What is RFLNG on Boeing 737? (Refueling)

Refueling, also known as RFLNG in aviation terminology, is a crucial process for every aircraft, including the Boeing 737. It involves replenishing the aircraft’s fuel supply to ensure it has the necessary energy to complete its flight safely and efficiently. In this blog post, we will explore the various aspects of refueling on the Boeing 737 and delve into the technicalities behind this essential procedure.

Refueling Procedure on the Boeing 737

The refueling process on the Boeing 737 involves the careful transfer of fuel from the ground into the aircraft’s fuel tanks. Before the process begins, the pilot or flight crew communicates with the ground handlers to provide them with the required amount of fuel for the flight. The ground handlers then prepare the fuel truck and connect it to the aircraft.

On the Boeing 737, the fuel tanks are typically located in the wings. This design allows for a more efficient distribution of weight and enhances the aircraft’s stability during flight. To access the fuel tanks, the ground crew opens the fuel panel covers located on the wings.

Once the fuel truck is properly connected, the fueling process begins. The fuel is transferred from the truck to the aircraft through a specialized fueling hose. The hose is equipped with safety mechanisms to prevent overfilling and spills.

Fuel Capacity and Efficiency

The Boeing 737 comes in various models, each with different fuel capacities. Let’s take a look at some of the popular models and their fuel capacities:

1. Boeing 737-300: This model has a maximum fuel capacity of 19,420 U.S. gallons (73,490 liters).

2. Boeing 737-700: It can hold up to 6,870 U.S. gallons (26,020 liters) of fuel, allowing it to cover longer distances without refueling.

3. Boeing 737-800: With a fuel capacity of 6,875 U.S. gallons (26,040 liters), this model offers similar efficiency to the 737-700.

These figures may vary depending on additional features, such as auxiliary fuel tanks or optional modifications. It’s worth noting that the weight of the fuel affects the aircraft’s performance, including its range and takeoff capability.

Fueling Safety Measures

Refueling operations are conducted with utmost care to ensure the safety of the aircraft, crew, and passengers. Here are some safety measures followed during the refueling process on the Boeing 737:

1. Static Grounding: Static electricity can pose a significant risk during refueling. To mitigate this risk, the aircraft is grounded before fueling begins. Grounding the aircraft effectively discharges any accumulated static electricity, reducing the likelihood of a spark that could lead to a fire or explosion.

2. Fire Safety: Fire extinguishers are readily available during the refueling process. The ground crew is trained in fire safety protocols and is equipped to handle emergencies swiftly and efficiently. The use of fire-resistant materials and anti-spark fittings further enhances the safety of the refueling operation.

3. Fuel Quality Control: Ensuring the quality of the fuel is vital to the proper functioning of the aircraft. Before it is loaded onto the truck, the fuel undergoes rigorous testing and filtration processes to remove any contaminants or impurities. These measures prevent fuel system clogs and maintain the efficiency of the aircraft’s engines.

It’s important to note that the refueling process on the Boeing 737 is not limited to routine flights. In the event of an emergency landing or diversions, the aircraft may need to be refueled swiftly to ensure the continued safe operation of the flight.


Refueling on the Boeing 737 is an essential part of the aircraft’s operations. It involves a systematic procedure to transfer fuel from the ground into the aircraft’s fuel tanks. The Boeing 737’s fuel capacity and efficiency play a crucial role in determining its range and performance capabilities. Safety measures are rigorously followed to ensure the safe and efficient completion of the refueling process. Understanding the intricacies of refueling helps us appreciate the importance of this procedure in the overall operation of the Boeing 737.

For More: What is EXT on Boeing 737? (Extend)