vACDM Integration

A-CDM departure milestone integration with vACDM

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vACDM VATSWIM Integration Guide

> Integration guide for connecting vACDM (virtual Airport Collaborative Decision Making) instances with VATSWIM.

Overview

vACDM instances push A-CDM departure milestone data to VATSWIM, enabling centralized departure readiness tracking across the VATSIM network. VATSWIM also polls registered vACDM providers for real-time updates.

Architecture

vACDM Instance ──push──> POST /api/swim/v1/ingest/cdm.php ──> swim_flights + sp_CDM_UpdateReadiness ↕ VATSWIM daemon <──poll── vACDM Provider API tmi_flow_providers

Endpoint

Method	Path	Auth	Batch
POST	`/api/swim/v1/ingest/cdm.php`	`swim_sys_` or `swim_par_` with `cdm` authority	500

A-CDM Milestones

VATSWIM supports the standard A-CDM milestone framework:

Milestone	Field	Type	Description
TOBT	`tobt`	ISO 8601 datetime	Target Off-Block Time
TSAT	`tsat`	ISO 8601 datetime	Target Startup Approval Time
TTOT	`ttot`	ISO 8601 datetime	Target Takeoff Time
ASAT	`asat`	ISO 8601 datetime	Actual Startup Approval Time
EXOT	`exot`	Integer (minutes)	Expected Taxi Out Time

SWIM Database Mapping

CDM Field	SWIM Column
`tobt`	`target_off_block_time`
`tsat`	`target_startup_approval_time`
`ttot`	`target_takeoff_time`
`asat`	`actual_startup_approval_time`
`exot`	`expected_taxi_out_time`

Readiness States

The readiness_state field tracks the departure readiness lifecycle:

State	Description	Transition
`PLANNING`	Flight plan filed, pilot not yet at gate	Initial state
`BOARDING`	At gate, passengers boarding	After gate assignment
`READY`	Ready for pushback, all checks complete	After boarding complete
`TAXIING`	Pushed back, taxiing to runway	After pushback approved
`CANCELLED`	Flight cancelled	Terminal state

VATSWIM calls sp_CDM_UpdateReadiness in VATSIM_TMI to update the readiness state, which feeds the GDT (Ground Delay Table) and compliance tracking.

Payload Format

{ "updates": [ { "callsign": "BAW123", "gufi": "VAT-20260306-BAW123-EGLL-KJFK", "airport": "EGLL", "tobt": "2026-03-06T14:30:00Z", "tsat": "2026-03-06T14:35:00Z", "ttot": "2026-03-06T14:40:00Z", "asat": "2026-03-06T14:36:00Z", "exot": 5, "readiness_state": "READY", "source": "VACDM" } ] }

Field Requirements

Field	Required	Notes
`callsign`	Yes	Aircraft callsign for flight lookup
`gufi`	No	Direct GUFI lookup (faster if known)
`airport`	No	Departure airport ICAO (helps with disambiguation)
`tobt`	No	At least one milestone must be present
`tsat`	No
`ttot`	No
`asat`	No
`exot`	No	Minutes (integer)
`readiness_state`	No	Must be a valid state (see above)
`source`	No	Defaults to your API key's source_id

Example Request

curl -X POST "https://perti.vatcscc.org/api/swim/v1/ingest/cdm.php" \ -H "Authorization: Bearer swim_sys_your_key_here" \ -H "Content-Type: application/json" \ -d '{ "updates": [ { "callsign": "BAW123", "airport": "EGLL", "tobt": "2026-03-06T14:30:00Z", "tsat": "2026-03-06T14:35:00Z", "readiness_state": "READY" } ] }'

Response

{
  "success": true,
  "processed": 1,
  "updated": 1,
  "not_found": 0,
  "readiness_updated": 1,
  "errors": []
}

Multi-Airport Support

vACDM instances can serve multiple airports. Each update includes the airport field to identify which airport's CDM process the milestone belongs to.

When polling, VATSWIM discovers vACDM providers via the tmi_flow_providers table, which stores:

Provider API URL
Supported airports
Sync interval and status
Authentication credentials

Provider Registration

To register your vACDM instance as a VATSWIM CDM provider:

1. Contact the vATCSCC development team

2. Provide your vACDM API endpoint URL

3. List the airports your instance serves

4. You'll receive a provider_id in the tmi_flow_providers table

Once registered, VATSWIM's vacdm_poll_daemon.php will poll your API every 120 seconds for updates.

Rate Limits and Batching

Maximum batch size: 500 CDM updates per request
Rate limit: 30,000/min (system), 3,000/min (partner)
Recommended cadence: Push updates when milestones change, not on a fixed timer
Deduplication: VATSWIM skips updates where all fields match current values

Circuit Breaker

The poll daemon uses a per-provider circuit breaker:

Window: 60 seconds
Max errors: 6 errors within the window
Cooldown: 180 seconds (3 minutes)

If your provider API returns repeated errors, polling will pause for 3 minutes before retrying.

Client SDK

A JavaScript/Node.js client library is available at integrations/connectors/vacdm/.

const { VATSWIMConnector } = require('./vatswim-connector');
const connector = new VATSWIMConnector('swim_sys_your_key_here');

await connector.sendCDMUpdates([{
    callsign: 'BAW123',
    airport: 'EGLL',
    tobt: '2026-03-06T14:30:00Z',
    readiness_state: 'READY'
}]);