Aircraft Fueling Calculator (A320 / B737)

Symmetrically distribute departure fuel across tanks and cross-check bowser uplift discrepancies.

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Looking for larger aircraft? Check out our Wide Body Aircraft Fueling Calculator (A330/A350/B787/B777).

Standard Wing Tank Reference Limits

To calculate accurate tank distributions, input your specific aircraft type’s wing tank ceiling limit. Common reference values include:

• Airbus A320 (CEO/NEO): ~6,000 KG per wing tank.
• Boeing 737 Next Generation (NG): ~3,900 KG per wing tank.
• Boeing 737 MAX: ~3,700 KG per wing tank.

The calculator automatically fills both wing tanks equally up to your configured limit before channeling any remaining excess fuel into the Center (CTR) tank.

Formulas & Calculations Used

• Actual Uplift (KG): Converts the physical volume delivered by the fueling truck into mass based on the fuel density.
  Actual Uplift (KG) = Uplift (Liters) × Specific Gravity (SG)
• Calculated Uplift (KG): The net fuel weight increase recorded by the aircraft’s fuel quantity indication system (FQIS).
  Calculated Uplift = Total Departure Fuel (Y) − Total Arrival Fuel (X)
• Total Discrepancy (KG): Measures the absolute weight variance between the truck meter readings and cockpit indications.
  Discrepancy = Calculated Uplift − Actual Uplift
• Discrepancy Variance (%): Displays the percentage deviation. In commercial line operations, a variance exceeding 5% typically requires a fuel log recheck or a technical review.
  Discrepancy % = (Discrepancy / Calculated Uplift) × 100

Specific Gravity (SG)

Aviation fuel density changes continuously based on ambient temperature. To ensure safety and accuracy, international bodies like the Joint Inspection Group (JIG) and ATA Specification 103 enforce strict regulatory guardrails:

• The Legal Range: Standard Jet A-1 fuel must have a Specific Gravity between 0.775 and 0.840 kg/L when measured at the standard reference temperature of 15°C.
• Mandatory Bowser Testing: Refueling operators are legally required to test the fuel density daily (or per batch) and record the actual hydrometer-measured SG directly onto the Fuel Delivery Note (FDN).
• Flight Crew Verification: The flight crew or maintenance engineer must use the exact SG written on the delivery slip – not a guessed or average figure – to compute the final aircraft fuel load.

Using an incorrect or expired Specific Gravity value violates airworthiness standards, as it compromises the accuracy of the cockpit Fuel Quantity Indication System (FQIS) and can cause dangerous structural weight imbalances or unexpected range deficits.

Scope and Limitations

• Three-Tank Layout Only: The logic is hardcoded for a standard narrowbody three-tank system (Left Wing, Right Wing, Center Tank). It cannot process widebody or complex fuel configurations featuring auxiliary or outer wing cells. [For larger aircraft, use Wide Body Aircraft Fueling Calculator (A330/A350/B787/B777)].
• Symmetric Scheduling Only: Automatically splits fuel evenly between both wing tanks up to the specified limit before routing excess fuel to the center tank. It cannot calculate asymmetric loads or custom tank sequencing.
• Static Density Calculations: Uses a single, fixed Specific Gravity (SG) input. The code does not account for real-time temperature fluctuations, fuel stratification, or volumetric thermal expansion.