Pilatus announced it was developing the PC-12 at the National Business Aircraft Association's annual convention in October 1989. First flight of the first of two prototypes occurred on May 31 1991. Certification was originally planned for mid 1993 but a redesign of the wings with the addition of winglets to ensure performance guarantees were met pushed this back, with Swiss certification awarded on March 30 1994 and US FAA FAR Part 23 approval following on July 15 1994.