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When setting up an aircraft profile, selecting the correct Performance-based Navigation (PBN) codes is important. This article provides guidance on choosing the proper codes. 

Performance-Based Navigation (PBN)  is a specification for describing how accurately an aircraft can navigate. Three components define an aircraft's PBN code. 

• Crew alerting capabilities
• Sensor accuracy 
• Sensor type

Crew Alerting Capabilities

With regards to PBN alerting capabilities, there are two classifications:

• Minimum Area Navigation (RNAV) 
• Required Navigation Performance (RNP) 

RNP equipment alerts the crew when the navigation system is incapable of assuring navigational accuracy, and therefore, other means of navigation must be used, or the operation must be aborted. 

Sensor Accuracy

PBN equipment must ensure the aircraft can navigate within some maximum width at least 95% of the time. 

For example, for equipment to be certified as RNAV 2, the aircraft must be capable of remaining within 2 nm of the centerline 95% of the time. 

Sensor Types

There are multiple methods for determining an aircraft's position. RNAV equipment may rely on ground, satellite, onboard long-range systems, or a combination of all three. Each sensor type is briefly discussed below. 

• GNSS (GPS) is a satellite-based system with which most pilots are familiar. GNSS can be used for navigation over land and long-range navigation over the oceans.
• DME/DME is a sophisticated RNAV system that tunes and receives multiple DME ground stations to triangulate the aircraft's current position.
• Inertial Navigation (INS/IRU) systems are based on precise measurement of accelerations to determine speed and direction. INS systems may be used for long-range oceanic navigation.
• DME/DME/IRU is based on an Inertial Navigation sensor in combination with a DME/DME sensor. With the DME/DME sensor input, the IRU is continuously corrected for drift when suitable DME reception is available. 
• VOR/DME relies on the simultaneous reception of a colocated VOR and DME signal. The avionics computer receives the current radial and distance and calculates the course and distance to the waypoint. 
• LORAN is no longer supported. 

PBN Codes 

There are 24 codes for specifying an aircraft's PBN capabilities. A maximum of eight codes may be selected for any particular flight. 

PBN codes are specified using one letter and one number. The letter specifies the relevant RNAV or RNP performance navigation specification. The number describes either the sensor used to provide the capability or a sub-capability. 

For example, D codes apply to the RNAV 1 specification with the associated number indicating the sensor type. 

• D4 indicates the sensor is DME/IRU
• D3 indicates the sensor is DME/DME. 
• D2 indicates the sensor is GPS.
• D1 indicates the aircraft is equipped with all the sensors. 

Selecting PBN codes 

When selecting PBN codes, specify the equipment's performance specification and sensor type. When a PBN code specifies a particular sensor (e.g., GNSS), the ICAO equipment code must also specify the sensor. 

For example, D2 represents the RNAV 1 performance specification using GPS. As a result, the ICAO equipment code G must also be specified. Inconsistencies between PBN sensor type and ICAO equipment will result in the rejection of a flight plan.

The following table contains a brief explanation of the various PBN codes.