Aircraft Fuel Variables
The tables below indicate the properties for the Simulation Variables that can be used to get and set variables related to the fuel system of the aircraft. For information on the units listed for each variable, please see here: Simulation Variable Units
You can find a complete index of all available SimVars here: SimVar Index
General
The majority of these SimVars are only valid for legacy aircraft that have set up their fuel using the [FUEL] section of the flight model CFG file. Aircraft in Microsoft Flight Simulator 2024 should not be using this fuel method nor these SimVars, and should instead be defining things using the [FUEL_SYSTEM] section of the CFG file and the Fuel System SimVars.
| Simulation Variable | Index | Description | Units | Settable |
|---|---|---|---|---|
FUEL CROSS FEED | Engine Index | Cross feed valve setting. This will return the current setting for the fuel crossfeed for the indexed engine, based on the current status of the simulation and the Cross Feed key events. | Enum:0 = Closed1 = Open2 = Left to Right3 = Right to Left | |
FUEL DUMP ACTIVE | N/A | If 1 (TRUE) then the aircraft can dump fuel. | Bool | |
FUEL DUMP SWITCH | N/A | If set to 1 (TRUE) then the aircraft will dump fuel at the rate set by fuel_dump_rate parameter in the flight_model.cfg file. | Bool | |
FUEL LEFT CAPACITY | N/A | Maximum capacity in volume of all the tanks on the left side of the aircraft. | Gallons | |
FUEL LEFT QUANTITY | N/A | Current quantity in volume of all the tanks on the left side of the aircraft. | Gallons | |
FUEL PUMP | N/A | Currently not used within the simulation. | Number | |
FUEL RIGHT CAPACITY | N/A | Maximum capacity in volume of all the tanks on the right side of the aircraft. | Gallons | |
FUEL RIGHT QUANTITY | N/A | Current quantity in volume of all the tanks on the right side of the aircraft. | Gallons | |
FUEL SELECTED QUANTITY | Selector Index | Quantity of fuel in the tank referenced by the indexed selector. When using the legacy fuel system, this SimVar will return the quantity of fuel in the tank pointed to by the selector you chose with the index. If passing an index higher than the number of selectors - or when using the modern fuel system - it will return the total fuel quantity available. | Gallons | |
FUEL SELECTED QUANTITY PERCENT | Selector Index | Percent or capacity for the tank referenced by the indexed selector. When using the legacy fuel system, this SimVar will return the percentage of fuel in the tank pointed to by the selector you chose with the index. If passing an index higher than the number of selectors available - or when using the modern fuel system - it will return the percentage of total fuel quantity available. | Percent Over 100 | |
FUEL SELECTED TRANSFER MODE | N/A | The method of transfer for the fuel. Each of the available transfer options are explained below:off - Fuel transfer is switched off.auto - Automatically balance the fuel between the Center1 and Center2 tanks to maintain the center of gravity.forward - Fuel will be transferred forwards from the Center1 tank to the Center2 tank.aft - Fuel will be transferred aftwards from the Center2 tank to the Center1 tank.manual - Fuel will be transferred for 1 second from the Center1 tank to the Center2 tank at a rate of 1lbs/s.custom - This requires one or more pumps to have been defined using the fuel_transfer_pump.N parameter in the flight_model.cfg file, as well as their associated electrical circuits. | Enum:0 = off1 = auto2 = forward3 = aft4 = manual5 = custom | |
FUEL TOTAL CAPACITY | N/A | Total fuel capacity of the aircraft for all tanks. | Gallons | |
FUEL TOTAL QUANTITY | N/A | Current total quantity of fuel in volume for all tanks of the aircraft. The actual returned value will depend on the fuel system being used:Legacy fuel system [FUEL]: The value will include any unusable fuel.Modular fuel system [FUEL_SYSTEM]: The value will not include any unuseable fuel.This can be checked using the NEW FUEL SYSTEM SimVar. | Gallons | |
FUEL TOTAL QUANTITY EX1 | N/A | Current total quantity of fuel - including any unuseable fuel - for all tanks of the aircraft, regardless of the fuel system being used. | Gallons | |
FUEL TOTAL QUANTITY WEIGHT | N/A | Current total fuel weight for all tanks of the aircraft. The actual returned value will depend on the fuel system being used:Legacy fuel system [FUEL]: The value will include any unusable fuel.Modular fuel system [FUEL_SYSTEM]: The value will not include any unuseable fuel.This can be checked using the NEW FUEL SYSTEM SimVar. | Pounds | |
FUEL TOTAL QUANTITY WEIGHT EX1 | N/A | Current total weight of fuel - including any unuseable fuel - for all tanks of the aircraft, regardless of the fuel system being used. | Pounds | |
FUEL TRANSFER PUMP ON | Pump Index | Returns 1 (TRUE) if the indexed pump is active. | Bool | |
FUEL WEIGHT PER GALLON | N/A | The weight of the fuel, per gallon. | Pounds | |
NEW FUEL SYSTEM | N/A | Will return 1 (TRUE) if the aircraft is using the modern [FUEL_SYSTEM] or 0 (FALSE) for the legacy [FUEL]. | Bool | |
NUM FUEL SELECTORS | N/A | The number of fuel selectors on the aircraft. | Number | |
UNLIMITED FUEL | N/A | Will return 1 (TRUE) if the unlimited fuel flag has been enabled, or 0 (FALSE) otherwise. | Bool | |
UNUSABLE FUEL TOTAL QUANTITY | N/A | The total amount of fuel in all tanks of the aircraft which is not usable. | Gallons |
Fuel System
These SimVars are dedicated to controlling the modern component fuel system, which you can set up in the [FUEL_SYSTEM] section of the flight_model.cfg. All aircraft made for Microsoft Flight Simulator 2024 should be using this system and these SimVars, and only legacy aircraft should be using the General SimVars and the [FUEL] section of the flight_model.cfg file. Most of these SimVars require the name of the component that they target. This name is given using the following format:
[SimVar]:'[COMPONENT_NAME]'_nFor example:
(A:FUELSYSTEM PUMP SWITCH:'SWITCH_1'_n, Enum)| Simulation Variable | Index | Description | Units | Settable |
|---|---|---|---|---|
FUELSYSTEM ENGINE PRESSURE | Engine Index | The pressure of the fuel coming to the indexed engine. The name is the one defined by the Engine.N parameter. | Kilo pascal | |
FUELSYSTEM JUNCTION SETTING | Junction Name (or index) | This will return the current Option for the indexed junction. The name is the one defined by the Junction.N parameter. | Number | |
FUELSYSTEM LINE FUEL FLOW | Line Name (or index) | The fuel flowing through the indexed line in Gallons per Hour. The name is the one defined by the Line.N parameter. | Gallons per hour | |
FUELSYSTEM LINE FUEL LEVEL | Line Name (or index) | The level of fuel in the indexed line in Gallons. The name is the one defined by the Line.N parameter. | Gallons | |
FUELSYSTEM LINE FUEL PRESSURE | Line Name (or index) | The pressure in the indexed fuel line, measured in KiloPascal. The name is the one defined by the Line.N parameter. | Kilo pascal | |
FUELSYSTEM PUMP ACTIVE | Pump Name (or index) | Whether or not the indexed pump is actually active. The name is the one defined by the Pump.N parameter. | Bool | |
FUELSYSTEM PUMP SWITCH | Pump Name (or index) | Whether or not the indexed pump is enabled. The name is the one defined by the Pump.N parameter. | Bool | |
FUELSYSTEM TANK CAPACITY | Tank Name (or index) | Total capacity of the indexed fuel tank. The name is the one defined by the Tank.N parameter. | Gallons | |
FUELSYSTEM TANK USABLE CAPACITY | Tank Name (or index) | Total useable capacity of the indexed fuel tank. The name is the one defined by the Tank.N parameter. | Gallons | |
FUELSYSTEM TANK LEVEL | Tank Name (or index) | Quantity of fuel available in the indexed fuel tank. The name is the one defined by the Tank.N parameter. | Percent Over 100 | |
FUELSYSTEM TANK QUANTITY | Tank Name (or index) | Quantity of fuel currently available in the indexed fuel tank. The name is the one defined by the Tank.N parameter.NOTE: If the fuel system Version is 2 or below, the index value will be one of the Fuel Tank Selection indices. | Gallons | |
FUELSYSTEM TANK TOTAL QUANTITY | Tank Name (or index) | Total quantity of fuel available in the indexed fuel tank, including any unusable fuel. The name is the one defined by the Tank.N parameter.NOTE: If the fuel system Version is 2 or below, the index value will be one of the Fuel Tank Selection indices. | Gallons | |
FUELSYSTEM TANK WEIGHT | Tank Name (or index) | Weight of fuel available in the indexed fuel tank. The name is the one defined by the Tank.N parameter.NOTE: If the fuel system Version is 2 or below, the index value will be one of the Fuel Tank Selection indices. | Pounds | |
FUELSYSTEM TRIGGER STATUS | Trigger Name (or index) | Whether or not the indexed trigger is active. The name is the one defined by the Trigger.N parameter. | Bool | |
FUELSYSTEM VALVE OPEN | Valve Name (or index) | Whether or not the indexed valve is actually fully opened. The name is the one defined by the Valve.N parameter. | Percent Over 100 | |
FUELSYSTEM VALVE SWITCH | Valve Name (or index) | Whether or not the indexed valve is set to be opened. The name is the one defined by the Valve.N parameter. | Bool |
Fuel Tanks
| Simulation Variable | Index | Description | Units | Settable |
|---|---|---|---|---|
FUEL TANK CENTER CAPACITY | N/A | Maximum capacity in volume of center tank 1/2/3. | Gallons | |
FUEL TANK CENTER2 CAPACITY | N/A | Maximum capacity in volume of center tank 1/2/3. | Gallons | |
FUEL TANK CENTER3 CAPACITY | N/A | Maximum capacity in volume of center tank 1/2/3. | Gallons | |
FUEL TANK CENTER LEVEL | N/A | Percent of maximum capacity of center tank 1/2/3. | Percent Over 100 | |
FUEL TANK CENTER2 LEVEL | N/A | Percent of maximum capacity of center tank 1/2/3. | Percent Over 100 | |
FUEL TANK CENTER3 LEVEL | N/A | Percent of maximum capacity of center tank 1/2/3. | Percent Over 100 | |
FUEL TANK CENTER QUANTITY | N/A | Current quantity in volume of center tank 1/2/3. | Gallons | |
FUEL TANK CENTER2 QUANTITY | N/A | Current quantity in volume of center tank 1/2/3. | Gallons | |
FUEL TANK CENTER3 QUANTITY | N/A | Current quantity in volume of center tank 1/2/3. | Gallons | |
FUEL TANK EXTERNAL1 CAPACITY | N/A | Maximum capacity in volume of external tank 1/2. | Gallons | |
FUEL TANK EXTERNAL2 CAPACITY | N/A | Maximum capacity in volume of external tank 1/2. | Gallons | |
FUEL TANK EXTERNAL1 LEVEL | N/A | Percent of maximum capacity of external tank 1/2. | Percent Over 100 | |
FUEL TANK EXTERNAL2 LEVEL | N/A | Percent of maximum capacity of external tank 1/2. | Percent Over 100 | |
FUEL TANK EXTERNAL1 QUANTITY | N/A | Current quantity in volume of external tank 1/2. | Gallons | |
FUEL TANK EXTERNAL2 QUANTITY | N/A | Current quantity in volume of external tank 1/2. | Gallons | |
FUEL TANK LEFT AUX CAPACITY | N/A | Maximum capacity in volume of the left auxiliary tank. | Gallons | |
FUEL TANK LEFT AUX LEVEL | N/A | Percent of maximum capacity of the left auxiliary tank. | Percent Over 100 | |
FUEL TANK LEFT AUX QUANTITY | N/A | Current quantity in volume of the left auxiliary tank. | Gallons | |
FUEL TANK LEFT MAIN CAPACITY | N/A | Maximum capacity in volume of the left main tank. | Gallons | |
FUEL TANK LEFT MAIN LEVEL | N/A | Percent of maximum capacity of the left main tank. | Percent Over 100 | |
FUEL TANK LEFT MAIN QUANTITY | N/A | Current quantity in volume of the left main tank. | Gallons | |
FUEL TANK LEFT TIP CAPACITY | N/A | Maximum capacity in volume of the left tip tank. | Gallons | |
FUEL TANK LEFT TIP LEVEL | N/A | Percent of maximum capacity of the left tip tank. | Percent Over 100 | |
FUEL TANK LEFT TIP QUANTITY | N/A | Current quantity in volume of the left tip tank. | Gallons | |
FUEL TANK RIGHT AUX CAPACITY | N/A | Maximum capacity in volume of the right auxiliary tank. | Gallons | |
FUEL TANK RIGHT AUX LEVEL | N/A | Percent of maximum capacity of the right auxiliary tank. | Percent Over 100 | |
FUEL TANK RIGHT AUX QUANTITY | N/A | Current quantity in volume of the right auxiliary tank. | Gallons | |
FUEL TANK RIGHT MAIN CAPACITY | N/A | Maximum capacity in volume of the right main tank. | Gallons | |
FUEL TANK RIGHT MAIN LEVEL | N/A | Percent of maximum capacity of the right main tank. | Percent Over 100 | |
FUEL TANK RIGHT MAIN QUANTITY | N/A | Current quantity in volume of the right main tank. | Gallons | |
FUEL TANK RIGHT TIP CAPACITY | N/A | Maximum capacity in volume of the right tip tank. | Gallons | |
FUEL TANK RIGHT TIP LEVEL | N/A | Percent of maximum capacity of the right tip tank. | Percent Over 100 | |
FUEL TANK RIGHT TIP QUANTITY | N/A | Current quantity in volume of the right tip tank. | Gallons | |
FUEL TANK SELECTOR | Selector Index | Which tank the indexed selector is set to. The index is the selector to check (from 1 to 4), and the return value will be the Fuel Tank Selection index.NOTE: This SimVar is only valid for the legacy [FUEL] setup. | Enum |
Fuel Tank Selection
| Number | Description |
|---|---|
0 | Off |
1 | All |
2 | Left |
3 | Right |
4 | Left auxiliary |
5 | Right auxiliary |
6 | Center |
7 | Center2 |
8 | Center3 |
9 | External1 |
10 | External2 |
11 | Right tip |
12 | Left tip |
13 | Crossfeed |
14 | Crossfeed left to right |
15 | Crossfeed right to left |
16 | Both |
17 | External |
18 | Isolate |
19 | Left main |
20 | Right main |