Occasionally an accident scenario shows signs of both problems. It may sound extreme, but one way for that to happen is for a flight to begin with one fuel tank essentially empty and the other about to become so.
On August 2, 2017, a Mooney M20K headed out on a short flight from Bartlesville to Skiatook, Oklahoma, for fuel following the aircraft’s release from a repair shop where the exhaust system had been rebuilt.
According to information the 1,000-hour, 56-year-old pilot provided to the NTSB, “he conducted a preflight but did not visually check or measure the fuel in either tank during the preflight, but before flight, he believed the left fuel tank was empty.”
During the runup at 1,800 rpm, the engine had stopped, and “it took a long time to get the engine restarted. Engine would try to start but would not keep running while using boost pump a lot.”
Once the engine had finally started (with battery power running low from all that cranking) the pilot took off, climbed to 2,000 feet msl, and flew around the airport before turning toward Skiatook for fueling.
The pilot recounted, “Upon departure left tank low fuel light was on, right fuel tank light was off and level showed between one-eighth and one-quarter full. Full selector valve was on right fuel tank.”
About seven miles from the destination, the pilot made a position report at about the same time that the low-fuel light for the right tank came on for a few seconds.
From there, the flight narrative speaks for itself: “Reported midfield left downwind leg landing Runway 36. Only left low fuel light was on. Deployed retractable gear. Added first notch of flaps. Slowed airplane to 80 knots. Made left base turn and then left final turn with power pulled back to 15 [inches of mercury]. I had the power pulled back because I was a bit high on left base and when I turned final the glidepath altitude looked correct, added power with no response from throttle. Pumped throttle several times with no response from engine. Low altitude getting critical, no power from engine, made slight right turn to avoid upcoming power lines and 133rd Street where several cars were in my sight. Made off-field landing in the only opening in sight, the plane hit in a large yard right side up and came in contact with nothing other than grass turf.”
The pilot’s response to the question on NTSB Form 6120, which seeks a recommendation from the operator/owner about how the event could have been prevented, only noted that the mishap was still under investigation.
The NTSB, however, took the direct approach, stating the accident’s probable cause as, “The pilot’s improper decision to conduct the flight despite the fuel gauges indicating that there was insufficient fuel for the flight, which resulted in the low amount of fuel in the right tank becoming unported during the multiple turns, and his subsequent improper decision to switch to the nearly empty left tank, which led to a loss of engine power due to fuel starvation.”
As for other takeaways about risk, in analyzing general aviation accidents, the AOPA Air Safety Institute’s twenty-sixth Joseph T. Nall Report notes that about two-thirds of accidents associated with fuel management “resulted from flight-planning deficiencies such as inaccurate estimation of fuel requirements or failure to monitor fuel consumption in flight.”
And ASI offered a practical cautionary note confirmed by more than one aspect of the flight described above: “Accidents caused by poor fuel management or hazardous weather are usually preceded by some sort of warning to the pilot. As such, they can be considered failures of flight planning or in-flight decision-making.”