In air trafc control (ATC), teamwork is a key component among air trafc control operators (ATCOs) to safely direct the aircraft through the sky and on the ground. To be able to design for future ATC systems, we must understand how ATCOs work together, their teamwork, and how they experience and perceive teamwork, in diferent ATC environments. We conducted interviews with 16 ATCOs working in four diferent ATC environments (en-route control, terminal area control, tower control for a small airport and tower control for a large airport in Sweden) and analysed the results in the light of the “Big Five” model of teamwork. The main contributions of this paper are to show: (1) how eight teamwork factors are diferently manifested by the ATCOs in the diferent ATC environments, (2) that teamwork in ATC is important during routine operations, during stressful work, and during abnormal situations, and (3) that the design of the organisation, the environment, and the tools, afects teamwork and the importance of diferent teamwork factors.