Barberpole is a phrase used to describe the striped output of indicators used during the Apollo and Shuttle programs. Typically an indicator was positioned below a switch. When the switch was activated and the activation indeed performed, the resulted activation was talked back via a separated electrical line to the barberpole indicator to show a grey and white striped pattern, thus verifying the action to the astronaut. Such switches with barberpole indicators were called talkback switches. Various indicators in the Apollo Command Modules indicated barberpole when the corresponding system was inactive. Astronaut Jim Lovell can also be found describing system indications as "barber poled" in the transcript of radio transmissions during the Apollo 13 accident.
