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Running on emptyRunning on empty

The recent death of a 21-year-old Georgia student after an apparent case of fuel exhaustion is a reminder that even the most controlled of all flight environments is not immune to the most avoidable of all aviation accidents. If there’s no good reason for any pilot to allow a perfectly good aircraft to run out of fuel—and there isn’t—there’s even less excuse for an instructor to allow that to happen on a dual lesson, or for a school to permit a student to depart on a solo flight without ample (even bountiful!) reserves.

We can take some comfort in the fact that fuel mismanagement occurs less often on training flights. During the 10 years covered by the AOPA Air Safety Institute’s analysis of Accidents During Flight Instruction, fuel mismanagement contributed to 3.9 percent of all fixed-wing instructional accidents compared to 8.6 percent on noninstructional flights. Since the total instructional accident rate was also 10 percent lower, this translates to a 60-percent reduction in the average number of episodes per 100,000 hours flown. That’s good, but hardly sufficient. Failures to manage their fuel supplies during training flights brought down 74 airplanes over the course of that decade, nearly two-thirds of them (48) during dual lessons. Helicopters fared better, sustaining just 11 fuel-mismanagement accidents in the same period; these made up just 2.7 percent of all instructional accidents in helicopters. The ability to make precautionary landings nearly anywhere is probably not the only factor in that difference.

Eleven cases aren’t enough to support much analysis. For the record, four were complete fuel exhaustion; four more were ascribed to the pilots’ failure to use carburetor heat; two to attempts to lean the fuel mixture; and one to a failure to switch tanks. Only two occurred on student solos.

The fixed-wing side, however, reveals some interesting patterns. Outright fuel exhaustion accounted for two-thirds of the accidents on student solos—not so surprising in light of the fact that less than 20 percent of the airplanes involved were models that required their pilots to change tanks. However, almost half those during primary dual instruction were the result of fuel starvation in airplanes that can only feed from one tank at a time; the instructors were cited for failing to assure the tanks were switched when needed. Given that students generally solo the same models in which they take their dual, this raises the disquieting possibility that students flying alone have actually done a better job than their CFIs of remembering to change tanks on time.

Starvation accounted for more than 70 percent of all fuel mismanagement accidents in advanced instruction, including four—three of them in twins—in which fuel selectors were set to the Off position in flight. This reflects not only the characteristically greater complexity of the airplanes used for advanced training (more than half were either twins or complex singles, and only four of these accidents involved models whose fuel selectors could be set to Both) but perhaps also better flight-planning and monitoring skills among more experienced pilots.

Still, in nearly 30 percent, inadequate planning or a lack of attention to fuel consumption during the flight resulted in exhaustion. Failures to make timely tank changes remained the most common mistake, however, accounting for nearly half of all fuel mismanagement during advanced dual instruction. Inappropriate use of boost pumps caused two accidents, and one was attributed to water contamination that should have been detected on preflight.

Compared to the total of more than 2,400 instructional accidents that took place in the same period, the 85 caused by inattention to fuel supplies might not sound so bad—until you realize that utterly preventable oversights wrecked an average of one aircraft every six weeks. The details suggest the prevention strategies. Students seem to do a pretty good job of remembering to change tanks if needed (perhaps aided by electronic timers or alarms), but CFIs risk getting too absorbed in the lesson to remember to tend to the aircraft. Students could benefit from closer scrutiny of their flight planning and clear direction about the advisability of taking on fuel during cross-countries, especially if they’ve gotten lost. And as we’ve suggested before, unless weight will be an issue for a subsequent lesson, there’s no real advantage to sending any student off with tanks that are less than full.

David Jack Kenny is manager of safety analysis for the AOPA Air Safety Institute.

ASI Staff

David Jack Kenny

David Jack Kenny is a freelance aviation writer.

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