The USAF's Air Education and Training Command (AETC) began developing the requirements for a replacement for the Northrop T-38 Talon as early as 2003.

[3][4][5] In the Fiscal 2013 budget proposal, the USAF suggested delaying the initial operating capability to FY2020 with the contract award not expected before FY2016.

[6] Shrinking budgets and the need to fund higher priority modernization projects pushed the full implementation of the yet-to-be-selected T-X aircraft to "fiscal year 2023 or 2024".

[13][14] One of the driving requirements for the new trainer will be to help prepare pilots for the increased complexity in some areas, particularly information management, that are a part of fifth generation jet fighters like the F-22 Raptor and the F-35 Lightning II.

With the T-X already invested in, making it a multirole combat and training plane could defray costs of developing a new attack jet that can operate efficiently in a low-threat environment.

[17] However, by 2016 the Air Force decided to pursue other aircraft to meet CAS requirements and not "dilute" the trainer program to support other missions.

[3] In January 2013, General Dynamics joined Alenia Aermacchi and signed a letter of intent (LOI) to compete jointly on the program.

On 22 February 2016, Raytheon announced it was replacing General Dynamics and going to head-up the bid in the US for the T-X program, as the primary contractor, teamed with Leonardo, Honeywell Aerospace, and CAE USA Inc.

[34] Lockheed Martin and Korea Aerospace Industries (KAI) proposed their T-50 Golden Eagle, which first flew in 2002, for the T-X program.

Referred to as the "T-X demonstrator aircraft", it adds to the T-50 airframe the ability for aerial refueling, embedded ground training systems, and a large area display in place of the five smaller screens.

Lockheed Martin's upgraded T-50A jet trainer successfully completed its first flight test in June 2016 in Sacheon, South Korea, a key milestone for the aircraft.

[42][43] Northrop Grumman with partners BAE Systems, L-3 Communications, and Rolls-Royce Holdings, initially had intentions of proposing an updated version of the Hawk T2/128 for the T-X program.

[45] However, in 2015, Northrop Grumman was no longer submitting the Hawk for T-X consideration, primarily due to airframe performance shortcomings with maneuvers such as high angle-of-attack and sustained accelerations, as well as concerns regarding affordability.

[46] On 19 August 2016 in Mojave, Northrop Grumman publicly revealed a model of its T-X concept powered by a single GE F404-102D engine.

[citation needed] The companies have formed the Freedom Aircraft Ventures LLC in Centennial, Colorado to develop a lightweight, all-composite trainer for the competition.

[51] Additionally, during the Farnborough 2014 Airshow, Textron representatives expressed significant interest in the T-X program, and indicated they were closely following the progression of the draft requirements.

[21] On 23 August 2014, Textron AirLand formally confirmed they would compete for the T-X trainer and modify the Scorpion to better fit the training requirements.