Air Traffic Control and Bandboxing

Many of you are perhaps familiar with 'bandboxing' in air traffic control circles, for those that are not familiar with the term it basically means a controller is working more than one sector and/or frequency at a time.

Remember these? An early digital airband radio from Swinburne

For instance, the Daventry high sector for mainly northbound traffic over the east midlands uses 127.1 and the Daventry high sector for mainly southbound traffic over the west midlands uses 129.2. Now this morning (Sunday morning) traffic levels are lower and therefore one controller is working both sides of this sector and hence both aircraft and controller can be heard on both frequencies (transmissions re-transmitted on both frequencies). You may hear the controller on one frequency and the aircraft on another frequency.

This situation frequently occurs for me with Swanwick military central because I can always hear the controller on 252.875 UHF but if an aircraft is talking to him on his VHF frequency (128.7) I usually only hear the aircraft side of the conversation (probably different transmitter sites in use). 

Again, it can be down to a lot of factors such as your location and the location of any actual transmitter sites that 'repeat' the transmission from Swanwick etc.

But hopefully, that gives you an idea, I'm no radio 'tecchy' so would not even try to explain the more technical aspects of this!