It's probably less of an issue on larger/more modern planes where your squawk code is entered with a numeric pad - but on older/less complex planes you have to

It's probably less of an issue on larger/more modern planes where your squawk code is entered with a numeric pad - but on older/less complex planes you have to switch off the transponder when changing codes since it's a series of rotary dials and you don't want to accidentally broadcast an emergency code (7500/7600/7700) even for a second as it would trigger all sorts of alerts for the controller.