As GA pilots become increasingly dependent on GPS signals not only for navigation but for instrument approaches, it now appears that it may be possible for the signals to be disrupted by solar flares. Right now that's not a problem because the sun is in a quiet phase, but it's expected to get active again in 2011. That seems a long way off, but it will be here before you know it. The intense solar flares could cause GPS signals used by aircraft navigation and emergency location systems to degrade by up to 90 percent, for hours at a time. GPS has become ubiquitous during a quiet solar period, and no easy fix for the problem is immediately apparent. The disruptive effect was discovered accidentally by a grad student studying the ionosphere, and was later verified by numerous sources. So far, it seems the only way to cope with the interference is to have a backup plan for when it happens.