A CFI giving primary dual instruction is generally presumed to be acting as pilot in command, and is consequently held responsible if anything goes wrong. Sometimes this can seem a little unfair, as when a low-time fixed-wing student bounces a landing hard enough to damage the gear or wrinkle the firewall. The line between giving the student latitude to learn and intervening in time to save the aircraft can get pretty fine. On the other hand, when difficulties arise from basic failures in flight planning—getting caught above an expected layer of evening fog, for example, or neglecting to assess takeoff or landing performance—the instructor’s culpability is hard to deny. In our book, the most glaring examples of flight instructors shirking their “responsibility for … the operation of that aircraft” (in the immortal words of FAR 91.3) are dual flights that come up short because their CFIs allowed the aircraft to succumb to fuel exhaustion.
It’s hard to think of any flight-planning task more basic than making sure there’s enough juice on board to keep the engine running from takeoff to touchdown (not to mention the required reserves). The essential elements aren’t all that complicated: One needs to know the expected length of the flight, fuel burn under those conditions, and the quantity already in the tanks. Maybe we’re idealists, but these are all bits of information we’d think any pilot would want before attempting aviation. Of course, knowledge is only as useful as the decisions based on it, so a fourth piece is also crucial: willingness to take action when things aren’t adding up.
Human nature being what it is, not everyone who’s committed this sin is eager to own up. A few years ago, Flight Training published an account of a fuel-exhaustion accident on a dual flight in a Cessna 172. On their way home from doing touch-and-goes at another airport 14 miles away the engine quit, necessitating a forced landing. It turned out the instructor hadn’t verified the student’s preflight estimate that each tank held about six gallons. After the story ran, however, the editors received an angry e-mail from the CFI involved insisting that the loss of power must have been due to some sort of mechanical problem. The fact that the FAA inspector who responded to the scene found no discrepancies with the engine or fuel system, no sign of leakage, and no usable fuel in the tanks, lines, or strainer might not prove he was wrong, but certainly doesn’t convince us he was right.
Except when weight and balance require, there’s no obvious advantage to taking off with low fuel. If refueling after every lesson seems a little extreme, at least consider setting firm rules on when it’s absolutely required. Say, for example, a trainer has five hours of endurance. If the hours flown since the last fill-up and those expected on the next lesson sum to more than three, it’s time to get some gas.
Fuel requirements are more delicate in most small training helicopters thanks to sharp limits on maximum takeoff weight; the trade-off is that they have far more options for precautionary landings if supplies start to run low. Of course, the best place to make a precautionary landing is probably still at an airport, so we’re left shaking our heads at accounts of helicopter pilots who pass up available fuel stops only to have to put it down out in the countryside. When the pilot in question turns out to be a CFI giving a lesson, head-shaking turns to forehead slaps.
We still marvel at one accident that occurred more than a decade ago during a dual night cross-country down in Texas. According to their written report, “The CFI and student discussed the low fuel status while overflying” the last airport along their route, but “elected not to refuel.” About 10 miles south of their home base, the “amber colored low fuel warning light illuminated,” followed a few minutes later by an emergency autorotation into the trees. Neither was injured, but the landing was hard enough to separate the tailboom. And why did they choose not to stop for fuel? It seems that only self-service was available, and neither had brought a credit card.
This might be a good vehicle for reminding your instructors that just because they can’t get fuel doesn’t mean they don’t still need it. “Better to be down there wishing you were up here than vice versa” never applies much more than when the engine goes quiet over a dark landscape. There are worse things than spending the night at an unfamiliar airport, and in this case that wasn’t their only option. The field they passed was only 22 nm from their base, a straight shot by highway. Maybe they could have stopped and made a phone call?