By Robert N. Rossier, EAA 472091
This piece originally ran in Robert’s Stick and Rudder column in the December 2024 issue of EAA Sport Aviation magazine.
Unfortunately, for nearly all of us who fly powered aircraft, the need for fuel to keep our airplanes aloft is undeniable. Yet, despite all our training, fuel starvation and exhaustion continue as common causes of aviation accidents.
Surprisingly, accidents involving fuel management (or mismanagement) are not entirely within the domain of new and unexperienced pilots. Nearly half of the accidents in which fuel exhaustion and fuel starvation occur come at the hands of commercial and ATP pilots. It seems that even experienced and highly trained pilots can succumb to various forms of trickery, miscalculation, or perhaps even complacency.
The following reports highlight a few of the ways we might find ourselves painted into a fuel-free corner, and can perhaps aid us in our pursuit of improved safety in the air.
Multiple Fuel Tanks, Multiple Memory Loss
As pilots, we can recognize that not all aircraft fuel systems are created equal. The more fuel tanks an aircraft is equipped with, the more likely it seems that we can mismanage the fuel system. Such was the case for the pilot of a Piper PA-32 Cherokee Six, which has four fuel tanks — two inboard 25-gallon main tanks and two 17-gallon tip tanks. The fuel selector has five positions — one for each of the four tanks and an “off” position. Each tank carries about a pint of unusable fuel.
At the start of a training flight, the PA-32 in question had a total of 60 gallons of fuel — 17 in each tip tank, 16 in the right main tank, and 10 in the left main tank. In theory, this would have been enough for roughly four hours of flight time (without reserve), assuming a typical 15 gph fuel burn. The pilot and instructor discussed the situation and decided to start the flight on the right main to correct the fuel imbalance between the right and left sides.
A little over an hour into the flight, the engine quit while cruising at about 1,000 feet AGL. Sadly, neither the pilot nor the instructor remembered to switch fuel tanks. They ended up making a forced landing in a field, resulting in substantial damage.
Premix Procedures
While forgetting to switch fuel tanks is a common mistake, forgetfulness may result in other untoward manifestations. In one case, the pilot of an amateur-built Sky Raider had carefully measured out the oil required to be premixed with the fuel, but he set it aside and forgot to mix it with the fuel. He dutifully added 5 gallons of fuel sans oil to the aircraft’s fuel tank and prepared for takeoff. Shortly after departure, the engine failed and the pilot made a forced landing in a nearby field. Only after returning to his hangar did the pilot realize his mistake.
Hot Fuel
Even when sufficient fuel is in the tank(s), getting that fuel to the engine is not always as simple as one might hope. Especially in hot conditions, the problem of vapor lock can be the culprit. Such was the case of the pilot of a Zenith CH 750 flying in the summer Colorado heat. The airplane had been parked on the ramp in near 100-degree Fahrenheit temperatures. When the pilot attempted to start the engine, it refused to run. He moved the airplane to a hangar for about 90 minutes to allow it to cool off. After that, he was able to start the engine and depart.
While en route to his home airport, the engine lost power and the pilot made a forced landing in a plowed field. The airplane nosed over and came to rest inverted, causing substantial damage to the airplane. Fortunately, the pilot received only minor injuries. The probable cause was determined to be fuel vapor lock. It’s unclear if the aircraft had a fuel boost pump, if it was used, or if it would have helped.
Failure to Measure Up
All too often, pilots visually estimate the fuel onboard their aircraft, rather than sticking their tanks to get an accurate determination. About four years ago, the pilot of a Cessna T210 may have made just such a mistake. The pilot reportedly performed a “standard” preflight, estimating the aircraft had 70 gallons of fuel, which was deemed wholly sufficient for a planned one-and-a-half-hour flight.
Nearing his destination, the pilot was cleared to climb in preparation for an instrument approach. During the climb, the pilot noticed the airspeed was bleeding off and the engine not producing power. Breaking out of the clouds, he chose a field adjacent to a lake to make a forced landing. Unfortunately, the glide came up short, and the aircraft crashed in the water.
An investigation of the wreckage determined that the airplane had lost power due to fuel exhaustion. The NTSB report noted that the pilot did not adequately verify the quantity of fuel during the preflight inspection or take into account the fuel burned since the aircraft was last fueled.
Calculations and Estimations Gone Awry
Inadequate planning can also result in fuel exhaustion, as almost occurred in the following scenario. It was the pilot’s first trip flying a Piper PA-28 Archer. Despite all his best attempts at planning, a precautionary landing situation evolved. Note that the Archer carries 48 gallons of usable fuel and burns approximately 10 gph. With full fuel, one might expect adequate fuel for roughly four hours plus a healthy reserve. Of course, a more detailed performance evaluation is required, and the pilot relied on an app to perform the detailed planning.
According to his preflight performance evaluation, he should have been able to make the round trip flight with 45 minutes of fuel to spare — more than enough to meet his required VFR reserve.
After arriving at his destination, the pilot checked the fuel tanks visually. It appeared that he had more fuel remaining than his calculations would have suggested. He also noted that his groundspeed on that leg had been 5 knots higher than anticipated, which squared with his observation of remaining fuel.
Confident that all was going to (or better than) plan, he embarked on his return flight. The pilot climbed to 10,500 MSL, ostensibly to take advantage of more favorable winds and aircraft performance. He reportedly leaned the mixture to peak exhaust gas temperature.
Roughly two hours into the flight, the engine sputtered. Suspecting carb ice, he turned on the carb heat. Then, he quickly glanced at his fuel gauges, which revealed a mere 5 gallons remaining. He switched to the other tank, and the engine roared back to life. Now recognizing his true fuel situation, he safely diverted to a nearby airport.
It’s easy to see how the pilot was misled by what he saw and experienced, but clearly there were lessons to be learned. In retrospect, the pilot should have stuck the fuel tanks at his destination to confirm what he estimated visually. Considering his higher-than-anticipated groundspeed on the first leg, he might have anticipated a lower-than-expected groundspeed on the return flight and recalculated his fuel requirements accordingly.
As these accidents and incidents suggest, fuel management is not always as simple or straightforward as we might anticipate. By redoubling our efforts in preflight preparation, flight planning, and proper fuel system management, we can minimize fuelish behavior and reduce the risks of an in-flight fuel emergency.
Robert N. Rossier, EAA 472091, has been flying for more than 40 years and has worked as a flight instructor, commercial pilot, chief pilot, and FAA flight check airman.