The KP index monitors the particle radiation which hits the earth an affects its magnetic field. The scale has a range from 1 to 9 of which 1-3 (green) and 4 (yellow) express only slight deviations from the normal magnetic field. A value of 5 or higher is marked red and means critical influence on the precise determination of the GPS position combined with a magnetic compass.

Multirotor flight control systems can be disturbed significantly by a KP of 5 or higher, which can lead to unforeseeable flight manoevers.

Please refrain from using systems with GPS or compass support during the red KP phase.

More information: www.swpc.noaa.gov/products/planetary-k-index