 By 1985 America West had outgrown their gate space at Phoenix Sky Harbor International Airport, and during the construction of Terminal 4, approved in 1986, a temporary concourse was added to the southwest corner of Terminal 3 to give them six more gates (growing to eleven by 1990).The airline's growth continued in 1986, and the airline expanded its fleet, mainly with Boeing 757-200s purchased from Northwest Airlines (following Northwest's acquisition of Republic Airlines) and a number of de Havilland Canada DHC-8 Dash 8s.