Procedure or Politeness
Radio communication is a very important part of a pilots duties. There is specific protocol that needs to be followed in order for you to get your message across clearly in the shortest amount of time possible. Take a look at this example:
Controller: “American 1778, contact tower now on 122.8. Good day”
Aircraft: “Contact tower on 122.8, American 1778”
This is called a “hand-off”. This particular aircraft wants to land, and the controller knows this because of the flight plan that was filed before the flight took off from their origin. The controller started his transmission with the call sign of the aircraft, followed by the instruction. The aircraft wont execute the instruction until he’s read it back to the controller.
This is a pretty routine “radio transaction” between pilot and controller. The interesting part lies in the “Good day” portion of the controllers transmission. Some controllers say “Good day” or “Good evening”. Some even like to use “so long” or “cya!”.
I wasn’t able to find any official documentation that specifies that you have to say “good day” when you expect to no longer talk with the aircraft. So I wonder if this was something that controllers just started doing to let the pilots know that you don’t need to talk to them anymore.
Then there are some controllers who just love to have fun. In this particular clip, a ground controller from Boston slips in a few “go sox!” into his instructions.