Figure: Communications capabilities and performance related to separation assurance, from ICAO Document 9869, Figure 3-2.

Eddie Sez:

Most pilots who have flown internationally in the last decade or so are well acquainted with the concept of Required Navigation Performance (RNP), the idea that where you can fly will be determined on how accurately you can fly and how well the system alerts you when things are less than promised. While it isn't a perfect statement, you can think that the XX in your RNP-XX relates to that accuracy. The same concept holds true for communications and surveillance. In the case of communications, the number attached to your Required Communications Performance (RCP) is the number of seconds it takes for an instruction to travel from the ground to you and your acknowledgement back to the ground. Does it matter? Yes, the lower the number the tighter the airspace you will be allowed to fly. Put another way, the higher the number, the more airspace around the world that will be denied you.

What follows are quotes from various sources, listed below, as well as my comments in blue.


History

[ICAO Doc 9869, ¶1.1.4] The fourth meeting of the Aeronautical Mobile Communications Panel (AMCP/4) (Montreal, April 1996) recognized the absence of objective criteria to evaluate communication performance requirements. This objective criteria was seen as a set of values for parameters, which would be based on the operational requirements for communication systems in the various phases of flight. The meeting agreed that there was an urgent need to assess the various technical options of communication systems against such a set values for these parameters. The term RCP type is used to denote a set of values for these parameters.

This all grew out of the initial efforts to formalize the Future Air Navigation System (FANS) that led to the development of a Required Navigation Performance (RNP) standard. It may not seem as significant as the revolutionary changes seen in navigation, but RCP is the underlying principle behind getting rid of HF and moving toward SATCOM. That also spawned the need to differentiate SATVOICE versus SATCOM.


Concept

[ICAO Doc 9869, ¶2.2]


RCP Type

[ICAO Doc 9869, ¶3.2]

This is good stuff for a comm geek but really not that pertinent to a pilot. But it helps to understand what is to follow:

Figure: Recommended RCP Types, from ICAO Document 9869, Table 3-1.

[ICAO Doc 9869, ¶3.3]

There you see the crux of the RCP issue for a pilot. If you are flying in an environment where you have 50 nm or more lateral spacing, you are probably flying in an RCP-400 environment. The turn around time from the controller to the radio operator to you and back is 400 seconds. An HF will suffice. But, on the other hand, if you are flying with only 30 nm of lateral spacing and reduced longitudinal separation, you are probably dealing with an RCP-240 environment. Now you need CPDLC. If you combine CPDLC with ADS, you can get even lower with a thing called Required Surveillance Performance (RSP):

Figure: Examples of applying RCP and RSP specifications, from ICAO GOLD, Tables 2-3 and 2-4.


Book Notes

Portions of this page can be found in the book International Flight Operations, Part IV, Chapter 1.


References

ICAO Document 9869 AN/462 (Draft), Manual on Required Communication Performance (RCP)

ICAO Global Operational Data Link Document (GOLD), International Civil Aviation Organization, Second Edition, 26 April 2013