How To Avoid Misfueling

Aircraft refueling
Credit: Adobe Stock/murmakova

A line service technician is a lifesaver, a term that isn’t used humorously. These are the individuals who literally pull the trigger on something—a fuel nozzle--that if not used correctly, can kill those in an aircraft or innocent people on the ground.

In the context of aircraft misfueling, pilots understand it is ultimately their responsibility to ensure an aircraft is properly fueled. Therefore, many training resources are pilot-centric, but unless a pilot was once a line service technician at one point in his or her career, many do not have familiarity of the line service technician’s side of the coin, or how they are trained.

“The first conversation I have when I hire a new line service tech, pretty much immediately after they’ve filled out their new-hire W2s, is the seriousness of aircraft misfueling,” says Ryan Gauger, president of Jet West, an FBO at the Salinas Municipal Airport in Salinas, California. “I always stress to never be fearful of reporting a misfueling right away. The problem can be fixed, and just because fixing it may be expensive, it’s certainly worth way more to be able to sleep soundly at night.” 

Gauger has trained hundreds of rampers over the course of nearly 30 years. He not only is an experienced pilot, but also an experienced line service technician. Full training for a line service technician at Jet West takes about a month and follows guidelines outlined by the National Air Transportation Association (NATA).

NATA offers an online certification course for pilots, FBO managers, customer service representatives and line service technicians to receive training on aircraft misfueling prevention. It takes about 15 minutes. As a pilot, it certainly will not hurt to take the line service technician’s version of the course. 

In a nutshell, line service technicians are trained to strictly adhere to what NATA refers to as “The Big Three,” which consists of fuel orders, selective spouts and grade verification. The three components of a fuel order include the fuel grade, fuel quantity and aircraft’s registration number. If any piece of this basic information is absent, a line service technician is not technically authorized to pump fuel into the tanks. 

For example, if a fuel order says to pump 500 gallons of Jet A in ABC Aviation’s gold-colored 2002 Falcon 900, the fuel order cannot be fulfilled. What’s missing? The registration number. On a busy ramp in South Florida during the wintertime, there may very likely be more than one Falcon 900 on the ramp, and ultimately the most foolproof way to identify the correct Falcon 900 is by tail number.

Keith Clark, quality control and technical representative at Phillips 66, provided an example of aircraft misidentification that resulted in a fatal crash of a Piper Malibu in February 2015 (see webinar, “Verify Fuel Type: A Pilot’s Story,” A Piper Malibu and Meridian are very similar-looking aircraft, except a Malibu takes avgas while a Meridian takes jet fuel. At this particular airport, many Malibus were being converted to turbine aircraft, which takes jet fuel. The size of the fuel opening on the wing was not adjusted during these conversions, which is what led to the line service technician’s misinterpretation. The pilot never told the technician what type of fuel to use, and the ticket was never verified. This ultimately caused a fatal mistake only seconds after take-off.

Mitigation against aircraft misfueling has improved over the decades, with advancements that have included selective spout size and filler port protocol (avgas will have a maximum spout diameter of 1.97 in., while Jet A spouts will have spout diameters of 2.66 in.), nozzle color designations (red for avgas, black for jet fuel) and single point fueling, which makes misfueling an aircraft foolproof compared to over-wing fueling. However, despite these advancements, misfuelings continue to happen alongside new challenges that did not exist in the past.

New Concerns

Operating in California, where complicated energy regulations are typically more prominent than in other states, Gauger mentioned how a new misfuelling concern can be found between diesel exhaust fluid (DEF) and Prist, an aviation fuel system icing inhibitor. In other words, Prist is used to prevent water from forming into ice that could block engine filters. It is an additive that is completely harmless to jet fuel, however its appearance, and even the containers it is delivered in, is strikingly similar to DEF, the same fuel that is used to power the fuel trucks at FBOs.

New fuel trucks have DEF requirements that need to be followed, and due to DEF’s interchangeable features with Prist, Gauger has appointed one line service technician who is the only authorized person other than himself to oversee changing Prist in the fuel trucks.

With fuel suppliers being at the front lines of quality control issues such as this, FBO managers and line service techs inevitably become the messengers to the rest of the industry as new fueling practices and regulations continue to evolve.

Despite any new challenge however, one thing is not intended to change anytime soon--the simplicity of fulfilling a fuel order. It is not supposed to be hard, which is what can potentially make it dangerous. Therefore, the core of any lesson on aircraft misfueling, no matter who you ask, is communication.


“You can never overcommunicate,” says Otto Wright, general manager of Modesto Jet Center at the Modesty City–County Airport in Modesto, California. Over the course of his career, he has been involved in fueling operations all over the world, where pilots and the ground handlers who were fueling their aircraft did not speak the same language. In his experience of seeing aircraft misfuelings occur, “bad communication has usually been the primary cause. For this reason, some operators require the pilot to be present during the fueling procedure. After all, line techs know how to fuel an airplane, but not everyone knows how to communicate.” 

When arriving at an FBO, a pilot would probably rather head into the FBO for some coffee and a climate-controlled setting as opposed to remaining outside during the fueling process. This is a natural tendency, but it cannot come at the expense of lazy communication. 

When asked about certain pilot tendencies that annoy line service technicians the most, Wright was quick to answer:  pilots who will not talk to them. Unsurprisingly, Gauger also mentioned that friendly pilots make line techs the best they can be. “The best training I ever received as a line guy came from pilots who cared. Those people shaped me into who I am today, and I know they are the ones who do the same for the line service techs here today.” 

Therefore, the next time your aircraft fuel order is being filled, remember that the people behind the fuel lines are as critical to the success of the industry as the fuel that provides the thrust to your engines.