Definition
PBN/ is the standard prefix used in the Item 18 'Other Information' field of an ICAO flight plan to indicate the aircraft's RNAV and RNP capabilities. It is followed by one or more codes (such as A1, B2, C1, D1, L1, O1, S1, T1) that identify the specific navigation specifications the aircraft is approved and equipped to fly.
Plain English
It is the label you put on a flight plan, followed by short codes, to tell ATC exactly which types of modern satellite and area navigation your aircraft can perform.
Context Anchor
Seen in instrument procedure discussions, especially RNAV departures, arrivals, approaches, and notes that describe what navigation capability is required.
Derivation
PBN stands for Performance-Based Navigation. The trailing slash is part of the ICAO flight plan formatting convention -- each indicator in Item 18 is written as a label, a slash, and then the relevant codes (for example, PBN/A1B2). The slash simply separates the label from its data.
Why Pilots Care
Allows more direct routes, lower fuel use, and access to procedures where older navigation methods would not suffice.
Intuition Check
PBN is not the name of one instrument or one GPS unit. It is a performance standard the aircraft’s navigation system must meet for that procedure.
Example Sentence 1
The crew filed PBN/A1B2C2D2L1O2S1 in Item 18 to declare their full RNAV and RNP capability for the international flight.
Example Sentence 2
Controllers cleared the flight for a PBN route that avoided congested airspace.