Definition
An in-flight weather advisory issued by the National Weather Service warning of weather phenomena that may affect aircraft safety but are less severe than those described in a SIGMET. AIRMETs cover moderate icing, moderate turbulence, sustained surface winds of 30 knots or more, widespread areas of ceilings less than 1,000 feet and/or visibility less than 3 miles, and extensive mountain obscurement. They are of particular concern to pilots of light aircraft and to all pilots operating without instrument qualifications or equipment.
Plain English
A weather alert sent out during the day to warn pilots about widespread weather that could be dangerous, especially for smaller aircraft, but isn't extreme enough to be a top-tier warning.
Context Anchor
Pilots see AIRMETs during preflight weather planning and in aviation weather briefings before or during a flight.
Derivation
Formed from 'Airmen's Meteorological Information.' 'Meteorological' comes from the Greek 'meteoron,' meaning 'thing high up,' which is the root of meteorology — the study of the atmosphere. The acronym signals that this is weather information aimed specifically at pilots in flight.
Why Pilots Care
Allows pilots to anticipate and avoid weather that could be challenging for their aircraft.
Intuition Check
An AIRMET is not a report that the bad weather is at one exact point. It is an advisory that a broad area may contain conditions pilots need to plan around.
Example Sentence 1
During his preflight briefing, the pilot noted an AIRMET for moderate icing between 6,000 and 12,000 feet and chose to file at a lower altitude.
Example Sentence 2
During the preflight briefing, the AIRMET for low ceilings prompted a delay until conditions improved.