flight-test G600s accumulated 1,950 hours in 510 flights, were completing mechanical systems certification testing in May 2018 before airfield-performance testing in summer. By August, 600 flights over 2,290 hours were completed after trials for ice shapes and stall speed testing and before field-performance testing, towards U.S. approval by year-end and deliveries in 2019. By October, the test aircraft had accumulated 685 flights in over 2,600 hours. The FAA's rigorous review delayed the certification as the test programme had logged more than 3,150h over 840 flights by the end of April 2019, and approval was targeted before the end of June for a second half of 2019 service entry. On June 28, 2019, Gulfstream announced the G600 type and production certificates from the FAA. The first G600 was delivered on August 8, 2019. The first EASA-certified G600 was delivered in December 2020 to an Austrian operator. In 2022, its equipped price was $59.5M. G400 On October 4, 2021, Gulfstream introduced the 4,200 nmi (7,780 km) range G400, powered by Pratt & Whitney PW812GA engines with deliveries planned to start in 2025. Priced at $34.5 million, the G400 has a shortened G500 fuselage, with 2.5 zones and 10 Windows, instead of 3 zones and 14 windows. By March 2022, as the prototype was not yet rolled out, Gulfstream was anticipating a more extensive flight-test and certification campaign for the five test aircraft, as the G400 is powered by a different PW800 variant and the US government strengthened some certification requirements after the Boeing 737 Max groundings, but the 2025 first delivery goal remained. Design The G500 will replace the G450, flying nearly faster and 18% farther with the same fuel burn. The larger G600 will succeed the G550. Airframe Both models have a four circular arcs cross-section fuselage, similar to the Gulfstream G650, with a reduction in width and height. Similar in dimension to the Dassault Falcon, the G500/600 have more headroom, more cabin width and more floor width than Gulfstream's G450 and G550. The fuselage has an external height of , and width of . The production G500 will have 14 windows, two more than the prototype models. The G600 cabin is longer than the G500, allowing up to four passenger zones or three long zones, a longer galley and a forward crew rest. The wing is a supercritical design with a 0.87 to 0.88 drag divergence Mach number depending upon