Learn how to enable PMDG step climbs in MSFS, read STEP TO predictions, initiate the climb with VNAV and fix missing S/C points.
In PMDG Boeing aircraft for Microsoft Flight Simulator, enter a non-zero STEP SIZE in the FMC, check the predicted STEP TO altitude and S/C point, obtain clearance, then set the higher MCP altitude. Let VNAV climb at the planned point or use the type’s altitude-intervention control to initiate it.
How do I enable step-climb predictions?
Step-climb predictions are enabled by setting a valid step size after completing the route and performance data. The FMC uses aircraft weight, winds, cost index and cruise altitude to calculate when a higher level becomes economical.
- Complete the route and PERF INIT data. Activate the route and enter valid weight, fuel or reserves, cost index and initial cruise altitude. Missing or incorrect weight data makes the calculated optimum, maximum and step altitudes unreliable. Our guide to configuring an airliner FMC and its performance data covers the underlying sequence.
- Find the STEP SIZE field. Its position varies between the PMDG 737 and long-haul Boeing FMC layouts, so check the
PERF INITandCRZpages. EnterICAOor a numerical increment accepted by that FMC. - Execute any modification. Press
EXECif the CDU presents the entry as a route or performance modification. - Inspect the prediction. Look for
STEP TOinformation on the cruise page and anS/Cpoint on the route, LEGS or navigation display. The precise combination of labels differs by aircraft.
| STEP SIZE entry | What it does | When to use it |
|---|---|---|
ICAO | Uses the FMC’s standard ICAO step schedule. | Choose this for normal directionally appropriate cruise-level planning. |
| Numerical increment | Plans fixed altitude increases, such as the interval specified by an operational flight plan. | Choose this when a dispatch plan or operating procedure specifies the step interval. |
0 | Inhibits automatic step-climb predictions. | Choose this when remaining at one cruise level or managing every climb manually. |
To change the schedule, overwrite STEP SIZE; to cancel it, enter 0 where supported. The S/C marker is computed rather than a normal waypoint, so it can move as fuel burns or forecast winds change.
How do I initiate the climb at the S/C point?
A planned S/C becomes a real climb only when the MCP altitude and VNAV logic permit it. The FMC prediction is not an ATC clearance.
- Obtain clearance. Confirm that the higher level is permitted by ATC, direction-of-flight rules and local airspace. Microsoft Flight Simulator ATC does not automatically exchange step-climb plans with the PMDG FMC.
- Check the target level. Select a level close to
OPTand comfortably belowMAX. Higher is not automatically better when strong winds, temperature or a nearby top of descent make the climb uneconomical. - Set the MCP altitude. Shortly before the calculated point, turn the altitude selector to the cleared step altitude. Do not set a level above the FMC’s maximum altitude merely because ATC offers it.
- Authorise the climb. Depending on the PMDG aircraft and FMC state, VNAV may command the climb when the aircraft reaches
S/Cand the MCP allows it. To initiate an immediate or early cruise climb, useALT INTVon the 737 or the equivalent altitude-selector push function on types fitted with it. - Read the FMA. Confirm that the aircraft leaves altitude hold and displays active climb thrust and pitch guidance. The exact mode names differ by Boeing type; the Flight Mode Annunciator, not the CDU prediction, proves what the autopilot is doing. Our PMDG 737 MCP, VNAV and FMA walkthrough explains these indications in detail.
- Verify the new cruise level. After levelling off, check that the cruise page reflects the new altitude and has rebuilt its fuel and top-of-descent predictions.
A mistake we see constantly is replacing the original CRZ ALT with the future step altitude too early. That can turn the plan into an immediate cruise climb or recalculate the intended S/C point. Leave the initial cruise altitude in place while using the step schedule unless you deliberately want to climb now.
Why is the PMDG S/C point missing?
A missing step-climb point usually means the FMC cannot calculate a useful or valid climb before descent begins.
STEP SIZEis set to0, blank or an invalid value.- The route has not been activated or executed, or there is an unresolved discontinuity ahead.
- Weight, cost index, initial cruise altitude or other performance data are incomplete.
- The flight is too short, so the economical step point falls after the top of descent.
- The proposed altitude exceeds
MAXat the aircraft’s present weight and temperature. - The marker is farther along the route than the selected navigation-display range shows.
- A direct-to, route change, new wind entry or early descent has forced the FMC to recalculate or remove the point.
Do not force the marker to appear by entering an implausibly high cruise level. Correct the route and performance data, then let the FMC recalculate.
What if VNAV will not start the step climb?
VNAV will not climb unless the selected MCP altitude is above the aircraft and the active mode permits a climb.
- Check that the MCP still contains the cleared higher altitude rather than the present cruise level.
- Confirm VNAV is engaged and the FMA is not simply holding altitude in another mode.
- Review the CDU for messages, route discontinuities or an altitude target above
MAX. - Make sure the aircraft has not entered its descent phase or passed close enough to the top of descent for the step to be discarded.
- Check for an altitude constraint before using altitude intervention; that control can remove constraints in other phases of flight.
If VNAV remains unsuitable after clearance, use LVL CHG on the 737 or FLCH on the applicable Boeing type, select an appropriate speed and monitor thrust closely. After levelling off, enter or confirm the new cruise altitude in the FMC so its fuel and descent calculations match the aircraft’s actual level.