By Robert N. Rossier, EAA 472091
This piece originally ran in Robert’s Stick and Rudder column in the June 2023 issue of EAA Sport Aviationmagazine.
One of the first things we learn in our initial pilot training is to check the fuel quantity as part of our aircraft preflight inspection. We remove the fuel caps and visually check the level. If less than full, we typically use a “stick” calibrated to the specific aircraft to determine the quantity of fuel. We do this while the aircraft is on level ground to ensure a correct reading. While we may check the indications of the fuel gauges, we are often warned not to rely on them entirely — unless they read zero.
Later on, as our training progresses, we learn to determine the quantity of fuel needed for a flight. We can calculate the fuel needed for climb and for cruise based on power settings and proper leaning of the mixture. We use the forecast winds aloft and route of flight to determine how long it will take us to reach our destination. We add a contingency to ensure we have adequate fuel reserves, as required by regulation. On top of that, we might add some additional fuel quantity to account for the vagaries and unknowns of flight, not to mention Murphy’s law.
Even with all the training, knowledge, and warnings, pilots still occasionally find themselves running out of fuel while airborne. Despite our inherent fear of engine failure, for which we train incessantly, its most common cause is fuel exhaustion.
So, how exactly is it that pilots find themselves in the unenviable situation of piloting a glider when they intended to fly to their destination under power? While by no means a thorough examination of the malady, a quick review of NTSB reports of recent fuel exhaustion accidents helps us identify what goes wrong and serves as further warnings and reminders for us all.
An Important Lesson — Learned the Hard Way
A student and instructor were planning a night training flight in a Cessna 172. During the preflight inspection, the student noted that the aircraft had flown 1.2 hours since its last refueling.
Although she visually inspected the fuel tanks, she didn’t have a fuel dipstick to determine the actual fuel quantity. She reported to the instructor that the tanks were “a little less than full.” The instructor performed a preflight inspection as well but only checked the right fuel tank.
The two departed from North Perry Airport (KHWO) in Hollywood, Florida, and flew to Naples Municipal Airport (KAPF), in Naples, Florida, where they performed 11 stop-and-go landings, and then they headed back for KHWO.
About 3 miles from KHWO, the engine lost power, at which time it was noted that both fuel gauges were stuck between 1/2 and empty. Repositioning the fuel selector from the “both” position to the “left” and then the “right” tank positions failed to restore engine power. It is unclear from the report what other actions may have been taken, but during the forced landing, the airplane impacted trees and a stop sign, causing substantial damage.
The post-crash investigation determined that the right fuel tank was empty, and only about 2.5 gallons of fuel remained in the left fuel tank. The fuel selector had been set between the “both” and “right” fuel tank positions. The report also noted that the airplane’s published total unusable fuel amount was 3 gallons. Based on the hour meter, the airplane had been operated for about 4.5 hours since the fuel tanks had been filled.
Mistaken in a Mooney
The pilot of a Mooney M20J had just taken off from Howell, Michigan (KOZW), on a 20-nm flight to Pontiac, Michigan (KPTK), when the situation began to go awry. The pilot had estimated, based on previous fueling and flight time, that the aircraft had 19 gallons of fuel remaining. This was confirmed by a fuel gauge reading a quantity of 30 gallons.
But shortly after departure, his engine began running rough. The engine quickly smoothed out, and with all engine instruments reading normal, the pilot pushed on toward his destination.
Nearing his destination, the pilot had second thoughts about the flight and decided to return to his home airport. Cruising at 4,500 feet, the engine suddenly quit, forcing the pilot to execute a forced landing in a corn field, which resulted in substantial damage.
The post-accident investigation determined that there was no fuel in the right tank, and only 6.5 gallons in the left. However, the right fuel tank indicator showed the tank was half-full.
It is unclear from the report what steps the pilot took after the engine quit to restore power, but clearly the false indication would have complicated his efforts to resolve the problem. Like we’re so often advised, we should not rely on fuel tank indicators alone.
Penny Wise and Pound Fuelish
The pilot of a Cessna 177 Cardinal had been visiting a family member near Henniker, New Hampshire (NH86). Following a preflight inspection, he was headed home to Stow, Massachusetts (6B6).
The flight should take only about an hour, but with only 9 gallons in the left tank, and none on the right, the pilot had planned a fuel stop along the way.
The pilot departed with the fuel selector set to the left tank and climbed to 2,800 feet. Approximately 6.7 miles from his intended refueling point, the engine began to sputter and then quit entirely, forcing the pilot to make an emergency landing in a parking lot, where the aircraft collided with obstacles and suffered substantial damage.
Not surprisingly, the accident investigation determined that both fuel tanks were empty. Less surprising were the other errors the pilot had made in his planning and procedures.
First, he had relied on a single, rule-of-thumb fuel burn number, rather than calculate the actual fuel needed for the trip. Although he had stuck the fuel tank, he used a stick not calibrated for that aircraft. Finally, he passed by three other airports where fuel was available in favor of landing at one where fuel prices were 20 cents per gallon less.
Clear Reminders
No one is perfect. We all make mistakes. But when it comes to fuel management, it seems there is little room for error. We’d all do well to follow established fuel management protocols and observe the following precautions to help avoid fuel exhaustion:
- Always visually check the fuel quantity in each tank and measure the quantity with a dipstick calibrated for the specific aircraft. Do this regardless of when the aircraft was last fueled.
- Use the data in the pilot’s operating handbook to determine the fuel burn for each segment of flight. Estimates can be misleading.
- Use winds aloft forecasts to determine the time required to fly to the destination. Factor in any potential delays or rerouting.
- Remember that the FAA-required fuel reserves are the minimum reserves we should consider. Always add an extra quantity to cope with the unplanned.
- Always verify the fuel selector has been correctly set and is in the appropriate detent.
- Never rely on the fuel gauges — unless they’re telling us we’re low on fuel.
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.