Aircraft Operations

Part II — Section 3, Chapter 1
II-3-1-9
1.7.3 Stepdown fixes
1.7.3.1 A stepdown fix is flown in the same manner as a ground-based approach. Any required stepdown fixes
prior to the missed approach waypoint will be identified by along-track distances.
1.7.3.2 Where the FMC includes a vertical navigation capability, the navigation database procedure may contain a
continuous descent flight path that remains above the stepdown procedure vertical profile. Use of FMC vertical
navigation capability will be subject to flight crew familiarity, training and any other requirements of the operational
approval.
1.7.4 Descent gradient/angle
The optimum descent gradient/angle is 5.2 per cent/3°, however where a higher gradient/angle is necessary, the
maximum permissible is 6.5 per cent/3.7°. The descent gradient/angle is published.
1.8 MISSED APPROACH SEGMENT
1.8.1 CDI sensitivity
1.8.1.1 For basic GNSS receivers, sequencing of the guidance past the MAPt activates transition of the CDI
sensitivity and RAIM alert limit to terminal mode (1.9 km (1.0 NM)).
1.8.1.2 While these criteria may apply, some FMCs may incorporate different display sensitivities for missed
approach operations. These different display sensitivities may be used when there is guidance provided by flight
director cues or autopilot. Regardless of the missed approach display sensitivity differences with the FMC GNSS
implementations, equivalent integrity of the operation must still be provided.
1.8.2 A GNSS missed approach requires pilot action to sequence the basic GNSS receiver past the MAPt to the
missed approach portion of the procedure. The pilot must be thoroughly familiar with the activation procedure for the
particular basic GNSS avionics implementations installed in the aircraft and must initiate appropriate action after the
MAPt.
1.8.3 Activating the missed approach prior to the MAPt will cause CDI sensitivity to immediately change to
terminal (±1.0 NM sensitivity), and navigation guidance will continue to the MAPt. The guidance will not be provided
beyond MAPt or initiate a missed approach turn without pilot action.
1.8.4 If the missed approach is not activated, the basic GNSS avionics implementation will display an extension
of the inbound final course and the along-track distance will increase from the MAPt until it is manually sequenced
after crossing the MAPt.
1.8.5 These criteria generally apply to FMCs. There will, however, also be installations, especially those using
navigation information on the moving map display, where the FMC path guidance will be continuously displayed for
the missed approach.
1.8.6 For the basic GNSS receiver, missed approach routings in which the first track is via a specified course
rather than “direct to” the next waypoint requires additional action by the pilot to set the course. Being familiar with all
of the inputs required is especially critical during this phase of flight.
1.8.7 The missed approach tracks are typically included in the FMC’s navigation database, such that no pilot
action is required.
23/11/06