Part C: Secondary surveillance radar transponder additional surveillance data capability referred to in Article 4(3), point (c) of Article 5(5), Article 7(2), Article 8(2) and (3) and Article 14(1)

1. Each transponder register that is implemented shall be compliant with the corresponding section of ICAO document 9871 (2nd edition).

2. The following data items, where available on a digital bus, shall be transmitted by the transponder as requested by the ground-based surveillance chain, via the Mode S protocol and in accordance with the formats specified in ICAO document 9871 (2nd edition):

(a)  MCP/FCU selected altitude;

(b)  roll angle;

(c)  true track angle;

(d)  ground speed;

(e)  magnetic heading;

(f)  indicated airspeed (IAS) or mach number;

(g)  vertical rate (barometric or baro-inertial);

(h)  barometric pressure setting (minus 800 hectoPascals);

(i)  track angle rate or true airspeed if track angle rate is not available.

3. Other data items may be made available to the transponder.

4. The data items referred to in point 3 shall only be transmitted by the transponder via the Mode S protocol. The aircraft and equipment certification process shall cover the transmission of these data items.