Aviation Colour Codes are based on four colours and are only intended for use by the international Civil Aviation community. Unlike the New Zealand Volcanic Alert Levels, they do not provide information about the impact of volcanic activity on the ground, in the air, or near the volcano. Instead, they provide the aviation sector with some general awareness of volcanic activity and potential presence of volcanic ash in the atmosphere. This information enables the aviation sector to make decisions about aviation safety and flight routes, especially for long-haul flights.
Example: ACC Code Orange indicates that a volcanic eruption is underway but with little or no ash being produced
|ICAO Colour Code||Status of activity of volcano|
|GREEN||Volcano is in normal, non-eruptive state. or, after a change from a higher level: Volcanic activity considered to have ceased, and volcano reverted to its normal, non-eruptive state.|
|YELLOW||Volcano is experiencing signs of elevated unrest above known background levels. or, after a change from higher alert level : Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.|
|ORANGE||Volcano is exhibiting heightened unrest with increased likelihood of eruption. or, Volcanic eruption is underway with no or minor ash emission. [specify ash-plume height if possible].|
|RED||Eruption is forecasted to be imminent with significant emission of ash into the atmosphere likely. or, Eruption is underway with significant emission of ash into the atmosphere. [specify ash-plume height if possible].|