RNP Flashcards
Required navigation performance (RNP) is a type of performance-based navigation (PBN) that allows
an aircraft to fly a specific path between two 3D-defined points in space.
RNAV and RNP systems are fundamentally similar. The key difference between them is
…………..the requirement for on-board performance monitoring and alerting.
A navigation specification that includes a requirement for on-board navigation performance monitoring and alerting is referred to AS
as an RNP specification.
RNP also refers to the level of performance required for a specific procedure or block of airspace.
The level of RNP an aircraft is capable of determines the separation required between aircraft.
An RNP of 10 means that a navigation system must be able to calculate its position to within a circle with a radius of 10 nautical miles.
An RNP of 0.3 means the aircraft navigation system must be able to calculate its position to within a circle with a radius of 3 tenths of a nautical mile.
The level of RNP an aircraft is capable of determines the
the SEPARATION required between aircraft.
The performance monitoring and alerting requirements for RNP 4, Basic-RNP 1 and RNP APCH have common terminology and application. Each of these specifications includes requirements for the following characteristics:
-The accuracy requirement defines the 95% Total System Error (TSE) for those dimensions where an accuracy requirement is specified. The accuracy requirement is harmonised with the RNAV navigation specifications and is always equal to the accuracy value. A unique aspect of the RNP navigation specifications is that the accuracy is one of the performance characteristics that is monitored-
Performance monitoring: The aircraft, or aircraft-and-pilot combination, is required to monitor the TSE, and to provide an alert if the accuracy requirement is not met or if the probability that the TSE exceeds two-times the accuracy value is larger than 10−5. To the extent operational procedures are used to satisfy this requirement, the crew procedure, equipment characteristics, and installation are evaluated for their effectiveness and equivalence
Aircraft failures: Failure of the aircraft equipment is considered within airworthiness regulations. Failures are categorised by the severity of the aircraft level effect, and the system must be designed to reduce the likelihood of the failure or mitigate its effects. Both malfunction (equipment operating but not providing appropriate output) and loss of function (equipment ceases to function) are addressed. Dual system requirements are determined based on operational continuity (e.g. oceanic and remote operations). The requirements on aircraft failure characteristics are not unique to RNP navigation specifications.
Signal-in-space failures: Signal-in-space characteristics of navigation signals are the responsibility of the ANSP.[9]
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In an aircraft utilising a stand-alone GNSS,
RNP is achieved through the use of
Receiver Autonomous Integrity Monitoring
RAIM
Area navigation systems often
integrate several sources of navigation
information e.g.
inertial and GNSS,
to provide highly accurate navigation
solutions.
These systems may use alternate means
of aircraft autonomous integrity monitoring
systems that are the equivalent of RAIM.
The on-board performance monitoring and
alerting function ensures the integrity of
the navigation solution i.e.
the system is
meeting the required accuracy.
Information from the GNSS calculates its
position from the satellites in view.
A timely warning is provided when the
accuracy of that position falls outside an
acceptable limit, alerting the pilot
of the need to discontinue the approach.
For example, setting an RNP value of
0.3 NM means the on-board performance
monitoring will alert the pilot if it estimates
the error of the navigation system
exceeds 0.3 NM
Under PBN, airspace and route design
take into account the aircraft operations
in the region, and the capability of aircraft
flying there.
Both aircraft and flight crew must meet performance standards for that route, which may change according to the flight phase (en route, approach etc.) and the class of airspace in which the aircraft is flying.
Under PBN, common Australian
operational navigation specifications
will be:
» RNP 2—en route » RNP 1—for Standard Instrument Departures (SIDs), and Standard Terminal Arrival Routes (STARs) » RNP–APCH—LNAV approach
