📡 ACARS Message Handling

Real-time aircraft datalink message ingestion, decoding, and analysis

🚀 Quick Start

Get ACARS messages flowing in under 5 minutes:

📋
Prerequisites

Docker and Docker Compose installed

SDR hardware (RTL-SDR or similar)

SkySpy Django backend running

# 1. Add ACARS services to your docker-compose.yml
# 2. Start the stack
docker-compose up -d

# 3. Start the ACARS listener
python manage.py run_acars

# 4. Verify messages are flowing
curl http://localhost:8000/api/v1/acars/status/

✅
Success!
You should see "running": true in the response. Messages will appear in the web UI within seconds.

📖 Overview

SkySpy receives, decodes, stores, and displays real-time ACARS (Aircraft Communications Addressing and Reporting System) and VDL2 (VHF Data Link Mode 2) messages from aircraft. The system integrates with popular SDR-based decoders via the acars_router container.

✨ Key Features

🔌
Dual Protocol Support
ACARS (VHF) and VDL Mode 2 on separate UDP ports

⚡
Real-time Streaming
Socket.IO-based live message delivery to connected clients

🏷️
Message Enrichment
Automatic airline identification and label decoding

🔬
libacars Integration
Advanced decoding of FANS-1/A, CPDLC, and MIAM messages

🔄
Deduplication
LRU cache-based duplicate message filtering (30s TTL)

📊
Statistics & Analytics
Comprehensive message analytics and trending

🏗️ Architecture

System Data Flow

flowchart TB
    subgraph Hardware["📻 SDR Hardware"]
        SDR[RTL-SDR / AirSpy]
    end

    subgraph Decoders["🔧 Decoders"]
        ACARS[acarsdec<br/>VHF ACARS]
        VDL2[vdlm2dec<br/>VDL Mode 2]
        DUMP[dumpvdl2<br/>VDL Mode 2]
    end

    subgraph Router["🔀 Message Router"]
        AR[acars_router<br/>UDP Forwarder]
    end

    subgraph SkySpy["✈️ SkySpy Backend"]
        UDP5550["UDP :5550<br/>ACARS"]
        UDP5555["UDP :5555<br/>VDL2"]
        SVC[AcarsService<br/>Django]
    end

    subgraph Storage["💾 Storage & Delivery"]
        DB[(PostgreSQL)]
        WS[Socket.IO<br/>Broadcast]
        API[REST API]
    end

    SDR --> ACARS
    SDR --> VDL2
    SDR --> DUMP

    ACARS --> AR
    VDL2 --> AR
    DUMP --> AR

    AR --> UDP5550
    AR --> UDP5555

    UDP5550 --> SVC
    UDP5555 --> SVC

    SVC --> DB
    SVC --> WS
    SVC --> API

Message Processing Pipeline

sequenceDiagram
    participant D as Decoder
    participant R as acars_router
    participant U as UDP Listener
    participant S as AcarsService
    participant C as Cache
    participant DB as PostgreSQL
    participant WS as Socket.IO

    D->>R: JSON Message
    R->>U: Forward UDP
    U->>S: Parse JSON
    S->>S: Normalize Format
    S->>C: Check Duplicate
    alt New Message
        C-->>S: Not Found
        S->>S: Enrich (airline, label)
        S->>DB: Store Message
        S->>WS: Broadcast
    else Duplicate
        C-->>S: Found (skip)
    end

📨 Message Types

🏷️ Label Categories

ACARS messages are identified by two-character label codes. SkySpy categorizes these into logical groups:

🛫
OOOI Events Out/Off/On/In
Flight phase tracking from gate departure to arrival

Label	Name	Description	Emoji
`10`	Out	Aircraft departed gate	🚪
`11`	Off	Aircraft took off	🛫
`12`	On	Aircraft landed	🛬
`13`	In	Aircraft arrived at gate	🅿️
`80`	OOOI	Generic OOOI event	✈️

📍
Position Reports
Real-time aircraft location and navigation data

Label	Name	Description	Emoji
`H1`	Datalink	HF datalink / FANS-1/A message	📡
`H2`	Datalink	HF datalink message	📡
`2P`	Progress	Flight progress report	📈
`22`	Report	Periodic position report	🗺️
`C1`	Position	Position report	📌

🌤️
Weather
Meteorological requests and data

Label	Name	Description	Emoji
`QA` - `QF`	Weather	Weather requests and data	🌡️
`Q0` - `Q2`	Weather	Weather link messages	📊
`44`	Weather	Weather request/data	☁️
`21`	Advisory	Weather advisory	⚠️
`30` - `39`	Weather	METAR, TAF, PIREP, SIGMET	🌪️

⚙️
Operational
Flight operations and clearances

Label	Name	Description	Emoji
`15`	ETA	Estimated Time of Arrival	⏱️
`16`	Departure	Departure message	🛫
`17`	Arrival	Arrival message	🛬
`20`	Request	Operational request	📋
`33`	ATIS	Automatic Terminal Info	📢
`B1` - `B9`	Clearance	Departure/oceanic clearances	✅

🔧
System/Technical
Aircraft systems monitoring

Label	Name	Description	Emoji
`SA`	System	System/general message	💻
`SQ`	Squitter	Ground station ID	📶
`5Z`	ACMS	Aircraft condition monitoring	🔍
`83`	Fuel	Fuel request/data	⛽
`50` - `59`	Maintenance	Engine, APU, system reports	🛠️

🎯
CPDLC/FANS
Controller-pilot data communications

Label	Name	Description	Emoji
`CA`	CPDLC	Controller-Pilot Data Link	🎙️
`CR`	CPDLC	CPDLC Request	📞
`A0` - `A7`	FANS	FANS-1/A application messages	🌐
`AD` - `AF`	ADS-C	Automatic Dependent Surveillance	📍

💬
Free Text
General text communications

Label	Name	Description	Emoji
`AA`	Free Text	General free text message	📝
`AB`	Free Text	Free text reply	↩️
`FA` - `FF`	Free Text	Various free text formats	💬
`_d`	Demand	Demand mode message	❗

🔌 Data Ingestion

UDP Listener Configuration

# Default ports
ACARS_UDP_PORT = 5550  # Standard ACARS messages
VDLM2_UDP_PORT = 5555  # VDL Mode 2 messages

Processing Steps

flowchart LR
    A["1️⃣ Reception"] --> B["2️⃣ Parsing"]
    B --> C["3️⃣ Normalization"]
    C --> D["4️⃣ Deduplication"]
    D --> E["5️⃣ Enrichment"]
    E --> F["6️⃣ Storage"]
    F --> G["7️⃣ Broadcast"]

Step	Description
1️⃣	UDP datagram received on port 5550 (ACARS) or 5555 (VDL2)
2️⃣	JSON payload decoded from UTF-8
3️⃣	Message format normalized to common schema
4️⃣	LRU cache check (30-second TTL)
5️⃣	Airline info extracted, label decoded, libacars parsing
6️⃣	Persisted to PostgreSQL database
7️⃣	Sent to Socket.IO subscribers

🚀 Starting the Service

# Using management command
python manage.py run_acars

# With custom ports
python manage.py run_acars --acars-port 5550 --vdlm2-port 5555

# Disable one listener
python manage.py run_acars --no-vdlm2

# Verbose logging
python manage.py run_acars -v 2

📋 Message Formats

Decoder Comparison

Feature	acarsdec	vdlm2dec	dumpvdl2
Protocol	ACARS VHF	VDL2	VDL2
Frequencies	129-137 MHz	136 MHz band	136 MHz band
Output Format	Flat JSON	Nested JSON	Nested JSON
ICAO Field	`icao`	`avlc.src.addr`	`avlc.src.addr`
Timestamp	Unix float	sec/usec object	sec/usec object
Signal Level	`level` (dB)	`sig_level` (dB)	`sig_level` (dB)

📥 Input: acarsdec Format

{
  "timestamp": 1703001234.567,
  "freq": 131.55,
  "channel": 0,
  "icao": "ABC123",
  "tail": "N12345",
  "flight": "UAL456",
  "label": "SA",
  "text": "POSITION REPORT...",
  "level": -32,
  "error": 0
}

📥 Input: dumpvdl2 Format

{
  "vdl2": {
    "t": { "sec": 1703001234, "usec": 567000 },
    "freq": 136975000,
    "sig_level": -28,
    "avlc": {
      "src": { "addr": "ABC123" },
      "acars": {
        "reg": ".N12345",
        "flight": "AAL123",
        "label": "SA",
        "msg_text": "POSITION REPORT..."
      }
    }
  }
}

📤 Output: Normalized Schema

Field	Type	Description
`timestamp`	float	Unix timestamp
`source`	string	`acars` or `vdlm2`
`channel`	string	Receiver channel
`frequency`	float	Frequency in MHz
`icao_hex`	string	Aircraft ICAO hex address
`registration`	string	Aircraft registration (tail)
`callsign`	string	Flight callsign
`label`	string	ACARS message label
`block_id`	string	Message block identifier
`msg_num`	string	Message sequence number
`ack`	string	Acknowledgment flag
`mode`	string	ACARS mode
`text`	string	Message text content
`signal_level`	float	Signal strength (dB)
`error_count`	int	Decoding errors
`station_id`	string	Receiving station ID

💾 Database Model

class AcarsMessage(models.Model):
    SOURCE_CHOICES = [
        ('acars', 'ACARS'),
        ('vdlm2', 'VDL Mode 2'),
    ]

    timestamp = models.DateTimeField(db_index=True)
    source = models.CharField(max_length=10, choices=SOURCE_CHOICES)
    channel = models.CharField(max_length=10, blank=True, null=True)
    frequency = models.FloatField(blank=True, null=True)
    icao_hex = models.CharField(max_length=10, db_index=True)
    registration = models.CharField(max_length=20, db_index=True)
    callsign = models.CharField(max_length=10, db_index=True)
    label = models.CharField(max_length=10, db_index=True)
    block_id = models.CharField(max_length=5)
    msg_num = models.CharField(max_length=10)
    ack = models.CharField(max_length=5)
    mode = models.CharField(max_length=5)
    text = models.TextField()
    decoded = models.JSONField(blank=True, null=True)
    signal_level = models.FloatField()
    error_count = models.IntegerField()
    station_id = models.CharField(max_length=50)

    class Meta:
        db_table = 'acars_messages'
        indexes = [
            models.Index(fields=['icao_hex', 'timestamp']),
            models.Index(fields=['label', 'timestamp']),
        ]
        ordering = ['-timestamp']

🏷️ Message Enrichment

Each message is automatically enriched with additional metadata:

✈️

Airline Information

{
    "airline": {
        "icao": "UAL",
        "iata": "UA",
        "name": "United Airlines",
        "flight_number": "456"
    }
}

🏷️

Label Information

{
    "label_info": {
        "name": "Position Report",
        "description": "Aircraft position and progress reports"
    }
}

🔍

Decoded Text (when applicable)

{
    "decoded_text": {
        "message_type": "Position Report",
        "position": {"lat": 45.1234, "lon": -122.5678},
        "altitude_ft": 35000,
        "airports_mentioned": ["KSEA", "KJFK"]
    }
}

🔄 Deduplication

Messages are deduplicated using an LRU cache with a 30-second TTL:

# Hash computation uses:
# - Timestamp (rounded to second)
# - ICAO hex address
# - Message label
# - First 50 characters of text

cache = LRUCache(maxsize=10000, ttl_seconds=30)

🌐 API Reference

Base URL

/api/v1/acars/

📋 List Messages

GET /api/v1/acars/

Query Parameters:

Parameter	Type	Default	Description
`hours`	int	24	Time range filter
`source`	string	-	Filter by source (`acars`/`vdlm2`)
`icao_hex`	string	-	Filter by aircraft ICAO
`callsign`	string	-	Filter by callsign
`label`	string	-	Filter by message label
`limit`	int	-	Maximum results

Response:

{
  "messages": [
    {
      "id": 12345,
      "timestamp": "2024-01-15T10:30:00Z",
      "source": "acars",
      "frequency": 131.55,
      "icao_hex": "ABC123",
      "callsign": "UAL456",
      "label": "SA",
      "text": "ETA KJFK 1430Z",
      "airline": {
        "icao": "UAL",
        "name": "United Airlines"
      },
      "label_info": {
        "name": "System",
        "description": "System message"
      }
    }
  ],
  "count": 1,
  "filters": {"hours": 24}
}

📊 Get Statistics

GET /api/v1/acars/stats/

Response:

{
  "total_messages": 15420,
  "last_hour": 245,
  "last_24h": 5832,
  "by_source": {
    "acars": 3200,
    "vdlm2": 2632
  },
  "top_labels": [
    {"label": "SA", "count": 1245},
    {"label": "H1", "count": 892}
  ]
}

📈 Get Message Breakdown

GET /api/v1/acars/stats/breakdown/

Query Parameters:

Parameter	Type	Default	Description
`hours`	int	24	Time range
`use_cache`	bool	true	Use cached stats

Response:

{
  "total_messages": 5832,
  "time_range_hours": 24,
  "by_source": {"acars": 3200, "vdlm2": 2632},
  "by_label": [
    {
      "label": "SA",
      "count": 1245,
      "name": "System",
      "description": "System message",
      "category": "system"
    }
  ],
  "by_category": [
    {
      "category": "oooi",
      "name": "OOOI Events",
      "count": 890,
      "percentage": 15.3
    }
  ],
  "top_frequencies": [
    {"frequency": 131.55, "frequency_mhz": "131.550", "count": 2100}
  ]
}

🏢 Get Airline Statistics

GET /api/v1/acars/stats/airlines/

Response:

{
  "airlines": [
    {
      "airline_icao": "UAL",
      "airline_iata": "UA",
      "airline_name": "United Airlines",
      "message_count": 456,
      "unique_flights": 12
    }
  ],
  "total_with_airline_info": 4500,
  "total_messages": 5832
}

📉 Get Message Trends

GET /api/v1/acars/stats/trends/

Query Parameters:

Parameter	Type	Default	Description
`hours`	int	24	Time range
`interval`	string	hour	Interval type (`hour`/`day`)

Response:

{
  "intervals": [
    {
      "timestamp": "2024-01-15T10:00:00Z",
      "total": 245,
      "acars": 145,
      "vdl2": 100,
      "unique_aircraft": 45,
      "unique_flights": 38
    }
  ],
  "peak_interval": {
    "timestamp": "2024-01-15T14:00:00Z",
    "count": 312
  },
  "hourly_distribution": [
    {"hour": 0, "count": 89},
    {"hour": 1, "count": 67}
  ]
}

🔴 Get Receiver Status

GET /api/v1/acars/status/

Response:

{
  "running": true,
  "acars": {
    "total": 15420,
    "last_hour": 245,
    "errors": 12,
    "duplicates": 89
  },
  "vdlm2": {
    "total": 12350,
    "last_hour": 198,
    "errors": 5,
    "duplicates": 45
  },
  "buffer_size": 100
}

🏷️ Get Label Reference

GET /api/v1/acars/labels/

Response:

{
  "labels": {
    "H1": {"name": "Datalink", "description": "HF datalink message"},
    "SA": {"name": "System", "description": "System message"}
  },
  "sources": {
    "acars": "ACARS (VHF)",
    "vdlm2": "VDL Mode 2"
  }
}

🖥️ Frontend Integration

Socket.IO Connection

sequenceDiagram
    participant Client as 🖥️ Browser
    participant WS as 🔌 Socket.IO
    participant Django as 🐍 Django

    Client->>WS: Connect io('/acars')
    WS->>Django: Establish connection
    Django-->>Client: Connection ACK

    Client->>WS: socket.emit('subscribe', {topic: 'messages'})

    loop Real-time Updates
        Django->>WS: New ACARS message
        WS->>Client: acars:message event
    end

Socket.IO Connection:

import { io } from 'socket.io-client';

const socket = io('https://hostname/acars', {
  path: '/socket.io/',
  transports: ['websocket', 'polling']
});

Subscribe to Messages:

socket.emit('subscribe', { topic: 'messages' });

📡 Events

Event	Description
`acars:message`	New ACARS message received
`acars:snapshot`	Initial message batch on connect

Listening for Events:

socket.on('acars:message', (data) => {
  console.log('New ACARS message:', data);
});

socket.on('acars:snapshot', (data) => {
  console.log('Initial messages:', data);
});

useAircraftAcars Hook

import { useAircraftAcars } from './hooks/useAircraftAcars';

const {
  acarsMessages,        // Array of messages
  acarsHours,           // Time range filter
  setAcarsHours,        // Update time range
  acarsCompactMode,     // Display mode
  setAcarsCompactMode,  // Toggle compact mode
  acarsQuickFilters,    // Active category filters
  setAcarsQuickFilters, // Update filters
  acarsLoaded,          // Loading state
} = useAircraftAcars({
  hex: 'ABC123',
  baseUrl: 'http://localhost:8000',
  callsign: 'UAL456',
  activeTab: 'acars',
  wsRequest,
  wsConnected,
});

🏷️ Message Categories (Frontend)

const quickFilterCategories = {
  position: {
    name: 'Position',
    labels: ['C1', 'SQ', '47', '2Z', 'AD', 'AE']
  },
  weather: {
    name: 'Weather',
    labels: ['15', '30', '31', '32', '33', '34', '35', '36', '37', '38', '39', '44', '80', '81', '83', '3M', '3S']
  },
  oooi: {
    name: 'OOOI',
    labels: ['10', '11', '12', '13', '14', '16', '17']
  },
  operational: {
    name: 'Operational',
    labels: ['H1', 'H2', '5Z', '20', '21', '22', '23', '24', '25', '26', '27', '28', '29', 'B1', 'B2', 'B9']
  },
  freetext: {
    name: 'Free Text',
    labels: ['AA', 'AB', 'FA', 'FF', 'F3', 'F5', 'F7']
  },
  maintenance: {
    name: 'Maintenance',
    labels: ['50', '51', '52', '53', '54', '55', '56', '57', '58', '59', '5A', '5U']
  },
};

AcarsTab Component Features

⏱️
Time Range Selector
Filter messages by time (1h to 7 days)

🔀
View Toggle
Compact or expanded message display

🏷️
Quick Filters
Category-based filtering chips

📜
Message List
Scrollable list with expand/collapse

🔍
Decoded Data
Displays enriched message information

🔧 External Decoder Integration

Integration Architecture

flowchart LR
    subgraph Decoders["🔧 SDR Decoders"]
        A[acarsdec]
        V[vdlm2dec]
        D[dumpvdl2]
    end

    subgraph Router["🔀 acars_router"]
        R[UDP Aggregator]
    end

    subgraph SkySpy["✈️ SkySpy"]
        S5550[":5550 ACARS"]
        S5555[":5555 VDL2"]
    end

    A -->|UDP| R
    V -->|UDP| R
    D -->|UDP| R
    R -->|UDP| S5550
    R -->|UDP| S5555

acars_router Configuration

# docker-compose.yml
services:
  acars_router:
    image: ghcr.io/sdr-enthusiasts/acars_router:latest
    environment:
      # Input ports (receive from decoders)
      - AR_LISTEN_UDP_ACARS=5550
      - AR_LISTEN_UDP_VDLM2=5555
      # Output to SkySpy
      - AR_SEND_UDP_ACARS=skyspy:5550
      - AR_SEND_UDP_VDLM2=skyspy:5555
    ports:
      - "5550:5550/udp"
      - "5555:5555/udp"

acarsdec Configuration

acarsdec:
  image: ghcr.io/sdr-enthusiasts/docker-acarsdec:latest
  environment:
    - FEED_ID=MY-STATION
    - FREQUENCIES=130.025;130.425;130.450;131.125;131.550
    - OUTPUT_SERVER=acars_router:5550

dumpvdl2 / vdlm2dec Configuration

vdlm2dec:
  image: ghcr.io/sdr-enthusiasts/docker-vdlm2dec:latest
  environment:
    - FEED_ID=MY-STATION
    - FREQUENCIES=136.650;136.700;136.800;136.975
    - OUTPUT_SERVER=acars_router:5555

💡
Direct Integration
Skip acars_router for simpler setups:
acarsdec:
  environment:
    - OUTPUT_SERVER=skyspy:5550

vdlm2dec:
  environment:
    - OUTPUT_SERVER=skyspy:5555

🔬 libacars Integration

SkySpy integrates with libacars for advanced message decoding.

Supported Formats

🌐
FANS-1/A ADS-C
Automatic Dependent Surveillance - Contract

🎙️
FANS-1/A CPDLC
Controller-Pilot Data Link Communications

📦
MIAM
Media Independent Aircraft Messaging

✈️
Airline-Specific
Various proprietary message formats

Decodable Labels

decodable_labels = {
    "H1", "H2",           # FANS-1/A
    "SA", "S1", "S2",     # System address
    "AA", "AB", "AC",     # ARINC 622
    "BA", "B1"-"B6",      # Various airline formats
    "_d", "2Z", "5Z",     # MIAM compressed
}

Usage

from skyspy.services.libacars_binding import (
    decode_acars_apps,
    is_available,
    MsgDir,
)

if is_available():
    result = decode_acars_apps(
        label="H1",
        text="...",
        direction=MsgDir.AIR_TO_GROUND,
        use_cache=True
    )

Performance Features

Feature	Description
🗄️ LRU Cache	Decoded results cached to avoid redundant processing
⚡ Circuit Breaker	Automatic error recovery and rate limiting
📊 Prometheus Metrics	Export decoding statistics

⚙️ Configuration

Django Settings

# skyspy_django/skyspy/settings.py

# UDP listener ports
ACARS_UDP_PORT = int(os.environ.get('ACARS_UDP_PORT', 5550))
VDLM2_UDP_PORT = int(os.environ.get('VDLM2_UDP_PORT', 5555))

# Message retention (for cleanup tasks)
ACARS_RETENTION_DAYS = int(os.environ.get('ACARS_RETENTION_DAYS', 30))

# Cache settings
ACARS_STATS_CACHE_TIMEOUT = 120  # seconds

Environment Variables

Variable	Default	Description
`ACARS_UDP_PORT`	5550	UDP port for ACARS messages
`VDLM2_UDP_PORT`	5555	UDP port for VDL2 messages
`ACARS_RETENTION_DAYS`	30	Days to retain messages
`LIBACARS_DISABLED`	false	Disable libacars decoding

Docker Compose

services:
  skyspy:
    environment:
      - ACARS_UDP_PORT=5550
      - VDLM2_UDP_PORT=5555
      - ACARS_RETENTION_DAYS=30
    ports:
      - "5550:5550/udp"
      - "5555:5555/udp"

🧪 Testing

Mock ACARS Service

A mock ACARS service is available for development and testing:

cd test/acars-mock
docker build -t acarshub-mock .
docker run -d \
  --name acarshub-mock \
  -p 8080:8080 \
  -p 5550:5550/udp \
  -p 5555:5555/udp \
  -e MOCK_ENABLED=true \
  -e RELAY_HOST=skyspy \
  -e RELAY_PORT=5550 \
  acarshub-mock

Mock Features

Feature	Description
📨 Realistic Messages	Creates authentic ACARS/VDL2 messages
📍 Position Reports	Uses real aircraft positions when available
🔀 Multiple Formats	Generates both acarsdec and dumpvdl2 formats
🖥️ Web Interface	Monitor at http://localhost:8080
⚡ Socket.IO Streaming	Real-time message feed
💉 Message Injection	POST custom messages via API

Mock API Endpoints

Endpoint	Method	Description
`/api/stats`	`GET`	Service statistics
`/api/messages`	`GET`	Recent messages
`/api/mock/start`	`POST`	Start mock generation
`/api/mock/stop`	`POST`	Stop mock generation
`/api/inject`	`POST`	Inject custom message

Unit Tests

# Run ACARS service tests
python manage.py test skyspy.tests.test_services_acars

# Run with coverage
pytest skyspy/tests/test_services_acars.py --cov=skyspy.services.acars

Test Coverage

LRU cache operations and TTL expiration
Message hash computation and deduplication
Format normalization (ACARS and VDL2)
Frequency conversion (Hz to MHz)
Statistics tracking
Message storage and broadcasting
Service lifecycle (start/stop)

🚨 Troubleshooting

No Messages Received

⚠️
Problem
The ACARS listener is running but no messages appear

Checklist:

Check UDP ports: Ensure ports 5550/5555 are accessible
Verify decoder output: Check acarsdec/vdlm2dec logs
Check acars_router: Verify forwarding configuration
Firewall: Ensure UDP traffic is allowed

# Test UDP connectivity
nc -u localhost 5550 <<< '{"test": true}'

High Duplicate Count

ℹ️
Information
Duplicates are normal when multiple receivers pick up the same message

The 30-second TTL window filters most duplicates
Check if multiple decoders are forwarding the same messages
Consider adjusting LRU_CACHE_SIZE for high-traffic environments

libacars Not Working

❓
Diagnostic
Check if libacars is available and functioning

from skyspy.services.libacars_binding import is_available, get_backend

print(f"Available: {is_available()}")
print(f"Backend: {get_backend()}")

Database Growth

⚠️
Problem
Database size growing rapidly

Solution:

# Check message count
from skyspy.models import AcarsMessage
print(AcarsMessage.objects.count())

# Manual cleanup (older than 30 days)
from datetime import timedelta
from django.utils import timezone
cutoff = timezone.now() - timedelta(days=30)
AcarsMessage.objects.filter(timestamp__lt=cutoff).delete()

💡
Tip
Set ACARS_RETENTION_DAYS environment variable to automate cleanup

📚 Glossary

Term	Definition
ACARS	Aircraft Communications Addressing and Reporting System
VDL2	VHF Data Link Mode 2
OOOI	Out/Off/On/In - Flight phase events
CPDLC	Controller-Pilot Data Link Communications
ADS-C	Automatic Dependent Surveillance - Contract
FANS-1/A	Future Air Navigation System
MIAM	Media Independent Aircraft Messaging
libacars	C library for decoding ACARS message payloads

🔗 Related Resources

Resource	Description
SDR Enthusiasts ACARS Hub	Complete ACARS receiving solution
acars_router	Message aggregation and forwarding
libacars	C library for ACARS decoding
acarsdec	Multi-channel ACARS decoder
dumpvdl2	VDL Mode 2 decoder

📡 ACARS Message Handling

🚀 Quick Start

Prerequisites

Success!

📖 Overview

✨ Key Features

Dual Protocol Support

Real-time Streaming

Message Enrichment

libacars Integration

Deduplication

Statistics & Analytics

🏗️ Architecture

System Data Flow

Message Processing Pipeline

📨 Message Types

🏷️ Label Categories

OOOI Events Out/Off/On/In

Position Reports

Weather

Operational

System/Technical

CPDLC/FANS

Free Text

🔌 Data Ingestion

UDP Listener Configuration

Processing Steps

🚀 Starting the Service

📋 Message Formats

Decoder Comparison

📥 Input: acarsdec Format

📥 Input: dumpvdl2 Format

📤 Output: Normalized Schema

💾 Database Model

🏷️ Message Enrichment

Airline Information

Label Information

Decoded Text (when applicable)

🔄 Deduplication

🌐 API Reference

Base URL

📋 List Messages

📊 Get Statistics

📈 Get Message Breakdown

🏢 Get Airline Statistics

📉 Get Message Trends

🔴 Get Receiver Status

🏷️ Get Label Reference

🖥️ Frontend Integration

Socket.IO Connection

📡 Events

useAircraftAcars Hook

🏷️ Message Categories (Frontend)

AcarsTab Component Features

Time Range Selector

View Toggle

Quick Filters

Message List

Decoded Data

🔧 External Decoder Integration

Integration Architecture

acars_router Configuration

acarsdec Configuration

dumpvdl2 / vdlm2dec Configuration

Direct Integration

🔬 libacars Integration

Supported Formats

FANS-1/A ADS-C

FANS-1/A CPDLC

MIAM

Airline-Specific

Decodable Labels

Usage

Performance Features

⚙️ Configuration

Django Settings

Environment Variables

Docker Compose

🧪 Testing

Mock ACARS Service

OOOI Events `Out/Off/On/In`