Back during the mid to late sixties, I heard perhaps 3 or 4 of those solar flare noise showers on 15 meters that completely took out the band for about 2 minutes. I have witnessed other flares that made all the bands go totally dead, signals fading into nothingness, and 15 to 20 minutes later, everything peaking back up again. One of this was during Field Day back in the lat sixties and I was on 20 meter side band when it happened.
Phil.
K0NX