Cruise Phase: Essential Boeing 787 Tips for Optimal In-Flight Performance
Cruise isn’t just autopilot and coffee ☕—it’s when real flying skills kick in. On the 787, you’re fine-tuning performance, dodging coffin corner 😬, managing systems, and staying ready for surprises (like that engine failure at FL400 🔧).
This quick guide packs pro tips and smart strategies to help you stay sharp, save fuel, and keep things smooth up high. Because at 38,000 feet, “just cruising” still takes work. 💼🧠
General Cruise Tips
- – Set TCAS to below and increase the weather radar gain.
- – PM makes sure the wind is inserted.
- – If flying over a mountain for some period, the cabin crew should be informed that in case of loss of pressurization, it may take up to such time to expect a call that it’s safe to remove the mask.
- – Don’t climb to an altitude where you have less than a 30 kts speed margin between minimum and maximum speed.
- – Avoid reducing the throttle to idle.
Updating Cruise Winds
The winds provided to the FMC through ACARS uplink are updated every 6 hours. The updates take place at 0600z, 1200z, 1800z, and 2400z. Note that you can pre-select the levels in the LEGS page at which you wish to receive the winds. This is best done by deleting ALL the existing levels in the LEGS RTE DATA Waypoint WINDS page in the FMC, replacing them with your own (nil wind will show, and these levels will propagate forwards and backwards through the FMC LEGS waypoints), executing the modification, and then requesting new winds. The uplinked winds will be appropriate to the entered levels. You might want to do a route copy before deleting all the winds out of the FMC, just in case the new ones don’t come down.
Exceeding VMO speed
Turbulence at high altitude or certain atmospheric conditions, temperature inversion, wind direction, and speed change can cause an increase in Mach number, which can lead to exceeding VMO speed.
Autothrottle is programmed not to retard the thrust lever fast enough at cruise (slow reaction) because of the high stall speed.
The best solution in this case, when speed increases, is to manually reduce the thrust level 2 or 3 inches and hold, letting it go after 1 or 2 seconds. Do not over-decrease the speed, as it might take some time to gain it back.
🛩️ Boeing 787 Engine Failure in Cruise
1. Scenario Framing
Cruise engine failures are rare but high-consequence events, particularly over oceanic/remote airspace, in ETOPS operations, or when terrain constrains drift-down. In the 787, automation, robust alerting, and envelope protections help—but performance margins, fuel strategy, and communications become critical decision drivers.
2. Recognition & Confirmation
- – EICAS alerts/messages (e.g., ENG FAIL, ENG SHUTDOWN, ENG THRUST (L/R), ENG STALL indications depending on failure mode).
- – Thrust asymmetry felt as yaw; rudder input or TAC (Thrust Asymmetry Compensation) response.
- – Engine parameter decay (N1, N2, EGT, fuel flow).
- – Autothrottle split or large thrust lever mismatch.
Confirm before action: Verify which engine. Confirm indications on both Primary Engine Displays and EICAS. Use standard callouts (“Engine Failure – Left/Right Confirmed”).
3. Immediate Priorities (Big Three)
Aviate
- – Maintain attitude and flight path. Autopilot normally remains engaged; allow it to stabilize unless malfunctions.
- – Monitor airspeed and bank; engine-out yaw may induce roll if uncorrected.
Navigate
- – Start thinking drift-down: Are you able to maintain current FL? Likely not at heavy weight/high altitude.
- – Select engine-out cruise altitude (single-engine ceiling) via FMC ENG OUT function or QRH guidance.
- – Consider turn toward drift-down track / nearest suitable airport / ETOPS alternate depending on location.
Communicate
- – ATC: “MAYDAY” or “PAN PAN” per company SOP & severity.
- – Advise engine failure, unable maintain FL (if applicable), request lower altitude and routing to selected airport or continue as briefed if performance permits.
- – Company/dispatch via ACARS/CPDLC when workload permits.
4. Checklist Integration
On the 787, EICAS-driven Non-Normal Checklists (NNCs) guide the response. Flow:
- Silence/acknowledge alert as per SOP.
- Perform any memory items only if the condition demands (e.g., Engine Fire/Severe Damage/Separation requires memory items; a simple flameout does not).
- Open and action the displayed NNC (e.g., ENG FAIL/SHUTDOWN).
- If restart is appropriate/possible, follow engine relight procedures (windmill or starter-assisted depending on conditions).
- If restart not possible or not attempted, secure the engine per checklist.
Training note: Emphasize discipline: “Follow the box.” Do not leap ahead unless memory items required.
5. Performance & Flight Path Management
Drift-Down Concept
After losing thrust on one engine at cruise altitude, aircraft likely cannot maintain current level. A drift-down is initiated to descend along an optimized profile to a level where the remaining engine can sustain cruise.
- – Use FMC ENG OUT (if modeled/enabled in sim) to compute drift-down altitude and speed.
- – If FMC not immediately used, pitch for engine-out long-range speed from QRH tables.
- – Respect obstacle clearance: If in a terrain environment (e.g., Himalayas), drift-down routing matters.
Engine-Out Cruise Altitude
- – Determined by weight, temperature, and remaining engine performance.
- – Gradually improves as fuel burns off; step climbs may later be possible.
Buffet / Coffin Corner Tie-In
You may already be high (near MAX ALT) when the failure occurs—margin collapses quickly. Initiate drift-down promptly to avoid coffin-corner compression of stall/overspeed margins.
6. Speed Strategy
Typical guidance (always defer to QRH/company SOP):
- – Target engine-out drift-down speed initially.
- – Once level at single-engine cruise, set LRC Engine-Out or company-specified Mach/IAS.
- – Avoid overspeed: reduced thrust margin means slower acceleration control.
- – Turbulence? Use turbulence penetration speed (Mach or IAS) if higher priority for structural limits.
Q & A
Q1: What is the difference between Optimum and Maximum Altitude on the CRZ page?
- A:
- – Optimum Altitude: Based on aircraft weight for best fuel efficiency.
- – Maximum Altitude: Defined by thrust or buffet limits; do not exceed.
Q2: What does the FMC use to calculate a step climb?
- A:
- Aircraft weight, temperature, winds, and cost index. The FMC will suggest a step climb when it’s fuel-efficient and within performance margins.
Q3: What should you do if there is a discrepancy between the actual and planned fuel burn?
- A:
- 1- Investigate possible causes:
- – Incorrect flight level.
- – Unexpected headwinds.
- – Anti-ice usage.
- – APU operation.
- – Fuel leak (cross-check tanks).
- 2- Use the FUEL PRED and PROG pages to evaluate trends.
- 1- Investigate possible causes:
Q4: How do you monitor position accuracy during cruise?
- A:
- Confirm FMC position matches raw data (e.g., VOR/DME).
- Monitor ANP (Actual Navigation Performance) vs RNP.
- Check for IRS drift or GPS updating.
Q5: What should you do during turbulence in cruise?
- A:
- – Reduce Mach (e.g., from .85 to .83).
- – Turn on seatbelt sign.
- – Communicate with ATC for altitude change if required.
- – Avoid large inputs—autopilot should remain engaged unless malfunctioning.
Q6: What do you consider when planning a drift-down after engine failure?
- A:
- – Use QRH/QRH checklist.
- – FMC provides drift-down profile and engine-out ceiling.
- – Divert to nearest suitable airport if outside ETOPS envelope.
Q7: What should you do if the EICAS shows a gradual fuel imbalance?
- A:
- – Confirm if it’s within tolerance (787 manages this well).
- – Consider crossfeed operation if QRH instructs.
- – Ensure the cause is understood (e.g., one engine burning more).
Q8: What are your actions if the SATCOM or CPDLC fails over oceanic airspace?
- A:
- – Use HF or VHF as backup.
- – Attempt to contact ARINC or ATC via alternate methods.
- – Advise of SELCAL inoperative if applicable.
- – Use ICAO procedures for loss of comms if fully out of contact.