FAA certification standards for Part 25 transport category aircraft and their jet and turboprop engines operating in icing conditions will change as of January 5, 2015. The changes will also create a number of new rules, such as Part 25.1324, which relates to angle-of-attack systems, and will specifically alter the way manufacturers prepare their products to encounter super-cooled large drop icing, as well as mixed-phase and ice-crystal conditions. The certification updates have been a long time coming, having first been suggested by the National Transportation Safety Board back in 1996 (following a loss-of-control accident involving an ATR 72 in freezing drizzle at Roselawn, Ind.). The new standards, however, will affect only new designs and are not intended to be retroactive. Noteworthy during the long wait for regulatory change are the updated training requirements created by the stick pusher and adverse weather event training aviation rulemaking committee formed in 2010. Other input came from the ice protection harmonization working group, which addressed new Part 121 operating procedures for aircraft in icing conditions, effective as of 2011.