# at.adsb.datalink.message

> Published by [adsb.at](https://lexicon.garden/identity/did:plc:32thk4eifx4ou6mxevswgjhg)

✓ This is the authoritative definition for this NSID.

## Description

A captured aircraft datalink message (ACARS, VDL2, or HFDL). These are low-volume, high-value records that represent individual communications between aircraft and ground stations.

## Links

- [View on Lexicon Garden](https://lexicon.garden/lexicon/did:plc:32thk4eifx4ou6mxevswgjhg/at.adsb.datalink.message)
- [Documentation](https://lexicon.garden/lexicon/did:plc:32thk4eifx4ou6mxevswgjhg/at.adsb.datalink.message/docs)
- [Examples](https://lexicon.garden/lexicon/did:plc:32thk4eifx4ou6mxevswgjhg/at.adsb.datalink.message/examples)

## Definitions

### `at.adsb.datalink.message`

**Type**: `record`

A captured aircraft datalink message.

**Key**: `tid`

| Property | Type | Required | Description |
|----------|------|----------|-------------|
| `label` | `string` | No | ACARS message label (two-character code indicating message type). |
| `icaoHex` | `string` | No | ICAO 24-bit aircraft address in hexadecimal, if identifiable. |
| `callsign` | `string` | No | Flight callsign as identified in the message. |
| `position` | `ref` → `at.adsb.flight.defs#position` | No | Aircraft position at the time of the message, if included. |
| `protocol` | `string` | Yes | Datalink protocol the message was received on. |
| `sublabel` | `string` | No | ACARS sublabel for further message classification. |
| `createdAt` | `string` (datetime) | Yes |  |
| `capturedAt` | `string` (datetime) | Yes | When the message was received by the station. |
| `messageText` | `string` | No | Decoded message content. |
| `receiverDid` | `string` (did) | No | DID of the receiver that captured this message. |
| `frequencyMhz` | `string` | No | Frequency the message was received on, in MHz (e.g. '131.550'). |
| `registration` | `string` | No | Aircraft registration, if identifiable from the message. |
| `groundStation` | `ref` → `#groundStationInfo` | No | Ground station involved in the communication, if identifiable. |

### `at.adsb.datalink.message#groundStationInfo`

**Type**: `object`

Identification of the ground station involved in the datalink communication.

| Property | Type | Required | Description |
|----------|------|----------|-------------|
| `id` | `string` | No | Ground station identifier (e.g. HFDL station ID, VDL2 ground station address). |
| `name` | `string` | No | Human-readable ground station name (e.g. 'Shannon', 'Reykjavik'). |
| `location` | `ref` → `community.lexicon.location.geo` | No | Geographic position of the ground station. |

## Raw Schema

```json
{
  "id": "at.adsb.datalink.message",
  "defs": {
    "main": {
      "key": "tid",
      "type": "record",
      "record": {
        "type": "object",
        "required": [
          "protocol",
          "capturedAt",
          "createdAt"
        ],
        "properties": {
          "label": {
            "type": "string",
            "maxLength": 2,
            "description": "ACARS message label (two-character code indicating message type)."
          },
          "icaoHex": {
            "type": "string",
            "maxLength": 6,
            "description": "ICAO 24-bit aircraft address in hexadecimal, if identifiable."
          },
          "callsign": {
            "type": "string",
            "maxLength": 8,
            "description": "Flight callsign as identified in the message."
          },
          "position": {
            "ref": "at.adsb.flight.defs#position",
            "type": "ref",
            "description": "Aircraft position at the time of the message, if included."
          },
          "protocol": {
            "type": "string",
            "maxLength": 256,
            "description": "Datalink protocol the message was received on.",
            "knownValues": [
              "at.adsb.datalink.message#acars",
              "at.adsb.datalink.message#vdl2",
              "at.adsb.datalink.message#hfdl"
            ]
          },
          "sublabel": {
            "type": "string",
            "maxLength": 4,
            "description": "ACARS sublabel for further message classification."
          },
          "createdAt": {
            "type": "string",
            "format": "datetime"
          },
          "capturedAt": {
            "type": "string",
            "format": "datetime",
            "description": "When the message was received by the station."
          },
          "messageText": {
            "type": "string",
            "maxLength": 20480,
            "description": "Decoded message content.",
            "maxGraphemes": 2048
          },
          "receiverDid": {
            "type": "string",
            "format": "did",
            "description": "DID of the receiver that captured this message."
          },
          "frequencyMhz": {
            "type": "string",
            "maxLength": 20,
            "description": "Frequency the message was received on, in MHz (e.g. '131.550')."
          },
          "registration": {
            "type": "string",
            "maxLength": 10,
            "description": "Aircraft registration, if identifiable from the message."
          },
          "groundStation": {
            "ref": "#groundStationInfo",
            "type": "ref",
            "description": "Ground station involved in the communication, if identifiable."
          }
        }
      },
      "description": "A captured aircraft datalink message."
    },
    "groundStationInfo": {
      "type": "object",
      "properties": {
        "id": {
          "type": "string",
          "maxLength": 32,
          "description": "Ground station identifier (e.g. HFDL station ID, VDL2 ground station address)."
        },
        "name": {
          "type": "string",
          "maxLength": 640,
          "description": "Human-readable ground station name (e.g. 'Shannon', 'Reykjavik').",
          "maxGraphemes": 64
        },
        "location": {
          "ref": "community.lexicon.location.geo",
          "type": "ref",
          "description": "Geographic position of the ground station."
        }
      },
      "description": "Identification of the ground station involved in the datalink communication."
    }
  },
  "$type": "com.atproto.lexicon.schema",
  "lexicon": 1,
  "description": "A captured aircraft datalink message (ACARS, VDL2, or HFDL). These are low-volume, high-value records that represent individual communications between aircraft and ground stations."
}
```