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    "en": "Radio Blackout"
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    "en": "Radio blackout is a prolonged period of fading or faded radio communications, primarily in the high frequency range from ionospheric changes because of increased solar activity, in particular solar flares of C-class level or higher on the sunlit side of Earth (AMS, 2018). <br /> <p>AMS, 2018. <a href=\"https://glossary.ametsoc.org/wiki/Radio_blackout\"> Radio blackout. American Meteorological Society (AMS)</a>. Accessed 15 October 2020.</p>"
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      "Radio blackouts due to solar flares can last from minutes to hours. Solar proton events can also cause long-term radio blackouts over the polar regions for days; these are known as polar cap absorption events (PCAs). Radio blackouts due to solar flares of the M-class level and higher are classified using the NOAA R-Scale (AMS, 2018). Radio blackouts due to solar flares of the M-class level and higher are classified using the National Oceanic and Atmospheric Administration R-Scale (AMS, 2018). Solar flare intensities cover a large range and are classified in terms of peak emission in the 0.1–0.8 nm spectral band (soft X-rays) (NOAA, 2019). The X-ray flux levels start with the ‘A’ level (nominally starting at 10–8 W/m2). The next level, ten times higher, is the ‘B’ level (≥10–7 W/m2); followed by ‘C’ flares (10–6 W/m2), ‘M’ flares (10–5 W/m2), and finally ‘X’ flares (10–4 W/ m2). The UK Civil Aviation Authority reported that during moderate and above solar storms, high frequency communications on the sunlit side of the Earth are prejudiced through radio blackouts associated with sudden ionospheric disturbances due to the flare (UK CAA, 2020). They noted that at very high latitudes high frequency communications can be prejudiced as a consequence of the radiation storm which causes polar cap absorption, and at auroral latitudes rapid fading and further absorption can occur as a secondary effect associated with the geomagnetic storm. They reported that the various events can last for periods of minutes to hours. As a consequence, aircraft crossing the Atlantic have well established procedures for coping with a loss of high frequency communications which allows aircraft to continue their intended flight plan (UK CAA, 2020)."
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