Step Climb Mid-Cruise

Step-by-step: Step Climb Mid-Cruise

1. Set up the long-haul cruise. Type EGLL/KJFK and press 1R to enter your route.

   Eastbound and westbound transatlantic flights typically step climb 1-2 times during the cruise. As fuel burns off, the aircraft's optimum altitude rises — flying at the optimum saves fuel directly. The OFP usually pre-plans these step climbs, but you have to execute them by changing CRZ FL when ATC clears the new level.

2. Set the flight number BAW117. Type BAW117 and press 3L.
3. Set initial cruise level FL340. Type 340 and press 6L.

   Semi-circular rules: westbound (track 180-359°) uses even levels, eastbound (000-179°) uses odd. Heavy aircraft can't reach their optimum altitude immediately — at takeoff weight, FL340 may be the highest practical level. As fuel burns the optimum rises by ~1,000-2,000 ft per hour of cruise.

4. Two hours into the cruise, you've burned enough fuel to step up. Open the PROG page to see the recommended maximum altitude.

   PROG is the in-flight situational page. The REC MAX value (here shown as FL398) is the absolute ceiling for the current weight. OPTimum is usually 2,000-4,000 ft below REC MAX. You always step up to a level below REC MAX to leave margin for turbulence and weight uncertainty.

5. Return to the INIT page to update the cruise level.
6. Step up to FL360. Type 360 and press 6L to update CRZ FL.

   After updating CRZ FL the FMS recalculates the rest of the cruise at the new altitude. Real Airbus pilots cross-check the new fuel prediction against the OFP step-climb plan before accepting. If predicted arrival fuel is below reserves, you don't step up — even if ATC offers it.