Is Fuel Dumping Bad for the Environment? (& How Often It Happens)


Is Fuel Dumping Bad for the Environment

Yes, in most cases, fuel dumping is bad for the environment. 

Simply put, fuel dumping, also referred to as fuel jettison, is a common practice in the aerospace industry, where an aircraft will dispose of fuel during a flight.

When this occurs, the jettisoned fuel is either released through combustion as an air pollutant or as kerosene directly into the environment.

Here, we discuss both of these occurrences, the frequency of fuel dumping, and its effects.

How Common Is Fuel Dumping? 

According to the most recent report on incidences of fuel dumping by the FAA, they report an average of 15 fuel dumps per year.

However, they do not specify in their report fuel dumps that weren’t reported to them, nor which types of aircraft were responsible.

As such, claims about the frequency of fuel dumping are often contradicting.

The practice generally aims to adjust an aircraft’s landing weight to ensure the craft can land safely.

Before an aircraft takes flight, the amount of fuel it will use is calculated so that when it reaches its destination, it has generally expended the amount of fuel necessary to be a structurally safe weight.

However, if the craft, for whatever reason, hasn’t used up as much fuel as expected, this means it may be too heavy to land safely, and to protect against this, a fuel jettison system is normally built into the craft to relieve some weight if needed.

The circumstances for fuel dumping are regulated by the US Federal Aviation Administration (FAA).

They explain that unless it is for an emergency, the procedure for overburdened aircraft is to adjust their flight path instead to compensate for excess weight by flying for longer and thus burning more fuel that way.

However, since the fuel jettison system is built into the aircraft, it doesn’t appear to be too out of the ordinary for pilots to use their own judgment as to when to dump fuel if they deem that the situation isn’t an emergency, but they believe they haven’t burnt enough fuel for a safe landing (per SKYbrary, aviation safety reference library).

Moreover, there are specific guidelines for how fuel dumping must occur, though, of course, as we’ll discuss, emergencies don’t always allow these rules to be met in practice.

And even where guidelines are in place, the type of aircraft can impact how the fuel is dumped in such situations.

For instance, the FAA only specifies that fuel should be dumped “at least 2,000 feet above the highest obstacle within 5 miles of the route”.

But most aircraft generally fly much higher than this during normal flights, so we can imagine in this scenario that the craft is almost at its destination.

To put this into context, we’ll talk more about the implications and frequency at different flight altitudes and by aircraft on fuel dumping below.

Commercial Plane Dumping

While the FAA has officially noted only a total of 45 fuel dumps from 2018 to 2020 based on their annual average noted above, they told correspondents at Popular Science Magazine in 2021 that they knew of 47 instances of fuel dumping by commercial American airlines.

The difference in these figures is apparent but not necessarily as conclusive as it seems.

For one, the FAA’s official recorded number of incidents is only over US airspace.

It doesn’t note whether these are actually American aircraft or airlines, only that a craft flew across the US and dumped fuel.

Whereas the report given to Popular Science notes every fuel dump made globally by an American Airline regardless of whether the dump was done over the US or not.

It seems unlikely that nearly all of the fuel dumps that took place globally were in the US alone or that American airlines are solely responsible for all global fuel dumping, so it is hard to say which figure is accurate. 

Military Fuel Dumping

Military aircrafts include any flight crafts that can be used for military purposes rather than commercial air vehicles, such as jets, drones, bombers, and helicopters.

We’ve included these aircrafts together because they have different regulations and rules regarding their air-space practices.

And since they are military crafts, they report to specific military air bases as opposed to the FAA directly.

As a result, the comings and goings of these flights and subsequent dumping don’t appear much in public reporting.

However, there are two reports that were released, one in the 1970s and another in the 1980s, which give some suggestions about the frequency of such instances.

Both report a total of nearly 1,000 instances in three years, but we can assume that this number has likely dropped since then, making current predictions difficult.

However, according to one 2020 analysis of unmanned military flights, they suggest that within the design of such aircraft, fuel dumping is a standard procedure during takeoff.

Similar findings in a 2022 review also seem to suggest that fuel dumping is a more regular byproduct of military aircraft activity, as they write on studies of remedial actions carried out to test how aviation fuel could be removed from polluted soil around military areas.

Though, in this review, it’s worth mentioning the study in question was carried out in Poland rather than the US.

Other Vehicle Fuel Dumping

The dumping of fuel, with the exception of aircraft and military dispensation, is illegal without a permit or license, though exact laws vary from state to state, according to US attorney Clay White.

Despite this, there are incidents of illegal fuel dumping in the US. But of the 123 criminal cases that were opened against illegal dumping, the statistics on this do not specify which are specifically related to fuel.

There is no differentiation between the types of crimes committed nor those that involve fuel dumping during active vehicle travel.

However, we do see a report in 2019 of 3000 gallons of tank diesel being dumped in the District of Georgia, for which the state prosecuted as a seemingly one-off incident.

There is a more worrisome mention at sea by the US National Oceanic Atmospheric Administration of the purposeful jettison of petroleum and oil cargo – but again, specific figures on such incidents are notably absent.

What Happens to the Dumped Fuel?

As aircraft are the more common fuel dumpers, we’ll start here:

Typically, if the fuel is released in an emergency situation and not through its fuel jettison system, it will reach the ground as a liquid.

US aircraft carry Jet-A fuel, a type of kerosene grade fuel that has a freezing point, also known as cloud point, of -47 °C (or -52.6°F).

As most aircraft fly at an average altitude of 35,000 feet where temperatures will be -54.2°C (or –65.61°F), the fuel will reach this point during its flight and begin to condense.

If the fuel is dumped during this time, the fuel forms crystalized particles as it transitions from a liquid into a solid and is a mixture of the two states diffused into a cloud of vapor.

Then, as the temperature increases upon the fuel’s descent, it will return to a liquid and potentially evaporate as pressure and temperature increase towards the earth’s surface.

Conversely, if fuel is dumped at a lower altitude, it’ll simply be liquid when released. 

For planned dumps or those that go through the fuel jettison system, it goes through a dump and burn process rather than being released directly.

This is the same as if it were released from the plane’s exhaust as a gas, but burning off the fuel in one go or short powerful intervals rather than slowly over the duration of the flight.

Where kerosene in liquid form can be removed to some extent by remediation such as soil cleaning and water treatment, the answer to kerosene emissions is less simple.

Once a fossil fuel is burnt, it is broken down into various components throughout the atmosphere.

So the general strategy is mitigation through carbon sinks such as woodlands that can naturally absorb greenhouse gasses or manmade carbon removal technologies.

However, as we’ll discuss, carbon isn’t the only bi-product of fuel combustion, making it much more difficult to tackle.

Does Fuel Dumping Cause Pollution?

Yes, fuel dumping can cause pollution. And there are essentially two pathways for this:

Contamination Through Direct Fuel Exposure

If liquid fuel reaches the ground, the main risk will be contaminating whatever it falls into, generally aquatic or terrestrial habitats.

For instance, research shows that kerosene contamination of water supplies has a particularly toxic impact on aquatic plants.

It causes an effect known as chlorosis, which is the yellowing of leaves due to a lack of chlorophyll, the pigment that helps plants and algae to absorb light from the sun, eventually resulting in the plant’s death.

However, the toxicity of kerosene pollutants isn’t limited to aquatic plants.

Similar research found that even at low concentrations, kerosene induced high mortality in microbial species as well, suggesting serious environmental consequences on other species and potentially humans.

This is likely because pollution of water supplies is rarely limited to the water itself, and following the water cycle, if not directly contaminated by falling kerosene, it can reach terrestrial habitats, affecting soil and vegetation.

Once it reaches these areas, studies show it can inhibit vegetation growth.

In fact, research highlights the soil itself becomes contaminated, killing the bacteria that typically exist there, changing its composition, and, subsequently, the growth of plants for years to come as some species show little to no recovery.

Dump-and-Burn Air Pollution

As for the dump and burn disposal of fuel, the outcome will be the same release of emissions found in aircraft as a whole.

This is when combustion converts kerosene from a liquid to a gas. Accordingly, they release a mixture of pollutants such as CO2, CO, methane, nitrous oxides, and sulfur oxides.

The Environmental and Energy Study Institute reports that such emissions, altogether, contribute to 3.5% of our global anthropogenic warming, 10% of US transport emissions, and 3% of the country’s total greenhouse gas production, increasing the risk of drought, natural disasters and rises in sea levels that come with climate change.

Not to mention, these pollutants cause a number of issues for public and environmental health. For instance:

  • Nitrous oxides – have been known to cause acid rain, respiratory issues, and affect air quality.
  • Carbon monoxide – can cause issues for those with heart disease and affect air quality. 
  • Sulfur oxides – also contribute to acid rain, respiratory issues, and can damage plant growth.

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