AIM 7-1-2 FAA Weather Services
Chapter 7. Safety of Flight · Section 1. Meteorology
A reference copy of the official AIM text for study. It is not legal advice or an FAA interpretation; always confirm against the current official source.
a. The FAA provides the Flight Service program, which serves the weather needs of pilots through its flight service stations (FSS). Pilots may access weather information through www.1800wxbrief.com. To contact Flight Service in the CONUS, Hawaii, and U.S. territories; call 1-800-WX-BRIEF (1-800-992-7433); in Alaska call 1-833-AK-BRIEF (1-833-252-7433).
b. The FAA maintains an extensive surface weather observing program. Airport observations (METAR and SPECI) in the U.S. are provided by automated observing systems. Various levels of human oversight of the METAR and SPECI reports and augmentation may be provided at select larger airports by either government or contract personnel qualified to report specified weather elements that cannot be detected by the automated observing system. The requirements to issue SPECI reports are detailed in TBL 7-1-1.
SPECI Issuance Table
| 1 | Wind Shift | Wind direction changes by 45° or more, in less than 15 minutes, and the wind speed is 10 kt or more throughout the wind shift. |
|---|---|---|
2 | Visibility | The surface visibility (as reported in the body of the report): • Decreases to less than 3 sm, 2 sm, 1 sm, ½ sm, ¼ sm or the lowest standard instrument approach procedure (IAP) minimum. 1 • Increases to equal to or exceed 3 sm, 2 sm, 1 sm, ½ sm, ¼ sm or the lowest standard IAP minimum. 1 1 As published in the U.S. Terminal Procedures. If none published, use ½ sm. |
3 | RVR | The highest value from the designated RVR runway decreases to less than 2,400 ft during the preceding 10 minutes or, if the RVR is below 2,400 ft, increases to equal to or exceed 2,400 ft during the preceding 10 minutes. U.S. military stations may not report a SPECI based on RVR. |
4 | Tornado, Funnel Cloud, or Waterspout | • Is observed. • Disappears from sight or ends. |
5 | Thunderstorm | • Begins (a SPECI is not required to report the beginning of a new thunderstorm if one is currently reported). • Ends. |
6 | Precipitation | • Hail begins or ends. • Freezing precipitation begins, ends, or changes intensity. • Ice pellets begin, end, or change intensity. • Snow begins, ends, or changes intensity. |
7 | Squalls | When a squall occurs. (Wind speed suddenly increases by at least 16 knots and is sustained at 22 knots or more for at least one minute.) |
8 | Ceiling | The ceiling changes 1 through: • 3,000 ft. • 1,500 ft. • 1,000 ft. • 500 ft. • The lowest standard IAP minimum. 2 1 “Ceiling change” means that it forms, dissipates below, decreases to less than, or, if below, increases to equal or exceed the values listed. 2 As published in the U.S. Terminal Procedures. If none published, use 200 ft. |
9 | Sky Condition | A layer of clouds or obscurations aloft is present below 1,000 ft and no layer aloft was reported below 1,000 ft in the preceding METAR or SPECI. |
10 | Volcanic Eruption | When an eruption is first noted. |
11 | Aircraft Mishap | Upon notification of an aircraft mishap, 1 unless there has been an intervening observation. 1 “Aircraft mishap” is an inclusive term to denote the occurrence of an aircraft accident or incident. |
12 | Miscellaneous | Any other meteorological situation designated by the responsible agency of which, in the opinion of the observer, is critical. |
c. Other Sources of Weather Information
1. Weather and aeronautical information are available from numerous private industry sources on an individual or contract pay basis.Prior to every flight, pilots should gather all information vital to the nature of the flight. Pilots can receive a regulatory compliant briefing without contacting Flight Service. Pilots are encouraged to use automated resources and review AC 91-92, Pilot's Guide to a Preflight Briefing, for more information.
2. Pilots can access Leidos Flight Services via the Internet at http://www.1800wxbrief.com. Pilots can receive preflight weather data and file VFR and IFR flight plans.