altitude. Time is worth something (at least mine is to myself!). The knowledge that I have a full tank of gas makes me feel good also!
Lesson learned!
Right on. Normally I will fill the tanks before departure to avoid having an en route stop just to save $20. I’m also happy to pay a little more to go into a field that has a nice long runway and a working bathroom!