Aircraft Identification (TC 1–4)

BDS 0,8 — category set follows type code (DO-260B / ED-102A).

Emitter category Category Type code sets A–D

TC 4 uses category set A (light → heavy / rotorcraft).

Identity ICAO address 6 hex Callsign 8 chars A–Z 0–9 Capability (CA)

Position (TC 0 / 5–18)

CPR compact lat/lon. Airborne (TC 9–18, BDS 0,5) vs surface (TC 5–8, BDS 0,6) differ in ME layout and CPR zone size (360° vs 90°). Decode with a local reference (~180 NM air / ~45 NM surface) or an even/odd pair (surface pair still needs a local ref). TC 0 = no position information.

Mode & CPR scheme Position kind Type code airborne · NIC band CPR scheme Odd CPR frame local scheme only Even frame is newer pair decode UTC time synchronized (T)

Pair encode writes two Mode S hex lines (even then odd). Hex box expands to two lines.

Identity ICAO address 6 hex Capability (CA)

Aircraft / vehicle position

Latitude ° Longitude °

Airborne fields Surveillance status NIC supplement-B Barometric altitude ft 25 ft · blank = unknown

GNSS Position (TC 20–22)

Same airborne CPR layout as TC 9–18 (BDS 0,5), but altitude is GNSS geometric encoded as integer metres (UI in feet). Reuses local-reference and even/odd pair schemes. TC selects NIC band.

Type & CPR scheme Type code NIC band CPR scheme Odd CPR frame local scheme only Even frame is newer pair decode UTC time synchronized (T)

Pair encode writes two Mode S hex lines. Hex box expands to two lines.

Identity ICAO address 6 hex Capability (CA)

Aircraft position

Latitude ° Longitude °

GNSS altitude & status Surveillance status NIC supplement-B GNSS altitude ft stored as metres · max ≈ 13 440 ft

Airborne Velocity (TC 19)

BDS 0,9 — subtypes 1–2 ground speed (EW/NS); 3–4 airspeed (heading + IAS/TAS). Supersonic subtypes use 4 kn LSB.

Subtype & quality Subtype NAC_v Intent change flag

Identity ICAO address 6 hex Capability (CA)

Ground speed (subtypes 1–2) East/West velocity kn +E / −W · blank = N/A North/South velocity kn +N / −S · blank = N/A Ground speed kn auto-sync with EW/NS True track ° from north · auto-sync with EW/NS

Vertical & geo−baro Vertical-rate source Vertical rate ft/min +up · blank = N/A GNSS − baro ft blank = N/A

Aircraft Status (TC 28)

BDS 6,1 — DO-260B: subtype 1 Emergency/Priority + Mode A; subtype 2 TCAS/ACAS RA Broadcast. Subtypes 0 / 3–7 reserved.

Subtype Subtype

Identity ICAO address 6 hex Capability (CA)

Emergency / Priority & Mode A Emergency/Priority Status Mode A code 4 octal · 7500/7600/7700 force status

DO-260B: 7500→unlawful interference (5), 7600→no comms (4), 7700→general emergency (1). Code 3000 disables Mode A broadcast in the field.

Target State and Status (TC 29)

BDS 6,2 — DO-260B subtype 1 only (selected altitude/heading, baro setting, NACp/SIL, MCP/FCU modes, TCAS operational). Subtype 0 is DO-260A and is not used here.

Subtype Subtype

Identity ICAO address 6 hex Capability (CA)

Selected altitude & baro Selected altitude type Selected altitude ft blank = N/A · 32 ft LSB Barometric pressure setting mb blank = N/A · 800–1209.5

Selected heading Heading available Selected heading ° 0–360 · LSB ≈ 0.703°

Integrity & accuracy NAC_p SIL SIL supplement (per sample) NIC_baro cross-checked

MCP / FCU modes & TCAS MCP/FCU mode bits valid Autopilot engaged VNAV mode engaged Altitude hold mode Approach mode TCAS / ACAS operational

Hex

Aircraft Identification (TC 1–4)

Position (TC 0 / 5–18)

GNSS Position (TC 20–22)

Airborne Velocity (TC 19)

Aircraft Status (TC 28)

Target State and Status (TC 29)

Aircraft Operational Status (TC 31)

Pick position