https://phys.org/news/2018-07-solar-flares-disrupted-radio-september.html

On the surface of the Sun, 150 million kilometers (93 million miles) away, another storm was brewing. A class X-2.2 and major class X-9.3 solar flare erupted on the morning of September 6 at about 8 a.m. local time. NOAA's Space Weather Prediction Center warned of a strong radio blackout over most the sunlit side of Earth, including the Caribbean.

Amateur radio operators assisting with emergency communications in the islands reported to the Hurricane Watch Net that radio communications went down for most of the morning and early afternoon on September 6 because of the Sun's activity, according to the new study. French civil aviation reported a 90-minute loss of communication with a cargo plane, according to the study's authors, and NOAA reported on September 14 that high frequency radio, used by aviation, maritime, ham radio, and other emergency bands, was unavailable for up to eight hours on September 6.