Nice work getting (almost?) all of the units going to this response! I like that you included the scanner traffic as well - I know it's a lot more work, but I think it adds a lot to the video.
Thanks for watching! 'B' stands for Battalion, which is a command unit. They're staffed by a firefighter at the rank of battalion chief, who as a pretty senior member isn't really fighting fires but more overseeing the operations of the ladder trucks, fire engines, etc. They respond to large incidents such as structure fires and extrications to command the scene. Each battalion chief is essentially the shift supervisor for 1/5 of the department (there are five battalion chiefs for each shift) 'M' stands for Medic, which is one of two types of ambulances in Seattle. 'A' stands for Aid, which is one type staffed by firefighters. They treat stable patients only and rarely transport, since SFD has a contract with AMR to transport stable patients. 'M' stands for Medic, which is staffed by paramedics. They're also firefighters, but when they're on the medic units, they only act as paramedics. They treat and transport the more seriously ill or injured patients. Hope this helped!
