RNP

1
PPOS Present Position
RNP Required Navigation Performance (green
shaded area indicates acceptable performance)
ANP Actual Navigation Performance
In this example, outer circle radius is the RNP,
which indicates MINIMUM acceptable system
accuracy. In other words, the navigation system
MUST be able to supply a present position with an
accurate to the area INSIDE this circle.
In this example, the inner circle radius is the
ANP, which indicates ACTUAL system accuracy. This
means that the ACTUAL Present Position is
somewhere inside this circle.
RNP
The Flight Management System calculates ANP based
on

• Available navigation sources, such as VOR,
  GPS/GNS, DME and IRS. For example, if GPS is
  lost, ANP is significantly reduced.

ANP
x
Push ENTER to Continue
Push ENTER to Continue
Push ENTER to Continue
Push ENTER to Continue
Push ENTER to Continue

• Geometry (distance and bearing) to navigation
  sources (GPS satellites, VOR or DME stations).

PPOS
A lower number for ANP indicates GOOD system
accuracy. A higher number indicates REDUCED
accuracy. This example shows GOOD ANP, because
the ACTUAL system accuracy is WITHIN the Required
limits)
2
Provided courtesy of FlightSafetyBoeing CLICK
HERE FOR MORE INFORMATION
This example shows BAD ANP (OUTER circle),
because ANP gt RNP

• ACTUAL system accuracy

ANP
NOT within Required limits
Present Position is only accurate to the within
the radius of the ANP. If ANP exceeds RNP a
message of UNABLE RNP is usually displayed.
This does not indicate that the position is
incorrect. It merely indicates that FMS cannot
guarantee accuracy of Present Position within
Required limits.
RNP
x
Push ENTER to Continue
Push ENTER to Continue
Push ENTER to Continue
PPOS
This is calculated based on quality and
availability of data being used by FMS. Accuracy
degradation can come from many factors (signal
geometry, or failed systems, etc.)