Meteorological data - System-wide Information Management

System Overview

MET-SWIM (System of Wide Information Management) is the aeronautical meteorological data distribution platform operated by the Aeronautical Meteorological Section of the Czech Hydrometeorological Institute (CHMI). The system provides standardized access to aviation weather information in compliance with ICAO and WMO standards for System-Wide Information Management.

System Availability

24/7 Continuous Operation: The MET-SWIM platform operates continuously with uninterrupted availability, ensuring real-time access to critical aeronautical meteorological data at all times.

Data Products and Structure

MET-SWIM delivers aeronautical meteorological products for Czech airports including:

  • Praha - Ruzyně (LKPR) - Václav Havel Airport Prague
  • Brno - Tuřany (LKTB) - Brno-Tuřany Airport
  • Ostrava - Mošnov (LKMT) - Leoš Janáček Airport Ostrava
  • Karlovy Vary (LKKV) - Karlovy Vary International Airport
  • České Budějovice (LKCS)
  • Vodochody (LKVO)
  • Kunovice (LKKU)
  • Čáslav (LKCV)
  • Pardubice (LKPD)
  • Praha - Kbely (LKKB)
  • Náměšť nad Oslavou (LKNA)

Available Data Formats

IWXXM Format (Primary Format)

The system provides meteorological data primarily in **IWXXM (ICAO Meteorological Information Exchange Model)** format, which includes:
Technical Specifications:

  • Format Type: XML/GML-based (Geography Markup Language) standardized format
  • Schema Version: IWXXM 3.0 (or latest ICAO-approved version)
  • Encoding: UTF-8
  • Namespace: Compliant with WMO and ICAO namespace conventions
  • Validation: Schema-validated XML ensuring data integrity

Products Available

  • METAR (Meteorological Aerodrome Report)
    • Update Frequency: Every 30 minutes (at :00 and :30 past each hour)
    • SPECI: Special reports issued when significant weather changes occur between routine observations
  • METREPORTR (Meteorological Aerodrome Report)
    • Update Frequency: Every 1 minute
  • TAF (Terminal Aerodrome Forecast)
    • Issued every 6 hours with 9, 18, or 30-hour validity periods
  • SIGMET (Significant Meteorological Information)
    • Issued as needed for hazardous weather phenomena
  • AIRMET (Airmen's Meteorological Information)
    • For phenomena affecting low-level flights
  • Other Products: Weather warnings, special observations, trend forecasts

Technical Features

  • Compliance: Fully compliant with ICAO Annex 3 (Amendment 79) and WMO No. 306 standards
  • Access Protocol: HTTP/HTTPS RESTful access
  • Access: Publicly available through the web interface without authentication
  • Machine-Readable: Designed for automated processing and integration into aviation systems
  • Geospatial Data: GML encoding for precise geographical features (runways, observation points, meteorological phenomena)
  • Metadata: Rich metadata structure including observation time, validity periods, issuing authority, and quality indicators

Data Structure

IWXXM Message Structure:

├── Header (Message metadata, issue time, issuing center)
├── Observation Data
│ ├── Location (coordinates, elevation, station identifier)
│ ├── Observation Time (UTC timestamp)
│ ├── Meteorological Parameters
│ │ ├── Temperature and Dew Point
│ │ ├── Pressure (QNH, QFE)
│ │ ├── Wind (direction, speed, gusts, variability)
│ │ ├── Visibility (prevailing and minimum)
│ │ ├── Weather Phenomena (present and recent)
│ │ ├── Cloud Layers (amount, height, type)
│ │ └── Runway State (if applicable)
│ └── Trend Forecast (when included)
└── Footer (Digital signature, validation status)

Traditional Alphanumeric Codes (TAC)

Legacy Format Availability:**

  • Format: Traditional ICAO alphanumeric text format (e.g., "METAR LKPR 181200Z...")
  • Encoding: ASCII/Plain text
  • Purpose: Backward compatibility with legacy systems
  • Update Frequency: Synchronized with IWXXM updates
  • Access: Available alongside IWXXM format

Data Update Schedules and Triggers

METAR Observations

  • Routine Updates: Every 30 minutes
    • :00 and :30 past each hour (UTC)
    • Example: 12:00, 12:30, 13:00, 13:30...
  • SPECI (Special Reports): Issued immediately when:
    • Wind direction changes ≥60° with mean speed ≥10 knots
    • Wind speed changes ≥10 knots
    • Visibility improves/deteriorates across specified thresholds (800m, 1500m, 3000m, 5000m)
    • Cloud base rises/lowers across specified heights (200ft, 500ft, 1000ft)
    • Weather phenomena commence, cease, or intensify (thunderstorms, precipitation, fog)
    • Temperature changes significantly
    • Pressure changes rapidly (tendencies)

METREPORT Observations

  • Routine Updates: Every 1 minute

TAF Forecasts

  • Standard Issue Times: 00:00, 03:00 (only for LKPR), 06:00, 09:00 (only for LKPR), 12:00, 15:00 (only for LKPR), 18:00 UTC, 21:00 (only for LKPR),
  • Amendments: Issued when forecast conditions significantly differ from actual observations
  • Corrections: Issued when errors are detected in previously issued TAF

SIGMET/AIRMET

  • Event-Driven: Issued as soon as hazardous phenomena are identified or forecast
  • Validity: Typically 4 hours maximum
  • Updates: As phenomena evolve or new information becomes available

Technical Implementation

SWIM Architecture Principles

  • Service-Oriented Architecture (SOA): Modular, loosely coupled services
  • Standardized Information Exchange: ICAO/WMO-compliant data schemas
  • Machine-to-Machine (M2M) Communication: Automated data exchange without human intervention
  • Geographic Markup Language (GML): For spatial meteorological features including:
    • Point observations (aerodrome locations)
    • Linear features (flight routes, wind shear zones)
    • Polygonal areas (SIGMET regions, weather fronts)
    • Three-dimensional volumes (cloud layers, icing areas)

Data Access Methods:

  • Web Interface: Human-readable display with latest observations
  • Direct File Access: Individual IWXXM/XML files per observation
  • RESTful API (for registered users): Programmatic access with query parameters
  • Web Services: SOAP/REST endpoints for system integration

Quality Assurance:

  • Automated Validation: Schema validation for all IWXXM messages
  • Quality Control Flags: Included in data structure
  • Observation Metadata: Including quality indicators, automated vs. manual observations
  • Traceability: Full audit trail of data generation and dissemination

Data Retention:

  • Real-time Access: Latest observations and forecasts
  • Historical Archive: Previous observations available (access varies by user type)
  • Data Persistence: Guaranteed availability according to ICAO standards

System Reliability and Performance

  • Uptime: 99.9%+ availability target
  • Redundancy: Backup systems and failover mechanisms
  • Update Latency: <2 minute from observation to publication
  • Data Integrity: Checksums and digital signatures for verification
  • Security: HTTPS encryption for all data transmission

Technical Standards and Compliance

  • ICAO Annex 3: Meteorological Service for International Air Navigation (Amendment 79+)
  • WMO No. 306: Manual on Codes (International Codes)
  • IWXXM Version: 3.0 or latest approved version
  • XML Schema: W3C XML Schema Definition (XSD)
  • GML: OGC Geography Markup Language 3.2.1
  • Character Encoding: UTF-8 throughout
  • Time Standard: UTC (Coordinated Universal Time) for all timestamps
  • Coordinate Reference System: WGS-84 for geospatial data

User Access and Registration

Public Access (Unrestricted)

  • IWXXM format data: Freely accessible 24/7 without registration
  • Traditional TAC format: Available without authentication
  • Web Interface: Direct browser access to latest meteorological reports
  • API Access: Direct HTTP/HTTPS requests to data endpoints
  • No Rate Limiting: For standard meteorological products