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ESRL Global Systems Division

Aviation Related Data

This Document briefly describes the following types of Aviation related data that is processed in the GSD Central Facility:

  1. Automated Data from Aircraft
    • ACARS
    • AMDAR
    • BUFR - MDCRS, Lufthansa, TAMDAR
  2. PIREPs
  3. Aviation Weather Advisories
    • Airmets
    • Sigmets - Convective, Non-convective
    • Center Weather Advisories
  4. METARs

Automated Data from Aircraft

ACARS - Aircraft Communications Addressing and Reporting System

ACARS are real-time automated position and weather reports from commercial aircraft. GSD receives ACARS data from Arinc. This data comes from 6 different passenger or freight carriers: Delta, Northwest, United, American, United Parcel Service and Federal Express.

There are several formats of data that we receive from each. As new formats are defined, older ones are no longer used. The information in each ACARS message depends on the format. There is no WMO or other standard for ACARS formats, therefore there is variety in what and how information is reported.

In addition to weather information, a format may contain information about the flight, e.g: origin, destination, phase of flight, (takeoff, ascent, descent, etc.), flight number, tail number, and fuel on board. In general, all information is decoded and put into the NetCDF file, even if it is not of meteorological interest. One ACARS message may contain several individual reports:

Each message contains:

  • time of observation
  • position (latitude, longitude, altitude)

All reports contain:

  • Static air temperature
  • Wind Direction/Speed
  • In addition other reports contain:
  • Total air temperature
  • Other meteorological observations:
  • Vertical Acceleration (United WX format)
  • Coded Mean and Peak Turbulence (United WX Format)
  • Icing (Delta Icing Format)
  • Water Vapor (UPS 620)
  • Relative Humidity (UPS 620)

The number of reports translated varies throughout the week, as these are dependent on air traffic.

Report totals for 2 days:

06/01/2004 109,813
Wednesday 06/02/2004 140,681

AMDAR - Aircraft Meteorological data relay

AMDAR is the code for an automatic meteorological report from an aircraft. AMDARs contain much the same information as an ACARS message. Unlike ACARS, there is a WMO definition for an AMDAR message. It is defined to have:

  • Aircraft Identification
  • Latitude/Longitude
  • Flight Level
  • Time of observation
  • Temperature
  • Wind Direction and Speed
  • Turbulence Coded as 0 through 3; None, Light, Moderate, Severe
  • Vertical Gust

Report totals for 2 days:

06/01/2004 14,318
Wednesday 06/02/2004 13,545

MDCRS - Meteorological Data Collection and Reporting System

ARINC's Meteorological Data Collection and Reporting System (MDCRS) collects and organizes real-time automated position and weather reports. They forward these to the NWS. These are BUFR encoded and GSD ftp's these from the NWS telecommunication gateway. These are actually a subset of the same data that GSD receives directly from Arinc in text format. So the same meteorological data is contained in them: time of observation, position, temperature, wind direction and wind speed.

Lufthansa airlines

Other BUFR encoded data is from Lufthansa Airlines. GSD ftp's these from NWS. This data also include: time of observation, position, temperature, wind direction and wind speed.

Report totals for 2 days BUFR data:

06/01/2004 91,873
Wednesday 06/02/2004 119,390

TAMDAR - Tropospheric Airborne Meteorological Data Reporting

In the summer of 2004, GSD began receiving BUFR encoded TAMDAR data from AirDat LLC. These reports provide needed data from below 20,000 feet. The observational data include temperature, winds aloft, humidity, turbulence and icing. In addition, the observational data has quality control information associated with it.

This is part of the Great Lake Fleet Experiment in conjunction with GSD, NASA, NWS and AirDat.

PIREPs - Pilot Reports

PIREPs are pilot initiated text reports. GSD receives PIREPs via NOAAPORT. PIREPs have a defined text format that is generally adhered to. A PIREP begins with the SA identifier or collection site. The phenomena reported can include:

  • Location - Reported in relation to an airport, VOR or Navaid
  • Time - Time (UTC) of phenomena
  • Flight Level - Reported in 100s of feet, may contain a top and bottom level, and a flight indicator, e.g. climb, descent.
  • Aircraft Type - Type of aircraft the pilot is flying using ICAO identifiers
  • Sky Cover - Standard sky cover abbreviations followed by cloud bases in hundreds of feet
  • Weather - Weather encountered
  • Flight Visibility - Reported to the nearest whole statute mile
  • Temperature - Air temperature reported in degrees Celsius
  • Wind - Direction reported in degrees, and speed in knots
  • Turbulence - Intensity and altitude
  • Icing - Intensity and altitude
  • Remarks - Any information that can extend or clarify the report

Report totals for 2 days:

06/01/2004 1,670
Wednesday 06/02/2004 1,703

Aviation Weather Advisories

There are two types of scheduled in-flight advisories: Significant Meteorological (SIGMET) Advisories and Airman's Meteorological (AIRMET) Advisories. Airmets inform of conditions less severe than Sigmets. Center Weather Advisories (CWA) are unscheduled.

Convective Sigmets are bulletins issued hourly describing conditions for the western, central and eastern regions for thunderstorms and related phenomena. Since it is assumed that severe or greater turbulence, severe icing and low level wind shear will accompany these conditions, information on these are not included. Information about the convective activity include:

  • Location of storm as a shape relevant to VORs
  • Closed polygon Line, including width
  • Point with diameter
  • Thunderstorm is severe and/or embedded
  • Direction and speed storm is moving, reported in degrees North in knots
  • Intensity trend
  • Height of storm
  • Information on tornadoes, wind gusts or hail
  • Outlook for thunderstorms beyond the 2 hour valid period

Report Totals for 2 days:

Tuesday 06/01/2004 146
Wednesday 06/02/2004 151

Non-Convective Sigmets are issued for severe turbulence, severe icing, phenomena causing surface and or in-flight visibility to be less than 3 miles and volcanic eruption. The information included for this is:

  • Center originating the report
  • States or areas affected
  • Location of the phenomena, described in relation to VORs
  • Intensity, frequency, and type of condition Bottom/Top height value

Report Totals for 2 days:

06/01/2004 0
Wednesday 06/02/2004 0

NOTE: There are minimal non-convective sigmets in summer months.

Airmets are issued for similar phenomena to non-convective sigmets, but describe conditions at intensities lower than those which trigger sigmets. An airmet will be issued for moderate icing, moderate turbulence, sustained surface winds greater than or equal to 30 knots, low ceiling or extensive mountain obscuration. The same information is included as is that for a non-convective sigmet.

Report Totals for 2 days:

06/01/2004 209
Wednesday 06/02/2004 212

Center Weather Advisories, CWAs are issued to expand or update AIRMETs, SIGMETs or area forecasts and have a loosely defined text format. CWAs are used for 5 different phenomena, and each advisory will describe only one. These types are: convective, turbulence, ceiling and visibility, icing and wind shear. FAA header information contains the ARTCC identifier of the issuer, phenomenon and issuance numbers, type (urgent or not), and beginning and ending valid time. The location information should describe the phenomenon using ARTCC relevant points of reference, e.g. VORs. This location is either a point, line or polygon. The phenomenon is described using key (hopefully standard) words and expressions to further clarify the situation. This can include height, speed and direction, intensity and trend. They can also reference another advisory product.

Report Totals for 2 days:

06/01/2004 42
Wednesday 06/02/2004 61


METAR (Meteorological Aviation Routine)

METARs are surface observations, and are generally automated but can be augmented or corrected manually. METARs have replaced North American Surface Aviation code. The purpose of METAR is to standardized surface aviation reports throughout the world. METAR reports have the following sequence:

  • Type of report - METAR, routine observation
    SPECI, special
  • Station Identifier - ICAO location ID
  • Date/Time - Day of month, hour, minute UTC
  • Report Modifiers - AUTO or COR, if required
  • Wind - Direction true degrees north/speed in knots
    • When applicable, gusts and direction variation will be included.
  • Visibility reported in statute miles
  • Atmospheric Phenomena
    • Precipitation and obstructions to vision.
    • This information can contain intensity, proximity, description, precipitation and obstruction to vision.
  • Sky conditions
    • This reports the amount of sky cover, cloud height in hundreds of feet
  • Temperature and Dew Point
    • Temperature and dew point are reported in two digits in whole degrees Celsius, separated by a solidus "/".
  • Altimeter
    • The altimeter setting is in inches of mercury coded in 4 digits preceded by an 'A'
  • Remarks
    • Automated, manual or plain language remarks that can augment
      a METAR.

Report Totals for 2 days:

06/01/2004 97,456
Wednesday 06/02/2004 96,730