Lingering technical issues are forcing Garmin to delay plans for upgraded WAAS capability in its GNS 430/530 and GPS 400/500 panel-mount avionics, according to a spokesman. Explaining that the upgrades will require “a major software rewrite” in addition to minor hardware changes, the spokesman indicated that the capability is now not expected to be available before next year’s third quarter. WAAS is an FAA-run satellite and ground station network designed to improve the accuracy of GPS satellite signals.