Clearing the Air on G-AIRMETClearing the Air on G-AIRMET
Ryan Solomon
and
Gregory Harris
Aviation Weather Center
IntroductionIntroduction
• In March 2010 the G-AIRMET became a “Primary” Operational Weather Product
• The FAA designation allows pilots and weather briefers to use G-AIRMETs as a primary decision making tool for anticipating and avoiding weather hazardous to safe flight operations
• The Graphical Airman’s Meteorological Advisory (G-AIRMET) has been operationally produced as a “supplementary” product since October 2008
TopicsTopics• How it began
• Evolution
• Safety
• Definition
• Depiction
• Difference from text AIRMET
• Available formats
• Where to get it
How it beganHow it began
• G-AIRMET is the collective response from the Federal Aviation Administration (FAA) and the National Weather Service to answer that call
• A “call” began to be heard from the users of the National Airspace System for higher resolution weather hazard information
• Text-based forecasts made logical sense 20 or more years ago, when teletype and facsimile were the primary methods of transmitting weather to pilots
EvolutionEvolution
• First software prototype released to forecasters in 2003
• Idea to change to a graphical forecast process was born in 2000
• Operational production of the G-AIRMET as a supplementary product began in 2008
• G-AIRMET becomes a primary product in 2010
SafetySafety
• G-AIRMET thoroughly scrutinized by a FAA Safety Risk Management Assessment Team (including controllers, dispatchers, pilots, and meteorologists)
• Team identified potential risks and implemented mitigation measures
– Removal of the AIRMET VOR Plot on websites (had potential to confuse users)
DefinitionDefinition
The Graphical AIRMET is:
• A graphical forecast of en-route weather hazards
• A series of snapshots at 3 hour intervals valid for up to 12 hours
00 hour represents the initial conditions
the subsequent 3-hourly graphics depict the area affected by the particular hazard at that valid time
• Routinely issued every 6 hours
• Updated as needed
DepictionDepiction
G-AIRMETs depict the following en-route aviation weather hazards:
• Instrument flight rule conditions (IFR)
• Mountain Obscuration
• Turbulence
• Low Level Wind Shear (LLWS)
• Strong Sustained Surface Winds
• Icing
• Freezing Level
G-AIRMET SierraG-AIRMET Sierra
Weather Hazard G-AIRMET Criteria/Depiction
Surface Visibility ≤3 miles (IFR)
Cause of Surface Visibility restriction
Precipitation (PCPN), Mist (BR), Fog (FG), Haze (HZ), Smoke (FU), Blowing
Snow (BLSN)
Low Ceilings Ceiling ≤1000 feet (IFR)
Mountain Obscuration Area
Cause of Mountain Obscuration
Clouds (CLDS), Precipitation (PCPN),Mist (BR), Fog (FG), Haze (HZ),
Smoke (FU)
G-AIRMET TangoG-AIRMET Tango
Weather Hazard G-AIRMET Criteria/Depiction
Turbulence Moderate, Surface to 40,000 feet
Sustained Surface Winds
≥ 30 knots
Low Level Wind Shear Wind shear (+/-10 knots) below 2000 feet
AGL
G-AIRMET ZuluG-AIRMET Zulu
Weather Hazard G-AIRMET Criteria/Depiction
Icing (non-convective)Moderate Airframe Icing
Surface to 45,000 feet
Freezing LevelLocation of the freezing level at the
Surface, 4,000, 8,000, 12,000, and 16,000 feet
Multiple Freezing Levels Area and vertical range
Differences from Text AIRMETDifferences from Text AIRMET
F00
F00
Aerial Coverage
Depth
F03
F03
F06
F06
G-AIRMET Snapshots Area of Text AIRMET
F00 F03 F06 =+ + 6HR Smear
This example shows a 00hr through 06hr G-AIRMET icing forecast for the Western U.S.- The G-AIRMET detail provides greater aerial and depth detail vs. the final Legacy AIRMET- The western edge of the G-AIRMET depicts a shallower icing layer depth, this detail is not correlated in the Text.
WAUS45 KKCI 081445 SLCZ WA 081445 AIRMET ZULU UPDT 3 FOR ICE AND FRZLVL VALID UNTIL 082100 AIRMET ICE...ID MT UT WA OR FROM 80ESE YDC TO 60NW GGW TO 40WSW LWT TO 20S MLD TO 20ESE REO TO 80ESE YDC MOD ICE BLW FL180.
Differences from Text AIRMETDifferences from Text AIRMET
G-AIRMET FormatsG-AIRMET Formats
• BUFR “Binary Universal Form for the Representation of Meteorological Data”
Allows users to customize displays
• GIF “Graphics Interchangeable Format (GIF)” images
• JAVA display Allows looping, overlaying, and zooming
• Coming Soon ... GIS based products
G-AIRMET on the WebG-AIRMET on the Web
AviationWeather.gov Advisories
SIGMET/AIRMET• Java Tool• US (CONUS)• AWC OceanicGraphical AIRMET
Graphical AIRMETGraphical AIRMETInteractive G-AIRMET page allows the user to select:
- Individual or multiple hazards
- Display the time of interest
- Loop the entire set
- View Static G-AIRMET Images
- View (CONUS) Text AIRMETs
Graphical AIRMETGraphical AIRMET
Text AIRMETsText AIRMETsPreviously we clicked theText AIRMET link. To view the Text AIRMETs:1. Click on the type of
hazard.2. Click on the area
desired.3. Click on the Retrieve
button.
4. The Text AIRMET will be retrieved in that same window.5. Click link on top of the page to select another Text AIRMET
AWC US(CONUS) PageAWC US(CONUS) Page
Provides “one-stop” shop for:G-AIRMET (Interactive and Static Displays, AIR/SIGMET Java Tool & Oceanic SIGMET
Text AIRMETs / SIGMETs
Displays Currently Active SIGMETs with individual links to each possible SIGMET category
http://aviationweather.gov/adds/
Static G-AIRMETStatic G-AIRMET
G-AIRMET SummaryG-AIRMET Summary
No change to text AIRMET
Improves temporal and spatial forecast resolution
Provided in three formats – BUFR, Java, GIF
Allows pilots to maintain high safety margins while flying more efficient routes