In 1978, the domestic airline National Airways Corporation (NAC) and its subsidiary Safe Air were merged into Air New Zealand to form a single national airline, further expanding the carrier's operations. As a result, NAC's Boeing 737 and Fokker F27 aircraft joined Air New Zealand's fleet alongside its DC-8 and DC-10 airliners. The merger also resulted in the airline having two IATA airline designators: TE from Air New Zealand and NZ from NAC. TE continued to be used for international flights and NZ for domestic flights until 1990, when international flights assumed the NZ code.