PBCS is an umbrella term for communication and surveillance specifications, comparable to the use of “PBN” as an umbrella for navigation specifications. Communication specifications are described in terms of an aircraft’s Required Communication Performance (RCP) ability (e.g., RCP240, RCP400) and surveillance specifications are described in terms of an aircraft’s Required Surveillance Performance (RSP) ability (e.g., RSP180).
In both cases, RCP and RSP, the numerical value refers to the aircraft’s performance in seconds –that is, the maximum time the equipment would take to perform the intended communication / surveillance action. A lower value means that the equipment is faster and therefore capable of more advanced functions. The value does not refer to a static performance time, but instead is an upper window; 99% of all operations must be met within that window to be RCP / RSP certified.
PBCS has been implemented to help ensure that regulators and manufacturers meet and adhere to safe standards when designing advanced communication and surveillance networks, such as CPDLC and ADS-C.