When Mode Reversion Happens:
- Autopilot or Flight Director Mode Changes:
If a managed mode (like NAV or CLB) is lost due to a discontinuity or pilot action, the system reverts to a selected mode (like HDG or V/S) so the pilot retains full control. - Autothrust Mode Changes:
If autothrust loses its managed mode (e.g., due to a thrust lever position mismatch), it reverts to SPEED mode, requiring the pilot to manually adjust thrust or re-engage the correct mode. - Vertical Mode Reversion Example:
If a managed climb (CLB) cannot be maintained (due to ATC instructions or altitude constraints), the system reverts to V/S or OP CLB, giving the pilot manual control over the climb profile.
Why Mode Reversion Matters:
It prevents unexpected aircraft behavior by ensuring:
- The aircraft doesn’t get “stuck” without a defined mode.
- Pilots remain aware of the active guidance mode.
- The crew can easily assume manual control if needed.
Essentially, mode reversion is Airbus’s way of saying: “Hey, something changed—I’m switching to a simpler mode you can directly control.”