Performance Based Navigation

PBN stands for Performance Based Navigation and is defined as “area navigation based on performance requirements for aircraft operating along an ATS route or on an instrument approach procedure or in a designated airspace."
It represents a shift from ground-based navigation aids to satellite-based systems like GPS and its augmentations.
PBN offers benefits such as more direct routes, reduced fuel consumption, and improved airspace efficiency.

RNAV (Area Navigation): Allows aircraft to fly on any desired path within the coverage of ground or space-based navigation aids.
RNP (Required Navigation Performance): A more precise form of RNAV with onboard performance monitoring and alerting to ensure the aircraft stays within specified accuracy limits.
Navigation Specifications: Define the accuracy required for different phases of flight, such as RNAV 1, RNAV 2, RNP 1, RNP APCH, etc. The manual details the specific requirements for each specification.
GNSS (Global Navigation Satellite System): Encompasses various satellite navigation systems, including GPS, GLONASS, Galileo, and BeiDou.
Augmentation Systems: Enhance the accuracy and integrity of GNSS signals. Examples include:
SBAS (Satellite-Based Augmentation System): EGNOS in Europe, WAAS in the USA, MSAS in Japan, and GAGAN in India.
GBAS (Ground-Based Augmentation System): Provides highly accurate and localized corrections.
ABAS (Aircraft-Based Augmentation System): Includes RAIM (Receiver Autonomous Integrity Monitoring) and AAIM (Aircraft Autonomous Integrity Monitoring).

TSO-C129 (non-SBAS): Uses only GPS signals and can only fly LNAV approaches.
TSO-C146 (SBAS): Receives correction signals for improved accuracy and enables more precise approaches like LNAV/VNAV and LPV.

A critical safety feature for non-SBAS receivers that uses redundant satellite measurements to detect and exclude faulty signals, ensuring navigation data integrity.
Requires a minimum of five satellites for fault detection and six for fault detection and exclusion.
Pilots should perform pre-flight RAIM predictions to assess availability. Tools like Augur and the GNSS Navigator can assist with this.

Provides superior accuracy and integrity compared to non-SBAS systems.
Enables 3D approaches like LPV with lower decision altitudes.
Offers faster error detection (within 6 seconds) in case of GPS malfunctions.

Pilots need a current Instrument Rating or BIR (Basic Instrument Rating) to fly PBN procedures in Europe.
Aircraft must be equipped with approved GNSS receivers and meet the requirements outlined in the AFM (Aircraft Flight Manual).
Pilots must be familiar with their specific GNSS receiver, its operation, and its limitations.

FPL Equipment Codes: Indicate aircraft PBN capabilities in flight plans (e.g., B2 for GNSS RNAV 5).
AIRAC Cycle: Navigation database updates occur on a monthly cycle. Pilots must ensure they use current data.
CNFs (Computer Navigation Fixes): Used by the GNSS receiver for navigation but not recognized by ATC.
Database Overlay Procedures: Many SIDs, STARs, and approaches are overlaid with RNAV waypoints and CNFs. Pilots should be aware of the differences between database-coded and charted procedures.
CDI Sensitivities: The CDI scale adjusts automatically to the active phase of flight. Understanding these sensitivities is crucial for accurate navigation.

Specific procedures designed for RNP operations, providing enhanced accuracy and obstacle clearance.
Include different minima based on available navigation capabilities (LNAV, LNAV/VNAV, LPV).
Pilots should familiarize themselves with the specific operating procedures for RNP approaches, including missed approach procedures.

Pre-flight Checks: Include GNSS receiver self-test, RAIM prediction (if applicable), and verification of user settings.
Gross Error Checks: Essential throughout the flight, particularly when approaching the IAF and during the approach phase.
Situational Awareness: Maintaining awareness of aircraft position, CDI sensitivities, and active navigation modes is critical.
Loss of RAIM/SBAS: Pilots need to understand the procedures and communicate appropriately with ATC in case of integrity warnings or system failures.
Quotes from the Source:

"Performance based navigation is area navigation based on performance requirements for aircraft operating along an ATS route or on an instrument approach procedure or in a designated airspace.” (PBN Concept)
"The receiver can recognise that a satellite is faulty, because the 5 range spheres don’t all intersect at a consistent point." (ABAS: RAIM Fault Detection and Exclusion)
"SBAS provides a more accurate method of error checking. Integrity and safety are improved by alerting SBAS users within 6 seconds if a GPS malfunction occurs." (GNSS Augmentation)
"If alert limits are exceeded, LPV will degrade to LNAV using RAIM, at which point LNAV minima apply, and if RAIM is lost, an integrity warning is annunciated and a missed approach commenced." (RNP APCH Operating Procedures)
"Following a RAIM or Integrity indication, pilots shall inform the controller of the event and subsequent intentions." (ATC Procedures)
This briefing provides an overview of the key points addressed in the PBN Manual. It is essential for pilots to study the complete manual thoroughly to gain a comprehensive understanding of PBN and GNSS operations and to ensure safe and efficient IFR flight.