Observational data in the radio, X-ray and optical wavebands provide the reliable evidences that the interaction between flare coronal loops can lead to the onset of solar flares.

During the 21st solar activity cycle the HXEBS aboard SMM satellite and the HXM on HINOTORI spacecraft detected several thousand hard X-ray solar flares.

The intensity of flares at X-ray wavelengths is a good indicator of the chance of a significant fadeout.