All of the air operations on a fire big or small are under the control of an single aerial attack supervisor. This individual has responsibility for both the fixed wing and helicopter resources. It is also up to the supervisor to determine if additional resources are needed or if they have as many as they can practically use. There is a very small group of specialists who have the knowledge and skills to do this job, believe me they all know each other and probably have worked together in the past.
I have had the pleasure of getting acquainted with one these individuals in the last couple of days, he just retired this year after a lifetime of doing this job all over the U.S., he is having a very difficult time getting his head wrapped around the fact that his health has forced him to retire. He told me this morning that he still fights wildfires in his head every night. This is the first season he will not be fighting fires since he came out of retirement in 1980!