ETOPS / One Engine Out — Three Cruise Strategies, Reliability, Boundary

From the engine's view, this article covers ETOPS and extended one-engine-out operation: the three cruise strategies after an engine failure (PR-AEP-ENG) and ETOPS's dependence on engine reliability. Note on method: the full ETOPS content (diversion-time thresholds, entry/exit, reliability monitoring) lives in the operations manual / performance / FOM and is only lightly covered in the ATA 70 system chapter → here only the engine-view one-engine cruise strategies (PR-AEP-ENG verbatim), with the full ETOPS pointed to the operations chapters.

1. Three cruise strategies on engine failure

When an engine failure occurs during cruise, three possible strategies apply: ‐ The standard strategy ‐ The obstacle strategy ‐ The fixed speed strategy. Unless a specific procedure has been established before dispatch (considering ETOPS or mountainous areas), the standard strategy is used. Note: Pressing the EO CLR key on the MCDU restores...

Per FCTM PR-AEP-ENG, a cruise engine failure has three strategies: ① standard ② obstacle ③ fixed speed. Unless a specific procedure was established before dispatch (considering ETOPS or mountainous areas), the standard strategy is used; the MCDU EO CLR (Engine Out Clear) key restores the normal display.

2. The three strategies

Default standard; ETOPS or mountainous operations establish the obstacle/fixed-speed procedure before dispatch (PR-AEP-ENG). The MCDU EO (Engine Out) mode assists.

3. ETOPS and engine reliability (boundary)

[!note]- ETOPS's dependence on the engine (boundary) ETOPS (extended operations) rests on a twin flying far from a diversion airfield depending on single-engine availability for safety, which demands high engine reliability (monitored on the fleet). But the full ETOPS rules — diversion-time thresholds (120/180 min etc.), ETOPS entry/exit, reliability-monitoring metrics — live in the operations manual / performance / FOM and are not deeply covered in the ATA 70 system chapter. By "not in the system-chapter master library → do not infer the specific thresholds," this article only confirms: ETOPS depends on engine reliability + a one-engine failure cruises on the three strategies; the full rules are in the operations chapters.

4. Counterintuitive point

[!warning]- A one-engine cruise defaults to standard, but ETOPS/mountainous needs pre-dispatch planning The three strategies are not selected ad hoc in flight — default standard; the ETOPS or mountainous obstacle/fixed-speed strategy must be established before dispatch (PR-AEP-ENG). The plan is set on the ground.

Self-test

[!note]- Q1. The three cruise strategies on engine failure, and the default? standard / obstacle / fixed speed; default standard (unless a specific procedure was established before dispatch).

[!note]- Q2. When is a non-default strategy used? ETOPS or mountainous areas, with a specific procedure (obstacle/fixed speed) established before dispatch.

[!note]- Q3. Where are the full ETOPS rules? Operations manual / performance / FOM (not deeply covered in the ATA 70 system chapter — a boundary here).

Key takeaways

References

• FCTM PR-AEP-ENG — three cruise strategies on engine failure (standard/obstacle/fixed speed, default standard, ETOPS/mountainous pre-dispatch) + MCDU EO CLR.
• Cross-chapter operations / performance / FOM — full ETOPS rules (diversion time / reliability; a boundary here).

Independent study material, not an Airbus publication and not endorsed by the manufacturer. Always defer to the current operator FCOM, FCTM, and QRH for operational use.