BY ORDER OF THE SECRETARY OF THE AIR FORCE AIR FORCE ...

132
AFMAN 11-217V1 3 JANUARY 2005
7.12.2.6.3.1. RAIM Alerts. There are two types of RAIM alerts. One type
indicates that not enough satellites are in view (or in an insufficient geometry)
to provide RAIM. The other type indicates that the RAIM monitor has
detected a potential error that exceeds the limits (enroute, terminal, or
approach) for the current phase of flight. Without RAIM capability, the pilot
has no assurance of GPS positional accuracy.
7.12.2.6.3.2. Predictive RAIM. This is the process where the GPS receiver
predicts whether RAIM will be available at a particular location at a time in
the future. To effectively check predictive RAIM, aircraft avionics must
allow deselection of satellites based on NOTAM information. Predictive
RAIM must be checked prior to flight or flight segment where GPS is
required.
7.12.2.6.3.2.1. The requirement for a predictive RAIM check only applies
to those aircraft that are not approved for RNP RNAV operations as
indicated by appropriate statements in the aircraft flight manual. Prior to
flying RNP RNAV procedures, aircrew must ensure that the appropriate
level of RNP will be available to fly a given procedure. This may or may
not require a predictive RAIM check. Details on methods to confirm RNP
RNAV availability are detailed in the aircraft flight manual.
7.12.2.6.3.2.2. If the required level of RAIM (e.g., enroute, terminal or
approach) is not available, another type of navigation and approach
system must be used, another destination selected, or the trip delayed
until RAIM is predicted to be available.
7.12.2.6.3.2.3. Pilots should recheck the RAIM prediction for the
destination during the flight. This may provide early indications that an
unscheduled satellite outage has occurred since takeoff.
7.12.2.6.3.2.4. The predictive RAIM check must be accomplished prior
to the intended GPS operation, including both GPS departures and
approaches, and may be accomplished either by onboard GPS
equipment or via a ground system. The predictive RAIM algorithm
should take into account satellites that are NOTAMed out of service
between the time of the predictive RAIM check and the flight segment
over which GPS is required. Prior to deselecting satellites for predictive
RAIM purposes, aircrew should ensure that deselecting would also affect
use of the satellite in the active navigation solution. Some systems only
allow deselecting from the active navigation solution and do not allow
deselecting for predictive RAIM purposes.
7.12.2.6.3.2.5. GPS NOTAMs may be obtained by typing "KGPS" from
the military NOTAM website. Note that the NOTAM web site refers to
satellites using the PRN, not the SVN. Most, if not all, GPS avionics use
the PRN to identify satellites to be deselected. For information on the
correlation between a particular PRN and SVN, consult the GPS Support
Center web site.