|CHAPTER 3. Navigation
Figure 3-53 shows three common course reversals: (1) 45-degree procedure turn, (2) holding pattern, and (3) teardrop procedure.
Course reversals are handled in the same way as holding procedures, by using the FMS/GPSís nonsequencing mode. As you arrive at the initial approach waypoint, the unitís nonsequencing mode should be engaged to prevent it from immediately sequencing to the next waypoint in the approach. After completing the course reversal, be sure to re-engage the systemís sequencing mode to continue the approach.
The navigation unit in Figure 3-54 requires that you manually switch between the sequencing and nonsequencing modes.
Preprogrammed Course Reversals
Some FMS/GPS units insert preprogrammed course reversals into published instrument approach procedures. The purpose of a preprogrammed course reversal is to relieve you from the mode switching and course selection tasks associated with course reversals.
The FMS/GPS unit in Figure 3-55 includes a preprogrammed course reversal. This unit automatically sets the outbound course for the outbound portion of the course reversal. Once the turn inbound has been made, the unit automatically sets the inbound course back to the final approach waypoint.
This FMS/GPS unit does not switch between sequencing and nonsequencing modes for a 45-degree course reversal (although it does for a holding-type course reversal). Whether it is done manually, automatically, or not at all, you must be sure that the system is engaged in sequencing mode before reaching the final approach waypoint after the course reversal is completed. The FMS/GPS will switch to the approach mode only if the system is engaged in the sequencing mode.
Common Error: Mismanaging the Sequencing/ Nonsequencing Modes During a Course Reversal
Neglecting to switch the FMS/GPS from the nonsequencing mode prior to reaching the initial approach waypoint and neglecting to switch the system back to the sequencing mode prior to passing the final approach waypoint are common errors made during course reversals.
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