by James Williams, FAA Safety Briefing

Of all the voltage regulators, in all the airplanes, in all the world, it balks in mine. It was the end of the long, first day in a two-day flight across the country involving three airplanes. It was at least hour eight, maybe hour 10, but the day had gone well — emphasis on had. As day faded into night, a problem entered the scene. The lighting (panel and exterior) started to fade in and out. Except for our lights, which continued to surge in and out like a cut-rate dance club, our systems seemed to work. Still, we started shedding electrical load as we continued and completed our approach to the night’s destination airport.

The next morning an Aviation Maintenance Technician (AMT) from the local FBO investigated our issue while we watched the other two airplanes in our group depart. Then we waited … and waited … and waited while the AMT diagnosed and replaced our faulty voltage regulator.

In the meantime, weather had become a challenge. Through an extensive in-person briefing with the Flight Service Station that happened to be on the field, we found a window, but it meant another delay. It was early afternoon before we were rolling down the runway at Louisville.

The ride was a bit rough, but we made it through a gap in the line of storms and arrived at our northern Georgia fuel stop six hours behind our planned schedule. After refueling ourselves along with the airplane, we launched for a long last leg to Florida that worked, at least on paper.

By the time we were off the coast of Jacksonville, conditions didn’t appear to be as favorable as the earlier forecast had predicted. Meanwhile, our fuel situation was getting tighter. At this point, though, we were close to home … so we decided it would be okay — but we would do the visual approach to save fuel.

If you think we were compromising safety due to a fuel condition, you’re right. With our fuel gauges showing less than ten gallons per side, we touched down at home. Out of curiosity (probably the morbid kind), I decided to take a quick look in the fuel tanks. I saw bare metal. My best guess is that we had a bit more than 30 minutes’ worth of fuel, but the visual picture of what landing looked like with no more than the legally-required reserve fuel, sent a chill down my spine.

Little Things Make a Big Difference

It was not an easy day to forget. I’ll always have Louisville as a reminder of how easy it can be for a good pilot to rationalize a bad decision. Louisville also gave me a vivid lesson in the much-discussed chain of events, because it was not just any single thing, but rather an accumulation of small things that put conservative strategy into the red. Delays exacerbated our existing fatigue. We had a strong case of get-home-itis. The last leg was right on the line in terms of range. It was all legal, but it left little margin for error.

I’m not alone in my dance with the fuel management devil. The latest Nall Report attributes 76 accidents to fuel management in 2014. Of these, seven were fatal. Almost two thirds arose from poor preflight planning.

Personal experience is both a costly and inefficient way to reduce these accidents. So what can we do about it?

It Starts with Thinking

Since two thirds of these accidents arise during preflight, let’s start there. Looking at my own errors, I was too aggressive on range estimates. It worked on paper, but it left me with few options for “what if” situations. A good set of personal minimums would have helped.

In hindsight, I could have used percentage-based fuel usage limits along with legal reserve requirements. Here’s how that works. You might set a threshold for further analysis at the point where you’ve used 70-percent of total fuel with an upper “redline” limit of 80-percent. The percentage framework is easily portable from airplane to airplane, regardless of the number or size of fuel tanks. It also is more consistent with longer-range aircraft, where a straight minute-based reserve is less strict. Best of all, it gives you a simple and practical way to factor more than just the legal reserve into your planning. A flight that only projects a 30-percent fuel burn probably doesn’t need as much examination as a flight that requires 80-percent of your fuel supply. But having a standard makes you actively consider it.

Another fuel management suggestion is to calculate flying time under several wind conditions. Then set baselines that allow you to see how a change in conditions will shift your planning from sensible to marginal. Failing to do that was one of my mistakes. If I had realized just how much of a difference a 10-knot wind change made to my progress, I would have reconsidered. Figuring this out at 8,000 feet, two thirds of the way through the flight, was far less useful.

One fuel management suggestion is to calculate flying time under several wind conditions. Then set baselines that allow you to see how a change in conditions will shift your planning from sensible to marginal.

Hardware Fixes

The simplest hardware fix is a timer, which the Nall report characterizes as probably the single most effective tool for preventing fuel management accidents. Today’s gadgets and apps are glitzier than the timer, but it is a simple tool that still has plenty of value — and you can easily transfer it from one airplane to another.

You can use it in several ways. The most obvious is to use a timer to track overall flight time. You might also build timer use into your personal procedures, letting it serve as a catalyst: Every X minutes, check destination weather. Every Y minutes, check ETA against original planning.

These discrete decision points can help you identify trends you might otherwise miss. For instance, on your last check, your arrival time was 10 minutes later than expected. This time, it’s 15 minutes later. This trend tells you to start watching that metric more closely, and take action if it creates a problem. The same applies for weather. Humans tend to be very bad at detecting gradual change. Creating discrete data points makes this easier for our brains.

A more sophisticated (but also more costly) solution is the advice I got from a friend: “If you have an airplane, get a good fuel totalizer.” Knowing exactly how much fuel you have onboard is a huge advantage. Totalizers remove (or correct) the assumptions made in flight planning. We may plan for ten gallons per hour of fuel consumption but actually burn less than nine. Knowing whether I have an extra three to four gallons on board might change my thinking. The same is true — but more critical — in reverse.

Rigging the Game

Sometimes we like to think life evolves as the spin of a roulette wheel, where the ball can land anywhere. But as Casablanca’s Rick Blaine demonstrated in the casino section of his establishment, you can make good things happen by making it land exactly where you want it. So build a system of habits, techniques, and tools that maximize your chances of winning the fuel management game every time, every flight.

Learn More

• Pilot’s Handbook of Aeronautical Knowledge Chapter 16
• AOPA Air Safety Institute’s 26th Joseph T. Nall Report

James Williams is FAA Safety Briefing’s associate editor and photo editor. He is also a pilot and ground instructor.