Section 4 – Normal procedures
ADDITIONAL GUIDANCE FOR RNAV GPS
AFMS N°D07 FOR GARMIN GFC700 AUTOPILOT AND VARIABLE PITCH PROPELLER EQUIPPED
AEROPLANES
NOTE: The instrument approach procedures associated with RNP APCH are entitled
RNAV (GNSS) to reflect that GNSS is the primary navigation system. With the inherent
onboard performance monitoring and alerting provided by GNSS, the navigation specifica-
tion qualifies as RNP, however these procedures pre-date PBN, so the chart name has re-
mained as RNAV.
Missed approach procedures
Before commencing an RNAV (GNSS) missed approach, a MAP should be possible with-
out reference to GPS derived navigation so that, in the event of a loss of GPS accuracy or
loss of integrity during the approach, a safe return to above Minimum Sector Altitude can be
made.
This may be possible by dead reckoning (DR) navigation but where this is not possible
and the MAP requires reference to terrestrial navigation aids, these must be available,
tuned and correctly identified before passing the IAF and remain available throughout
the approach.
Reasons for a missed approach are many and if GPS information remains available for the
MAP, the pilot must be able to sequence the system correctly past the MAP, in order to
follow the published MAP correctly.
Pilots should be fully competent in the necessary selection routines required by their own
equipment, in order to transition to the MAP and preserve accurate navigation throughout.
When GPS navigation is NOT available for the MAP, it may be necessary to reset the dis-
play function of the HSI/CDI to disengage GPS information and regain VOR/LOC display.
Pilots must be fully conversant with navigation display selections in order safely to follow
the MAP.
Abnormal procedures for approaches
As the aircraft approaches the FAF (LNAV Only, without SBAS), the receiver automatically
perform a final RAIM prediction for the approach. The receiver will not enter the ap-
proach mode if this RAIM prediction is negative. In this case, the approach should be dis-
continued.
However, this RAIM check assumes availability of the full constellation and will not take
account of scheduled interruptions or failures. This can lead to a successful RAIM prediction
at this point when the RAIM function itself is not available.
If RAIM is lost after passing the FAF the equipment should continue to provide naviga-
tion, where possible for five minutes, before giving a RAIM loss indication and this should
be enough to complete the approach.
Should RAIM detect an out of tolerance situation, a warning will be given and a missed
approach should be initiated immediately
To Next Page
Loading...
