Cessna Aircraft last month announced the introduction of wide-area augmentation system (Waas) avionics upgrades for the Citation CJ1+, CJ2+, CJ3 and Encore+ as well as certain Citation Excel and XLS airplanes. Cessna has obtained a service bulletin for the installations in the CJ models and Encore+. Waas can be added to Excel and XLS models equipped with the Universal Avionics UNS-1Espw flight management system. The modifications are now available at any of Cessna’s nine factory-owned Citation service centers. Waas improves GPS signal accuracy and permits properly equipped aircraft to fly Waas LPV (lateral precision with vertical guidance) approaches, which have landing minimums similar to Category I ILS.