FAA · Information for Operators (InFO)
InFO 18011: Updated Coding Requirements for Snow Pellets and Small Hail
In Brief
What It Addresses
This InFO provides information on updated coding requirements for reporting snow pellets and small hail in Meteorological Terminal Aviation Routine Weather Reports (METAR).
Why It Matters
Currently, snow pellets and/or small hail have a single code of “GS” being used to report two different precipitation types, which also requires a weather observer to augment the METAR or Aviation Special Weather Report (SPECI). This has often resulted in flight-crews being unable to interpret holdover time limitations.
Recommended Action
Pilots and dispatchers should familiarize themselves with the information contained in this InFO.
From the Document: selected source passages, quoted as written, for a quick overview.
Distributed by: Air Transportation Division
http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/info An InFO contains valuable information for operators that should help them meet certain administrative, regulatory, or operational requirements with relatively low urgency or impact on safety.
Subject: Updated Coding Requirements for Snow Pellets and Small Hail
Purpose: This InFO provides information on updated coding requirements for reporting snow pellets and small hail in Meteorological Terminal Aviation Routine Weather Reports (METAR).
Background: Currently, snow pellets and/or small hail have a single code of “GS” being used to report two different precipitation types, which also requires a weather observer to augment the METAR or Aviation Special Weather Report (SPECI). This has often resulted in flight-crews being unable to interpret holdover time limitations.
Per Federal Aviation Administration (FAA) Notice 8900.275 (Winter 2014-2015) small hail has been determined to be meteorologically equivalent to moderate ice pellets for anti/de-icing purposes. Airlines for America (A4A) made a request to the Office of the Federal Coordinator for Meteorology to change the reporting of small hail from “GS” to ice pellets (PL) in Federal Meteorological Handbook No. 1 in August 2014. This request was forwarded to the FAA, and after evaluating the A4A proposal and other options, an agreement was reached to report small hail as “GR” and snow pellets as “GS.”
Discussion: The driver for the change in the current coding of snow pellets and small hail was the need to clarify precipitation type, which would allow flight-crews to apply the appropriate Allowance Times or Holdover Times in order to improve the efficiency of deicing/anti-icing operations. Small hail and moderate ice pellets have been deemed meteorologically equivalent and have the same allowance times for anti-icing/deicing procedures (FAA Holdover Time Guidelines Winter 2018-2019, Table 39). The first change will be the use of “GR” to refer to all hail. All reports of hail must include hailstone size diameter in the remarks section of the METAR/SPECI in increments of ¼ inches.
When small hail less than ¼ inch in size is occurring, the hailstone size is reported in the remarks as, “GR LESS THAN ¼ inch.” Small hail will also result in issuance of a SPECI. Aircraft are not permitted to operate in large hail, however, can operate in small hail with deicing/anti-icing procedures.
The second change will reflect “GS” for snow pellets only when observed and will have appropriate holdover times (FAA Holdover Time Guidelines Winter 2018-2019, Table 28). These changes will:
Solve operators’ de-icing issues;
InFOInformation for Operators
U.S. Department
of Transportation
Federal Aviation
Administration
InFO 18011
DATE: 10/10/18
Flight Standards Service
Washington, DC
Distributed by: Air Transportation Division
Provide a single code for ALL hail regardless of size; and
Preserve the climate record.
Recommended Action: Pilots and dispatchers should familiarize themselves with the information contained in this InFO.
Contact: Questions or comments regarding this InFO should be directed to the Flight Technologies and Procedures Division, at (202) 267-8790.
Source: Federal Aviation Administration — www.faa.gov. Reproduced from the published record; FlightPush adds formatting only.
InFO 18011