Players: United Airlines would be a player in this as they have a high interest in what their customers think about them, and they have the power to do something about it.
Context Setters: Employees of United Airlines would be the context setters as they have some power in how to treat the customers but they probably don’t have a lot of interest in it as it’s not their company and it’s not really affecting their pay.
Subjects: Other passengers would be subjects as they have a high interest in how airlines treat their customers, but they don’t have much power in changing that. Other airlines would also be subjects as they want to know what customers think about their competition.
Crowd: the crowd would be people that follow this persons Instagram but maybe don’t travel often and don’t care about airlines.