INIT B: LOADING, FIELD ORDER AND PREDICTIONS
INIT B gives the system the mass and fuel information needed for its calculations. ZFW, zero-fuel weight, is the loaded aircraft without usable fuel. ZFWCG is the centre of gravity of that zero-fuel aircraft, expressed against the standard MAC wing reference. Block fuel is the fuel aboard before taxi. The entries describe the aircraft we have actually prepared, so they must agree with loading and fuelling rather than just with what we hoped to load. [26, PDF p. 123]
The loadsheet summarises the flight's mass and distribution. A preliminary loadsheet helps preparation, but final or revised information can change the entries we need. Before start, compare the final data with the actual EFB loading state. If loading is still changing, return to the check after it finishes. The arithmetic can be beautifully neat while describing an aircraft that has not yet reached that loading state. [26, PDF p. 123]
Before starting the engines, page from INIT A to INIT B. With a field labelled ZFW/ZFWCG, our exercise enters 60.0/27.0: 60.0 tonnes followed by 27.0 percent MAC. BLOCK takes 6.0 in the displayed units. Read both accepted mass/CG values separately. The older Thales illustration uses a different combined-field order, so the actual field label takes priority over a remembered example. [26, PDF p. 123] [54, PDF pp. 1-3]
Check the fuel assumptions too. Taxi fuel belongs to the period before takeoff; trip fuel is used in the flight's planning comparison. Reserves have their own purpose in the OFP. Read what the page contains and reconcile it with the plan, rather than adjusting a reserve to make the remaining-fuel figure look more comfortable. Calculated results are then useful evidence about the preparation, not targets we force the computer to display. [26, PDF p. 123] [54, PDF pp. 1-3]
Our teaching case adds 60.0 tonnes of ZFW and 6.0 tonnes of block fuel to give 66.0 tonnes at the stand. Subtract the stated 0.2 tonnes of taxi fuel and takeoff mass is 65.8. Using the exercise's 2.4-tonne trip assumption gives 63.4 at landing and 3.4 tonnes of fuel remaining. That is an independent arithmetic reference. The actual flight's prediction depends on its actual route, conditions and other inputs. [26, PDF p. 123]
With the route and cruise information entered, allow the FMS to calculate and compare its time/fuel predictions with the OFP. A material difference deserves a look at the inputs and route. It does not automatically mean the system is wrong, nor does a plausible destination-fuel figure prove every input right. The practical exercise closes the loop by reading the accepted entries and the resulting prediction together. [26, PDF p. 123]
A convenience transfer still needs that readback. In the dated 24-25 October 2026 V3 issue report, Send to MCDU from Mass and Balance uses live aircraft weights/trim rather than loadsheet data. Compare the accepted result with both the actual loaded aircraft and latest loadsheet, particularly while loading is still changing. Treat the report as a build-specific issue snapshot, with current official status checked for the version in use. [42]
Exercise arithmetic: 60.0 t ZFW + 6.0 t block; 0.2 t taxi and 2.4 t trip. Arrival mass 63.4 t is a planning check, not a forced FMS prediction. [26, PDF pp. 115–117]
IN PRACTICE: INIT B: reconcile the load, then calculate
Before you begin: Engines not yet started. Loading and fuelling state known; final loadsheet and OFP available. Use metric tonnes for the stated exercise and verify the aircraft’s displayed units.
1. Separate requested load from actual load
Action. Open the EFB loading information and establish what is actually aboard. Compare final ZFW, ZFWCG and fuel with the latest loadsheet. If boarding or fuelling is still changing them, finish this check after completion.
Check. You have a final set of actual loading values, not merely the values that were requested earlier in the session. [54, PDF pp. 1-3] [54, PDF p. 4]
2. Open the preflight fuel-init page
Action. Press INIT and use horizontal slew to reach INIT B while the engines remain off. Check the field labels and units before entering any combined mass/CG value.
Check. The weight/fuel initialization page is displayed. You have not assumed that a field from the historical manual uses the modern Fenix order. [26, PDF p. 123]
3. Enter the mass and centre of gravity
Action. For a field labelled ZFW/ZFWCG, enter 60.0/27.0 for the exercise. If the displayed order differs, follow that label. Read the accepted weight and CG separately against the final data.
Check. ZFW is 60.0 tonnes and ZFWCG is 27.0 percent MAC for the teaching case. The two numbers have not been transposed. [26, PDF p. 123] [54, PDF pp. 1-3]
4. Enter block and taxi fuel
Action. Enter 6.0 in BLOCK for the exercise and verify TAXI against the planned 0.2 tonnes. For a current sector use the actual block and planned taxi fuel; review reserve assumptions from that OFP.
Check. The preflight fuel inputs agree with the planning case. Reserves have not been reduced merely to make an extra-fuel figure look more comfortable. [26, PDF p. 123]
5. Let the FMS calculate its prediction
Action. With the route, cruise reference, mass and fuel entered, allow the predictions to compute. Compare destination fuel and trip/time results with the OFP. Investigate a significant difference through the inputs and route.
Check. The FMS has a coherent basis for prediction. The exercise’s 2.4-tonne trip figure is a planning comparison, not a value to force into a calculated field. [26, PDF p. 123]
6. Keep an independent arithmetic reference
Action. For the teaching dataset, compare the 66.0-tonne ramp mass and 65.8-tonne takeoff mass with the stated block/taxi assumptions. The simple destination reference is 63.4 tonnes with 3.4 tonnes of fuel remaining.
Check. You can explain the arithmetic independently. Differences caused by a changed flight or loading state are identified rather than hidden by editing the wrong field.
7. Read back a convenience transfer
Action. If you use Send to MCDU, read the resulting entries against both the live aircraft and latest loadsheet. The V3 issue reported on 24–25 October 2026 sends live weights/trim rather than loadsheet data.
Check. A transfer is followed by verification. While loading is changing, the first transferred values are not mistaken for the final load information. [42]
Complete when: Accepted weight and fuel entries match the loaded aircraft and latest load information. Calculated predictions are checked rather than overwritten to match the exercise arithmetic.