"On September 27, 2018, the United States Air Force (USAF) awarded The Boeing Company a contract, worth up to $9.2 billion, to procure 351 Advanced Pilot Training (APT T-X) aircraft and 46 Ground-Based Training Systems (GBTS) to replace the existing fleet of T-38C jet trainers. The Air Force had originally valued the contract at roughly $19.7 billion. Information on the value of other competitors' bids was not available. The FY2019 Administration budget request included $265.465 million for the T-X. According to the USAF, the T-38C trainer fleet is old, costly, and outdated, and lacks the technology to train future pilots for fifth-generation fighter and bomber operations. Based on Air Education Training Command's evaluation of the required capabilities to train future pilots for fifth-generation fighters and bombers, the T-38C falls short in 12 of 18 capabilities, forcing the USAF to train for those capabilities in operational units where flying hours are costly and can affect fleet readiness."
CRS Report for Congress, R44856
Congressional Research Service: https://crsreports.congress.gov/