May 18, 2011— -- United Airlines stopped using the flight numbers 93 and 175 after its planes with those flight numbers were used in the terrorist attacks on the United States on Sept. 11, 2001.

Former Student Pilots Sue United Airlines' Aviate Academy Over Fraud Allegations. ... United decided to start its own flight school in 2022 with the aim of training about 5,000 new pilots by 2030.