IFD500 Series Pilot Guide
Navigation 6-27
When GPS has been selected as the nav source, and one of the
RNAV/GPS approach types with vertical guidance (LPV, L/VNAV,
LNAV+V, LP+V) is selected in the FMS, the IFD will transmit
horizontal and vertical deviation for use by any integrated external
display device.
There are several types of SBAS approaches. The FMS will
automatically select the best available approach based on current
GPS integrity and will indicate the selection in the Nav Mode
datablock field.
TIPS AND TECHNIQUES
Nav Mode Datablock
The Nav Mode datablock (see page 5-48) indicates
the current navigation mode (e.g. Enroute, Terminal,
Approach). Instead of showing “Approach”,
however, the datablock shows the approach type
(e.g. LNAV, LPV, LNAV+V).
The pilot must monitor the IFD throughout the approach and use
charted minimums appropriate to the approach type. If an
approach type is not indicated by the time the final approach fix
(FAF) is reached, do not descend – the conditions required to fly
the approach have not been met and you must fly the missed
approach procedure.
SBAS approach types in the Nav Mode datablock and the nav
source indication in the top right corner of the display include:
LNAV (Lateral Navigation)
An LNAV approach provides lateral (horizontal) guidance
only, with standard GPS precision of 0.3 NM full-scale
deflection. This is essentially the same as a non-SBAS GPS
approach. It is flown as any other non-precision approach –
observing step down restrictions, descend to MDA, fly at
MDA altitude to the missed approach point (MAP); and
execute the missed approach procedure if appropriate.
Since there is no vertical guidance associated with this type
of approach, the IFD will not transmit any vertical deviation
information. The Nav Mode datablock will display “LNAV”
for the approach type.
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