feat(a380x/fms): Secondary flight plans for the A380X

[flogross89]

Summary of Changes

Add SEC FPLN functionality to the A380X. WIP.
Only merge after #10005 .

• Change flight plan instances to readonly
• Refactor performance data from A380's own fmgc class to fms-v2 performance data
• Copy of active flight plan remains connected to active flight plan
• Implement SEC INDEX page
• SEC INDEX: Created type/modifications yes/no
• Adapt F-PLN pages including revisions to SEC FPLN
• Adapt PERF page to SEC FPLN
• Adapt FUEL&LOAD page to SEC FPLN
• Adapt INIT page to SEC FPLN

Out of scope:

• WHAT IF, predictions for SEC FPLN
• Continued updates from active flight plan for performance values if no modification yet
• Different coloring for read-only values (white instead of grey)

Screenshots (if necessary)

References

Additional context

Discord username (if different from GitHub): floridude

Testing instructions

1. Create secondary flight plan via SEC INDEX -> INIT page
2. Create secondary flight plan via CPNY FPLN IMPORT on SEC INDEX page
3. Try swapping SEC with ACTIVE flight plan(s) per FCOM conditions
4. Try different revisions (lateral or vertical) on SEC flight plans
5. Try some normal use cases for the SEC like programming an engine-out procedure and activating it after takeoff. Another option would be to copy the active plan and programming a different destination runway, that you can swap/activate when ATC gives you a different runway.

How to download the PR for QA

Every new commit to this PR will cause new A32NX and A380X artifacts to be created, built, and uploaded.

1. Make sure you are signed in to GitHub
2. Click on the Checks tab on the PR
3. On the left side, find and click on the PR Build tab
4. Click on either flybywire-aircraft-a320-neo, flybywire-aircraft-a380-842 (4K) or flybywire-aircraft-a380-842 (8K) download link at the bottom of the page

[flogross89]

@alexr4339 thanks for the test. Hard to judge whether the issues come from this PR, or the underlying base FMS SEC implementation, or were already present before those changes. Are you able to reproduce the same issue on the A380X and A32NX?
The log messages are expected, they were already present before the PR.

[Benjozork]

Sorry for the late review, only just got to it 😅

[flogross89]

Sorry for the late review, only just got to it 😅

Thanks a lot! Just pushed the changes

[stratavelo92]

Quality Assurance Trainee Report

Discord Username : spottersim
Object of testing : #10429
Aircraft : A380X
Simulator : 2024
Tier of Testing : 1
Date : 14/01/2026

Testing Process:

1. Successful creation of EOSID
2. Successful uplink
3. Successful swapping
4. Noted the following: INSERT NEXT WPT and NEW DEST not possible after origin RWY. SEC 2 and 3 show no bearing and distance info for added WPTs, SEC1 and ACT FPLN after swapping show it correctly. Step climbs on SEC create temporary revisions of the active FPLN. Some constraints at lower levels are saved, whereas constraints at higher levels don't seem to be saved.
5. Successful

Testing Results:
Not Passed

Negatives:
6. R KCCU SEC FPLN PB inop
7. KCCU scrolling keys act on both MCDUs, this results in abnormal behavior when one MCDU shows ACT FPLN and the other one shows SEC FPLN
8. Only SEC1 shows on ND
9. SEC WPTs are shown in green on ND
10. Changing the ZFW in SEC does not change GW (intended?)
11. Format issues
12. L/R MCDU interference - e.g. INSERT NEXT WPT open on R MCDU ACF FPLN, selection of a waypoint on SEC FPLN page in L MCDU --> FORMAT ERROR

Other observations:
13. FLEX always 100% THR
14. Unable to change DEST RW for BTV after RW change in MCDU
15. PWPs sometimes shown/sometimes missing, PRED TO empty during descent
16. VLS for CONF3 and FULL identical and too low
17. Automatic step climb - ACTIVE CRZ LVL 1000ft below current LVL

Conclusions:
SEC FPLNs seem well implemented. However, some issues will show up when interacting with these plans.

Media:
4

8+9

10

11

[BravoMike99]

Quality Assurance Trainee Report

Discord Username : spottersim Object of testing : #10429 Aircraft : A380X Simulator : 2024 Tier of Testing : 1 Date : 14/01/2026

Testing Process:

1. Successful creation of EOSID

2. Successful uplink

3. Successful swapping

4. Noted the following: INSERT NEXT WPT and NEW DEST not possible after origin RWY. SEC 2 and 3 show no bearing and distance info for added WPTs, SEC1 and ACT FPLN after swapping show it correctly. Step climbs on SEC create temporary revisions of the active FPLN. Some constraints at lower levels are saved, whereas constraints at higher levels don't seem to be saved.

5. Successful

Testing Results: Not Passed

Negatives: 6. R KCCU SEC FPLN PB inop 7. KCCU scrolling keys act on both MCDUs, this results in abnormal behavior when one MCDU shows ACT FPLN and the other one shows SEC FPLN 8. Only SEC1 shows on ND 9. SEC WPTs are shown in green on ND 10. Changing the ZFW in SEC does not change GW (intended?) 11. Format issues 12. L/R MCDU interference - e.g. INSERT NEXT WPT open on R MCDU ACF FPLN, selection of a waypoint on SEC FPLN page in L MCDU --> FORMAT ERROR

Other observations: 13. FLEX always 100% THR 14. Unable to change DEST RW for BTV after RW change in MCDU 15. PWPs sometimes shown/sometimes missing, PRED TO empty during descent 16. VLS for CONF3 and FULL identical and too low 17. Automatic step climb - ACTIVE CRZ LVL 1000ft below current LVL

Conclusions: SEC FPLNs seem well implemented. However, some issues will show up when interacting with these plans.

Media: 4 8+9 10 11

From the screenshots it looks like there's some minor other wrong things too.

1. As we don't have VNAV calcs for SEC the EFOB and time should be dashed on the F-PLN page.
2. SEC FUEL & LOAD is showing fuel predictions ( see nr1)
3. DIR TO button visible in SEC F-PLN page
4. SEC F-PLN should not have the "INIT" button visible but instead a return button to navigate towards the SEC INDEX page.

Regarding the GW, the value displayed on the FUEL & LOAD page is not computed based on what is inserted on the page so it not changing seems reasonable.

[flogross89]

@stratavelo92 Thanks a lot for the thorough test! Some of the issues you described weren't caused by this PR, so to keep the scope manageable I'd exclude them here.

In scope for this PR (i.e. I will have a look): 4, 6, 8, 9

Out of scope (i.e. please create separate GitHub issues for these in order to track them): 7, 11, 12, 13, 14, 15, 16, 17

Not a bug: 10