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