Designed in response to NATO December 1953 competition for a tactical attack and support machine, designated "NBMR-1" ("N"ATO "B"asic "M"ilitary "R"equirement ? "1") , the Fiat G.91 responded in all respects to the required characteristics: capable of operating from makeshift and unprepared runways, it was endowed with good speed (the first prototype exceeded mach 1 at an altitude of 9,000 m [3]) and could carry loads offensive of at least 450 kg. The creation of the first example took place well in advance of its main competitors, also due to the choice made by Fiat to base the project (on a smaller scale) on that of the F-86 Saber which the Turin company built under license [ 3]. The resulting similarity, in addition to arousing protests from competing companies in the NATO tender [1], earned the G.91 the nickname of small Sabre. The prototype was flown for the first time on 9 August 1956 at Turin-Caselle airport under the command of test pilot Riccardo Bignamini. Despite the extremely comforting initial results, problems abounded: only a week later, during low-altitude tests, aerodynamic problems arose (specifically, phenomena known as flutter arose) which caused the failure of the empennage and the consequent loss of the prototype. In January 1958, the G.91 was officially declared the winner of the competition, after overcoming a large group of opponents (7 in all), including the Breguet Br 1001 Taon, the Dassault Mystère XXVI (which later became Étendard VI), the Folland Gnat and the Aerfer Sagittarius 2[1]. The pre-series specimens equipped (starting from August of the same year) the 103rd Group (at the time part of the 5th Air Brigade) which tested their characteristics during operational missions. The following summer these specimens were subjected to the careful examination of a NATO commission which, also on this occasion, had to issue an extremely positive judgment.