When an airplane lands short of a runway—especially if it touches down on a highway or street near the airport—it always makes the 6 o’clock news. And often it’s reported as a “crash,” even when there is no damage, not even to the airplane.
It’s embarrassing to the pilot and infuriating to the aviation savvy that may be inspired to throw things at the television or go full-on troll on the TV station’s social media. Try to restrain yourself.
A more apt description of these events is an “unscheduled off-airport landing.” And if the reports published by the National Transportation Safety Board (NTSB) are to be believed, an alarming number of these events are often caused by the pilot’s mismanagement of fuel.
Time in the Tanks
One of the first lessons a student pilot learns is not to trust the fuel gauges. This is why you very carefully measure the fuel level in the tanks as part of the preflight inspection and apply that metric to the performance tables in the airplane flying manual (AFM) or pilot’s operating handbook (POH) for the aircraft. It is prudent to round the numbers up.
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If the POH cruise performance table indicates that “at 2,300 rpm on a standard day at a pressure altitude of 4,000 feet, fuel consumption will be 6.6 gallons per hour,” round that up to 7 gallons per hour.
The POH/AFM was based off a brand-new, fresh-from-the-factory airplane, and it is highly likely the one you are flying has some wear and tear on it and probably isn’t as efficient as it once was.
Be conservative with your fuel endurance calculations, and don’t forget to factor in the fuel needed for engine start, taxi, takeoff, and time to climb. Again, round up.
It is also beneficial to note (on average) how long the wait on the ground is before takeoff. If you are flying on a busy summer day, you may be on the ground for 25 minutes or more with that engine running—plan for the worst, hope for the best. Some POHs have a cushion of a few gallons, 2.0 for example, to be applied for engine start, taxi, and takeoff. Fuel consumption during the time to climb is a whole other chart and fuel consumption metric. Don’t skip it.
Yet despite having these reference figures available, there are times when the pilot doesn’t visually check the fuel in the tanks or do the math, perhaps because it’s “just a short flight” and “there’s enough in the tanks.” Please don’t be this pilot. Fuel can be stolen when the aircraft is parked on the ground, and if you don’t visually check the tanks, you might not know it or believe they are really that empty because you know you refueled the last time you flew and you were taught not to trust the gauges.
Art of the Lean
One way to increase the endurance of the fuel on board is to follow the recommended leaning procedures as spelled out in the POH/AFM. Basically, you are adjusting the amount of fuel to the air mixture at your cruising altitude to get increased performance from the aircraft’s fuel supply in terms of both range and endurance.
This practice has been around since the time of Charles Lindbergh. He most famously used the technique during his Atlantic crossing in 1927 and taught it to other pilots during World War II when he served as a technical consultant to the military in the Pacific Theater. He was a test pilot helping the Army Air Corps develop best practices for the Lockheed P-38 Lightning. He showed the pilots how to adjust the fuel mixture and increase the range on the twin-engine aircraft by some accounts up to 400 miles
I have on occasion encountered pilots of rental aircraft who eschew leaning the mixture at altitude, saying, “It’s not my fuel,” because the aircraft are rented “wet,” as in the cost of fuel is factored in. If this is the case, the renter is often reimbursed for the fuel they purchase at another airport—like refueling during a cross-country flight—provided they bring back the receipts.
But here’s the kicker: The reimbursement will be at the cost of fuel at the departure airport. So if you refuel at an airport selling avgas for $6.13 per gallon and the home airport has it for $5.55, that’s what the reimbursement level will be.
Let’s say you purchased 28 gallons to get home—$6.13 x 28 = $171.64 versus $5.55 x 28 = 155.40. The difference of $16.24 won’t buy you another hour in the airplane, but if you are scrimping and saving to finish your flight training, it is something.
Know the Fuel System Quirks
Some fuel systems are thirstier than others. There are so many accounts in the NTSB reports where the pilot thought they had at least 20 minutes to half an hour of usable fuel left, only to experience a loss of engine power as they entered the pattern.
Sometimes it is caused by an aftermarket device that increases the power of the airplane but with that increased power comes increased fuel consumption.
I worked at a flight school that had a Cessna 172 equipped with an aftermarket exhaust system. It made that airplane leap off the ground and perform more like a Cessna 182, but, boy howdy, was it thirsty.
After I sent one of my private pilot candidates on his first solo cross-country flights in that aircraft, I received a flurry of text messages from him. He made it to the destination airport and was concerned about how off his fuel consumption calculations were.
On the way up he had used significantly more fuel than he anticipated using—at least 4 gallons more. He was meticulous about using the POH reference tables. He refueled and came home—and used more on that leg of the flight as well.
I mentioned his experience to another CFI, who noted that he’d had a similar experience with the same aircraft. A mechanic took a look at the system to determine if there was a problem with the system. He said there wasn’t then offered his technical assessment: “The airplane is a fuel pig.”
A placard was added to warn pilots to increase their calculations because of the exhaust system.
