After the September 11 terrorist attacks, Mesaba was forced to reduce its workforce by 400 employees to achieve cost savings. In the fall of 2003, Northwest wanted to retire the Avro jet fleet, which comprised about half of Mesaba's revenue. They were inefficient and aging, according to Northwest. However, Mesaba was able to negotiate a deal with Northwest which enabled the Avro fleet to remain in service. In 2005, Mesaba began receiving fifteen new Canadair CRJ regional jets that would eventually replace the larger Avro jets.