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The approach condition
it is only mentioned once in the document.
B777-300ER
Approach
The FMC transitions to "on approach" mode for any of the following conditions:
• the descent phase is active and flaps are out of up, or
• the airplane has sequenced the first waypoint (or FAXXX) of the active approach, or
• the airplane is on a direct-to or intercept course-to the active waypoint and the distance to go is less than 12 NM, or
• the missed approach point is the active waypoint and the distance to go is less than 25 NM
The approach condition may be delayed if the flight crew manually inserts, bypasses, or deletes an approach waypoint on the LEGS page.
The FMC transitions out of "on approach" under the following conditions:
• the pilot selects TO/GA
• the airplane lands
• the airplane flies beyond the last waypoint in the approach (missed
approach waypoint or runway). The VNAV page title changes from "ACT xxxxx DES" to "ACT END OF DES"
When the FMC is “on approach”, the following features are available:
• the IAS/MACH window can be opened and the command speed can be set while VNAV remains in VNAV PTH descent; VNAV commands the set speed
• the MCP altitude can be set above the airplane altitude for the missed approach. When the MCP altitude setting is at least 300 feet above the current airplane altitude, VNAV continues to command a descent
• VNAV remains in VNAV PTH and follows the descent path unless the airplane accelerates to within 5 knots of the current flap placard and the airplane rises more than 150 feet above the path. In this case, VNAV PTH changes to VNAV SPD
• When a glide path angle is specified for one or more legs on the approach, it displays on the LEGS page and VNAV provides VNAV PTH guidance at the displayed angle. When sequencing a waypoint prior to a descent leg specified by a glide path angle, VNAV commands level flight until the airplane intercepts the descent path
Note: Display of aspecified glidepath angle is not limited to approaches.A glide path angle may be defined for a leg in a STAR and displays on the LEGS page for the procedure.
Selection of another approach can be accomplished on the ARRIVALS page. An along-course intercept to an approach waypoint in the new approach can be selected on the “INTC CRS TO” line on the LEGS page or by selecting the "XXXXX INTC>" prompt on the ARRIVALS page.