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    Phenom 300 FOL 108 : G3000 transition from VNAV PATH to GS/GP

    Embraer just posted Phenom 300 Flight Operations Letter rev 108, which includes a new G3000 transition from VNAV PATH to GS/GP memo.

    DESCRIPTION

    This FOL contains information about the Transition to Approach FMS feature introduced on G3000 avionics load version 3305.00. This feature enables automatic transition from VNAV PATH mode to Glideslope (GS) or Glidepath (GP) modes during approach.

    Embraer has received reports in which the airplane is experiencing climb or descent rates higher than expected during the transition from VNAV to GS/GP.

    With the Transition to Approach FMS feature engaged, the system is configured to transition from VNAV to GS/GP when the airplane is within a range of 200ft above or below the defined GS/GP threshold (see FIGURE 1).

    In specific conditions in which the VNAV path is steep or shallow compared to the GS/GP path angle, the aircraft may provide a more significant pitch down or pitch up to perform the capture.

    The VNAV path angle between the FAF and the waypoint just before the FAF can indicate the expected behavior of the AP/FD during the transition to GS/GP. A shallow VNAV path angle can result in a pitch up during the transition, while a steep VNAV path angle can result in a pitch down command during the transition.

    RECOMMENDATION

    If the pilot intends to use the Transition to Approach FMS feature, it is recommended to check that the VNAV path before the FAF in the FMS is close to 3 o in order to minimize the chance of experiencing the VNAVto-GS/GP transition behavior described above.

    In addition, the aircraft will not experience the VNAV-to-GS/GP transition behavior if the approach is performed using another vertical mode (VS for example).

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