Bad Aircraft Fuel Level Indication Can Lead to Aircraft Fuel Starvation.

Really Where's your Proof 

Yes I know you have read every publication put out by AOPA and the FAA and they clearly say fuel level indication is clearly a pilot error issue.  In NTSB reports they have a rubber stamp that reads like the following :

"The pilots improper pre-flight and inflight planning, which resulted in fuel exhaustion."

What most in the general aviation community opinion on this issue is referred to as Fundamental Attribution Error.  (FAE) This is where we naturally blame people, even when circumstances or conditions are the primary issue.  

Last week I wrote a blog with the intentionally provocative title: "Let's Legislate Accurate AIrcraft Fuel Level"

For this I received the expected typical responses below: 

"How about we simply look at the number of people that have fuel related accidents and see if they did a proper preflight ...which...since you keep going by FAR's is required. If they didn't do a preflight correctly...they are poor pilots...and if they are poor pilots...gauges won't make a difference. You can't save people from being stupid"

"So, how much of this is lack of awareness, poor training or just laziness I do not know. But this is one of the most preventable accidents out there that keeps happening on a regular basis. I am not convinced an AOPA video will change that.  That is the real crime. They are still happening twice a week and none of them have to."

You would actually expect this pilot response to the provocative inquiry.   In looking at this as a pilot cultural issue or a FAE  the concept of  "Just World Phenomenon" features prominently.  This is the belief that people get what they deserve and deserve what they get.   


Unfortunately, the just-world hypothesis also results in a tendency for people to blame and disparage victims of an accident or a tragedy.  It is actually a protective strategy of the mind, providing mental separation from those kind of pilots that run out of fuel.   It won't happen to me, I am not like one of those pilots.

Sorry - These are random events and they happen to good pilots - I have a files and files from Transportation Boards across the world - you are not immune.  You have a doppleganger who was just as careful as you are and ran out of fuel in their aircraft.   I am sorry to burst the protective bubble.

What appears to happen in General Aviation is that, blame for fuel starvation, falls squarely on the those pilot shoulders .  This appears to be cultural phenomenon among pilots of all types.  The primary message we hear is that education will cure the miscreants, those bad pilots that will always get into trouble.

Very rarely do we delve into the situational factors of the fuel starvation issue at hand.  Our cultural bias doesn't allow that possibility.

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Fuel indication in aviation is loathsome at best - it is not a deep dark secret that most aircraft fuel indication systems are marginal from the start. 

 When you compound a marginal system with poor or no maintenance,  you can make a general statement that a functionally inoperative fuel gauge is common place in aviation.  

This is illustrated by responses from a General Aviation News inquiry as to what pilots felt about general aviation fuel level indication.

"Maybe they’re also more in the habit of keeping an eye on the clock in flight, even sneaking the occasional glance at those notoriously inaccurate fuel gauges." 

"Airplanes are legendary for having inaccurate fuel quantity gauges" 

"These devices are notoriously inaccurate, showing empty when there are gallons left in the tank and showing full for the first 1/2 hour."

"Aircraft fuel gauges can be notoriously inaccurate." 

"Without a means of measuring fuel flow, you must rely on the aircraft fuel gauges or total time of flight. Aircraft fuel gauges are notoriously inaccurate (they are only required by the FAA to read accurately when displaying empty)." 

"Aircraft fuel gauges have a well-deserved reputation for being unreliable and the FARs only require that fuel gauges read correctly when they are empty!" 

"Second, as others have said aircraft fuel gauges have historically been
poorly designed and grossly inaccurate.  Many will indicate something significantly different in a climb vs a descent and there are some airplanes with fuel gauges that are designed to read full until a substantial amount of fuel has been consumed." 

"Don’t bet your life on your fuel gauges, visually check the fuel level by “dipping” all tanks. Some aircraft models have notoriously unreliable fuel gauges." 

"All light aircraft gauges are notoriously, infamously and reliably, unreliable." 

"Sounds great in theory, but I have not yet seen an accurate Cessna fuel gauge, Ever. A fairly expensive AD would be the only thing that would ever change that."

I don't think a statement that  "Aviation fuel level indication could be improved" would fall very far from the mark. 

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Better fuel indication will lead to better decisions and appropriate warnings in aviation.  

While it seems obvious to a layperson

Strangely, Thats not the popular opinion in GA.  But here is the proof. 

EASA (European FAA) - In a Transport Aircraft study for revisions to required powerplant instruments.  EASA showed that better fuel indication would have improved the result of the 65 incidents and accidents in Transport AIrcraft - well over 70% of these accidents/incidents could have been avoided.  Transport aircraft are not GA, but it is the same mode.

CASA (Australian Civil Aviation Authority) Requires that aircraft fuel Indication in Australian aircraft meet a performance standard, every 4 years.   The reasons cited are improving the fuel starvation incident and accident rate. 

TSBC (Transportation Safety Board of Canada) Makes findings of faulty fuel indication a factor in fuel starvation events.  They point to the wide use of fuel sticks as an indication that fuel level reliability could be improved in aviation

 The fuel quantity indicators on this type of aircraft were not reliable. As a result, the pilot could not be sure of the quantity of available fuel in the left tank during flight.

Tests on the components of the fuel level indication system established that the only time the fuel level in the wing tank was shown correctly was when the tank was empty 

The Bell 214B and Bell 205 flight manuals be modified to provide information regarding the inaccuracy of fuel quantity indications, thereby allowing pilots to make informed decisions in the event of a loss of fuel boost pump pressure. 

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Cognitive Bias 

While these two points are associated with the same system and appear plain as day 

1. General Aviation Aircraft have inaccurate fuel level indication.
2. General Aviation Aircraft are prone to fuel starvation and fuel exhaustion.

A general aviation pilot won't recognize those statements as connected. 

Why: 

Anchoring Bias -  The tendency to rely too heavily, or "anchor", on one trait or piece of information when making decisions (usually the first piece of information that we acquire on that subject.

Pilot's are told to never trust the fuel gauge on the first training flight. 

Availability Cascade A self-reinforcing process in which a collective belief gains more and more plausibility through its increasing repetition in public discourse (or "repeat something long enough and it will become true.

Bandwagon Effect The tendency to do (or believe) things because many other people do (or believe) the same.

AOPA, FAA continually tell us that we need to use proper pre-flight procedure including sticks.

Confirmation Bias The tendency to search for, interpret, focus on and remember information in a way that confirms one's preconceptions

Aircraft fuel gauges only have to be accurate at zero 

You're only interested in selling senders  

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I have a passion for European Sports cars of the 50's and 60's  and I was talking with a group of MG-TC owners.  The subject of fuel indication came up and the MG owner brought out his calibrated stick.   MG T Series cars don't have a fuel gauge, they have a warning light, and Old British cars being what they are the warning light isn't a trusted component or indication of anything of merit.    

I mentioned that small aircraft use a stick as well to determine fuel quantity.  There were lots of raised eyebrows and a few quizzical looks.    The very first statement I heard was.

  "I bet they run out of gas"

  followed by 

"They can't just pull over and check with the stick can they"

I told them the various reasons why,  and they asked if something was being done to improve that.  

I told them sadly no.  A pilot will go out today after purchasing a new aircraft and obtain a stick to measure their fuel.  

It's  startling commentary, that in aviation, we use fuel measurement methods and techniques to prevent running out of fuel that were common on minimal equipment British sports cars of the 40's & 50's.  

I hope it makes us think.

PA28 Lands on a Parkway

Instructor-Pilot Lands Stalled Single Engine Plane Safely on Palm Coast Parkway

FLAGLERLIVE | MARCH 13, 2013

The Piper after it had been pushed off Palm Coast Parkway, sitting in the setting sun as onlookers took in the scene. Click on the image for larger view. (© FlaglerLive)

Phoenix East flight school’s Raul d’Souza is a hero: the young instructor was piloting a plane late this afternoon, practicing emergency landings with a student, when the plane ran into engine troubles–and forced D’Souza, 34, to execute an emergency landing in the heart of Palm Coast. He did so nearly flawlessly.

Raul d’Souza, a new Sully Sullenberger, immediately after the landing. Click on the image for larger view. (© FlaglerLive)

With him was Joo Lee, 33, who looked distinctly shaken from the experience. They both smoked, paced, sat, and smoked again soon after the landing. They’re both based at Phoenix East Aviation, on Pearl Harbor Drive in Daytona Beach. D’Souza, who’s been at the flight school since at least 2004, maintains a YouTube page of favorites that includes several video clips from the flight school.

An SUV–or at least a large white car–had to do an evasive maneuver as the eastbound plane negotiated the two rather narrow lanes of Palm Coast Parkway west, and a huge semi, carrying cars, was also on the road; the plane faintly clipped the truck, but managed to land on the road. The truck had been parked on the shoulder, having just picked up a Mercedes from Parkway Self Storage. The plane clipped its left-front guide-pole with the marker light on its left wing, which shattered, leaving tiny and still-visible fragments on the fender above the truck’s left-front-tire. The plane also clipped the air cleaner, which was dented.

The single-engine Piper, built in 1968, landed safely at 6:45 p.m. on Palm Coast Parkway, just west of Belle Terre. The plane sat on the road for less than 20 minutes before authorities and one of the two occupants of the plane pushed it off the road and parked it at the entrance of Parkway Self Storage. The wesbound lanes of Palm Coast Parkway were shut down only briefly.

The plane belongs to Daytona Aircraft Leasing Inc., based at the same address as the flight school. D’Souza had reported engine trouble to the Daytona airport’s tower just after 6:30 p.m. Authorities in Flagler got the call of a plane in distress at 6:37 p.m., when dispatch announced an airplane emergency, describing a plane approaching Palm Coast Parkway from the west, toward the east, and possibly looking to land there. Shortly afterward, the landing took place.

The pilot and his passenger declined to be interviewed, referring questions to their safety supervisor, who was on his way from Daytona Beach. The Florida Highway Patrol was investigating the incident, which it categorized as a crash the moment the plane struck the truck.

Hayden Gordon, whose truck the plane clipped on its landing approach. Click on the image for larger view. (© FlaglerLive)

Hayden Gordon, 52, has owned the truck since 1999, and said he’d never had any road incident resembling his experience Wednesday afternoon. He’s based in Port St. Lucie. He was on his way to New York City, after starting to pick up cars in Miami. He had three on the truck. “I didn’t really see it,” Gordon said of the plane’s approach. “I was parked here, I’d just put the car up, and I was right here, getting ready to chain it” he said, describing his position to the right of the truck, with the truck blocking his view of the parkway. “Then I hear the sound, I hear it go boom. So when I spin around I saw the plane. There was a car coming. The car went right under. The car went right under it, yeah?” It was a white car. “And I saw the plane hit the ground and run out.”

Gordon ran down to see the pilots, who had immediately bailed from the plane and run to the south shoulder of the road, on the grass. “It kind of scared me a bit, you know,” Gordon continued, after he’d realized what had unfolded, but “they were fine,” he said of the plane’s occupants. “The guy said his engine went out, he tried to start it but it wouldn’t start.”

No NTSB Action 

Aircraft Fuel Totalizers - A Self Fuel Filling Prophesy

One of the more difficult things to measure is liquid fuel on a moving vehicle.  

This is true of aircraft, boats and heavy equipment.  

By it's very nature, liquid fuel refuses to stay still.

So to address these issues with fuel level sending technology,  we have turned to fuel flow instruments and fuel totalizers.  

These instruments measure the fuel flow to the engine and remove that fuel volume from an owner/operator entered starting fuel value.  They can give you a  knots per gallon indication. 

This can be done by several methods - we can count injection pulses and duration or we can get a sensor to measure fuel on the way to the engine,  and in injected engines fuel on the way back to the tank.   There are several sensor types that will perform this function

Some of our cars do the same thing - only they reset when we fill the tank or in other words when the fuel level reaches full.

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Many owners will swear by the fuel totalizer and it's uncanny accuracy.

I filled the tank and then burned 35 gallons of fuel.   When I refilled - I put 35 gallons back into the tank.  

Sounds good - and a justification for the expense of having this equipment installed - However an aircraft tank filled in the same manner and in the same location - the fuel totalizer is a self - fuel filling device.

• I will never run out of fuel with this equipment installed.

• I don't need fuel gauges 

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So what does the FAA say about fuel totalizers 

Digital fuel flow computer systems have a fuel flow transducer that directly measures the fuel being fed to the engine.

The fuel flow transducer may be a small paddle wheel, an impeller, or spring-loaded movable vanes. 

Digital displays with a fuel computer also allow these instruments to display total fuel consumed, total fuel remaining, and time remaining at the present fuel
flow rate for fuel management. Overall accuracy for fuel remaining and time
remaining readings depends on the transducer processing unit and display.

The largest possible error is the initial fuel supply, which is entered by the pilot at the start of each flight. Errors in the initial fuel supply may be caused
by an uneven ramp, unusual loading, volume changes of the fuel because of
temperature variations, malfunctions in the fuel system such as leaks,
siphoning actions, collapsed bladders, and other factors.

So, total fuel remaining should be verified with the fuel quantity indicator. According to § 23.1337(b)(1), fuel quantity indicators are required to be calibrated to read "zero" during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply. Therefore, fuel quantity indicators should be used as the primary fuel-remaining instruments.

Fuel quantity indicators that are inaccurate should be periodically calibrated, repaired, or replaced, as necessary, to ensure reliable readings.  

Taken from  FAA AC 23-17C

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The only issue with the FAA message above is that it was written for aircraft engineers, certifying new aircraft or modifications -  

It really should be shared with the pilot and aviation maintenance community.   

Why not?

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