[4][5] Being based on the S.211, the M-311 featured an advanced new cockpit, various structural enhancements (including the increased use of composite materials) and a new powerplant in the form of the Pratt & Whitney Canada JT15D-5C turbofan engine.

[6] The changes allowed for an extended fatigue life of 15,000 flight hours, increased intervals between overhauls and a reduced turnaround time between sorties.

By September of that year, the prototype had reportedly flown 30 flights, and was set to receive software upgrades to enhance its cockpit displays.

[2] During October 2014, it was announced that the Williams International FJ44-4M turbofan engine had been selected to power the in-development trainer, having overcome rivaling bids from both Honeywell and Pratt & Whitney.

[12] The company stated that Williams' engine has been selected due to its performance in the business aviation sector and with the Swedish Air Force's re-engined fleet of Saab 105 trainers.

Shortly thereafter, Alenia Aermacchi began installing the 3,400 lb-thrust FJ44-4M onto its flight-test aircraft, replacing the existing P&W Canada JT15D units.

[12] In March 2015, Alenia and ENAER of Chile signed a memorandum of understanding, to explore the possibility of jointly manufacture and sell the M-345 HET in South America.

[16] The first production-standard M-345 was flown from Venegono Superiore in December 2018; at this point, service entry with the Italian Air Force was anticipated to occur during 2020.

[19] Conventional ailerons are hydraulically boosted, with provisions for manual reversion, while both the elevator and rudder are mechanically actuated via pushrods, with three-axis electrical trimming.

The service has a requirement for up to 45 aircraft to replace Aermacchi MB-339s used in both the basic training role and by the Frecce Tricolori aerobatic team.

[23] During January 2021, the IAF inducted its first pair of M-345 trainers; the type will replace the MB-339A as the service's second and third phases of its pilot training programme.