SPEED LIMITS AND WAYPOINT SPEED CONSTRAINTS
A speed limit associated with an altitude threshold and a speed constraint associated with a waypoint are different programming objects. The source describes separate climb/descent applications and a specific cruise limitation: entering a waypoint speed constraint in the cruise segment does not by itself command managed cruise speed to that value. Read the field, applicable segment and active speed mode together. [66, PDF pp. 391-398]
1. Open VERT REV at the intended fix. Read whether CLB or DES context applies. For a limit, inspect the speed/altitude pair; for a waypoint restriction, inspect SPD CSTR. Do not copy a common 250/FL100 example as the rule for every airspace or flight. Use the actual chart/clearance requirement and the units and phase accepted by the page. [66, PDF pp. 391-398]
2. Enter the precise restriction. The guide accepts a calibrated-airspeed value for SPD CSTR. A climb constraint applies to the relevant segment towards the revise point; descent application has its own downpath logic. Inspect the resulting TMPY values across the affected legs. An entry beside one fix can influence more than the speed predicted at that single row. [66, PDF pp. 391-398]
3. Read the predicted compliance. Inspect the constraint and predicted speed separately, using the VERT REV and ND constraint presentation where helpful. The source distinguishes matched and missed predictions with markers/colour. Those indications express the model's current result; they do not provide clearance to exceed a restriction. If it is predicted missed, examine distance, mode, existing limits and configuration before committing. [66, PDF pp. 391-398]
4. Handle a cruise restriction explicitly. In the documented standard a cruise waypoint constraint can appear as a reference while selected speed is needed to comply in cruise. It can also affect a subsequent descent according to phase/segment logic. Do not infer compliance merely from seeing the restriction printed on the map. Check actual speed guidance and remove an obsolete cruise-only constraint when its continued effect would be unintended. [66, PDF pp. 391-398]
5. Revise or delete the right object. Use the dedicated SPD CSTR or limit field instead of an indiscriminate CLR on the combined F-PLN vertical-data row. The latter can remove additional restrictions. Insert the intended revision, then inspect the active speed mode, target and next constrained segment. Retain the current clearance reference so a display cleanup does not quietly remove a restriction that still applies operationally. [66, PDF pp. 391-398]