There are countless factors to consider when it comes to aviation and flying. One aspect that often raises questions is the freezing point of jet fuel. Many people wonder if it’s possible for jet fuel to freeze as an airplane soars through the sky. In this article, we’ll explore the science behind jet fuel freezing and the measures to prevent such occurrences.

In the fascinating world of aviation, an intriguing question often sparks curiosity is whether jet fuel can freeze as an aircraft soars through the sharp, high-altitude skies. Well, on a professional note, let’s dive into this topic.

The short answer is yes: jet fuel can freeze under certain circumstances. However, it is essential to note that jet fuel undergoes a meticulous refining process that maintains a low freezing point, usually around -40 degrees Celsius. This allows the fuel to withstand the sub-zero temperatures encountered during flight. In addition, commercial aircraft have sophisticated heating systems that heat the fuel before injecting it into the engine, preventing any potential freezing issues.

So, while it’s possible for jet fuel to freeze, the aviation industry has taken meticulous precautions to ensure that planes can safely navigate in sub-zero temperatures without encountering fuel-related complications.

Jet Fuel Freeze Point

Jet fuel, commonly known as jet A-1, is a specialized kerosene-based fuel used in turbine aircraft. It is a crucial component that ensures smooth and efficient flight operations. However, like any liquid, it can freeze under specific temperature conditions.

The freezing point of jet fuel, a crucial factor in aviation safety, is a critical issue within the industry. Jet fuel, a highly refined hydrocarbon-based liquid, is typically derived from crude oil and undergoes rigorous processing to meet stringent requirements for aviation use. Its freezing point is a critical consideration, as it directly affects the flow characteristics of the fuel and the possibility of fuel system blockages at low temperatures.

Although the exact freezing point can vary depending on the composition and additives of the fuel, a standard industry benchmark is around -40 degrees Celsius or -104 degrees Fahrenheit. Keeping jet fuel above freezing is essential to ensure an uninterrupted supply of fuel and efficient operation of aircraft, especially in cold weather conditions or high-altitude flights.

There are different types of Jet Fuel, in which the freezing point differs depending on the operational requirements of the aircraft:

Aviation Fuel Grade



Jet A

Kerosine-type fuel

Freezing point -40°C maximum

Minimum flash point of 38°C

ASTM 1655 (US)

Jet A-1

Kerosine-type fuel

Freezing point -47°C maximum

Minimum flash point of 38°C

ASTM 1655 (US)

Def-Stan 91-91 (UK)

Jet A-1/FSII

Kerosine-type fuel

Freezing point -47°C maximum

Minimum flash point of 38°C

Contains 0.1-0.5% Di-EGME as AL-41 or AL-48

ASTM 1655 (US)

Def-Stan 91-87 (UK)


Kerosine-type fuel

Freezing point -47°C maximum

Minimum flash point of 38°C

Contains 0.1-0.5% Di-EGME and approved CI/LI additive

MIL-DTL-83133 (United States)


Kerosine-type fuel

Freezing point -47°C maximum

Minimum flash point of 28°C

GOST 10227 (Russia)


Kerosine-type fuel

Freezing point -47°C maximum

Minimum flash point of 28°C

GOST 10227 (Russia)

People’s Republic of China Jet Fuel No. 3

Kerosine-type fuel

Freezing point -47°C maximum

Minimum flash point of 38°C

GB 6537 (China)

To achieve this, strategies such as fuel heating systems and fuel additives are employed, ensuring optimal fuel performance and minimizing the risks associated with fuel freezing. The aviation industry continues to invest in research and technological advancements to improve the understanding and management of jet fuel freezing, underscoring its unwavering commitment to safety and operational excellence.

Preventing Jet Fuel Freezing: When does jet fuel freeze?

Vertical Profile of Temperature in the Atmosphere

Avoiding the freezing of jet fuel is a critical concern in the aviation industry. When exposed to extremely low temperatures at high altitudes, jet fuel can solidify, leading to engine malfunction and potentially dangerous situations. To combat this problem, aviation professionals employ several methods.

First, fuel additives, such as antifreeze agents, are mixed with jet fuel to lower its freezing point and maintain its liquid state. These additives create a protective layer around the fuel, preventing the formation of ice crystals.

Additionally, it is crucial to ensure that jet fuel storage tanks and equipment are adequately insulated to minimize heat loss and protect them from freezing. Strict fuel temperature control during storage and transport is also essential to identify potential problems and take the necessary preventative measures.

The aviation industry has made significant strides in preventing jet fuel freezes, recognizing that the safety and efficiency of air travel depend on effectively addressing this challenge. By adhering to these professional practices, aviation professionals consistently prioritize safety and ensure smooth operations, even in the coldest conditions.

A laboratory duplication of ice crystals clogging the Fuel-Oil Heat Exchanger on a Rolls-Royce Trent 800 engine is shown in the NTSB Safety Recommendations A-09-17 and A-09-18 photo.

Here are some techniques used to prevent jet fuel from freezing:


Jet fuel is often blended with specialized additives to lower its freezing point further. These additives act as antifreeze agents, improving the fuel’s ability to withstand extremely low temperatures. By incorporating these additives, the freezing point can be lowered to below -40 degrees Celsius.

Jet fuel additives are essential for aviation operations to run smoothly, even in the coldest temperatures. These additives prevent jet fuel from freezing, ensuring safe and efficient flights. With their professional experience, industry experts have carefully formulated additives that effectively lower the freezing point of jet fuel, allowing it to remain in its liquid state even in extreme cold conditions.

By reducing the risk of fuel freezing, these additives contribute to the uninterrupted operation of aircraft engines, ensuring reliable power and performance throughout flight. Airlines and aviation authorities prioritize using such additives to maintain the highest safety standards and ensure smooth operations, particularly in regions with freezing climates or during winter.

Fuel System Icing Inhibitor (FSII)

In operations with very low-temperature climates, or when ascending to altitudes even in tropical climates, the temperature in wing fuel tanks and other tanks can drop to temperatures below freezing; as the fuel cools, approximately one part per million of dissolved water becomes free water for every °F of temperature drop.

Some aircraft without heater systems require FSII to be appropriately mixed into the fuel to prevent water freezing in the fuel system, which could cause clogging in filters and fuel lines due to the formation of ice crystals.


Di-ethylene glycol monomethyl ether is the FSII additive approved for all aviation turbine fuels.

Di-EGME is a colorless liquid completely miscible in water but has limited fuel solubility, especially at low temperatures, so it cannot be pre-diluted with fuel. They absorb water from the atmosphere and tanks. They have a relatively high viscosity and density, making injection and mixing difficult.

Jet Fuel with FSII should not pass through the monitor filters.

Fuel Heating

Jet Fuel Freeze While Flying

Modern aircraft have a fuel heating system that keeps the fuel temperature above freezing. Fuel lines are routed through areas that generate heat, such as the aircraft’s engine, and this heat is used to heat the fuel. This prevents any frozen fuel particles from obstructing fuel flow during flight.

The process involves employing various heating techniques that raise the temperature of the fuel, keeping it in a liquid state even in extremely cold conditions. Using electric heaters or hot air circulation systems, fuel heating protects the integrity of the fuel and ensures the efficient performance of aircraft engines. This indispensable technology, backed by meticulous engineering and rigorous safety standards, allows flights to overcome frigid temperatures and traverse the skies with maximum reliability.


Another method to combat jet fuel freezing is isolating fuel storage tanks and lines. Insulating materials prevent low external temperatures from affecting the fuel inside. Maintaining a controlled environment around the fuel significantly reduces the potential for freezing.

With its ability to retain heat and maintain a constant temperature, insulation is a reliable barrier against freezing temperatures that could compromise jet fuel quality and performance. Insulation minimizes heat loss by providing a protective layer around fuel tanks and piping, ensuring the fuel remains in its optimal liquid state. This is particularly important during winter or in colder regions, where temperatures drop below freezing.


In extremely cold weather conditions, where even antifreeze additives and insulation may not be enough, it is necessary to preheat the fuel. Preheating involves heating the fuel before feeding it into the aircraft’s fuel system. This ensures the fuel is liquid and ready for use, regardless of the external temperature.

This process is essential, especially in regions where frigid temperatures pose significant risks to aviation operations. By employing professional-grade preheating systems, airlines, and aircraft operators can effectively maintain fuel viscosity, preventing it from solidifying and potentially clogging fuel lines or filters. In the highly regulated aviation industry, preheating is considered a critical method of ensuring the uninterrupted flow of jet fuel and protecting engines from cold-related problems.

Conclusion: Can Jet Fuel Freeze While Flying?

Although the freezing point of jet fuel is considerably low, the aviation industry has implemented several measures to avoid any issues related to freezing during flight. Using additives, fuel heating systems, insulation, and preheating techniques, aircraft can continue to operate safely and efficiently even in extremely cold weather conditions.

In addition to preventing fuel freezing and dissolved/free water, it is essential to drain the fuel water to prevent it from entering the aircraft tanks using the methods described above. If you have a “dry” fuel, the chances of ice crystals forming are lower.

So, the next time you get on a plane in winter, you can rest assured that the necessary precautions have been taken to prevent jet fuel from freezing in mid-air.

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