Definition
A snowflake icon printed next to an airport name on instrument approach charts and in the Chart Supplement, indicating that the airport has published cold temperature restricted altitudes. When the reported airport temperature is at or below the published trigger temperature, pilots must apply a cold temperature altitude correction to one or more designated segments of the approach.
Plain English
A small snowflake printed next to an airport's name that warns pilots: when it gets cold enough here, you need to add altitude to parts of the approach because cold air makes the altimeter read higher than you actually are.
Context Anchor
Seen on FAA instrument approach charts in notes related to hot and cold temperature limitations.
Derivation
A snowflake is the familiar ice-crystal shape used to represent cold weather. On an approach chart, that familiar cold-weather symbol is used as a quick visual warning that temperature may affect safe altitude use.
Why Pilots Care
Alerts the pilot that failure to apply the required cold temperature corrections can result in descent below published altitudes and reduced terrain or obstacle clearance.
Grounding Statement
The colder the air is, the more important it is to check whether the published approach altitudes need to be raised for safety.
Intuition Check
The snowflake symbol is not a weather forecast and does not mean icing is present. Here, it is a chart warning to check cold-temperature altitude corrections.
Example Sentence 1
Briefing the approach into Bozeman, the captain pointed to the snowflake symbol next to the airport name and reminded the first officer to check the trigger temperature before deciding whether a cold temperature correction was required.
Example Sentence 2
With the snowflake symbol present, the crew consulted the cold temperature correction table before beginning the approach.