Ventilation shaft

The Tenth Doctor found a ventilation shaft in Area 51. Observing that "there's always a ventilation shaft", he claimed that there was always a way out of them, "apart from in Star Wars, of course." (TV: Dreamland)

Jack Harkness climbed through two miles of ventilation shafts aboard the Crucible. (TV: Journey's End)

Rose Tyler refered to the maintenance tunnels in Sanctuary Base 6 as ventilation shafts. John Jefferson, while appreciating the reference, explained that there was no ventilation and no air, having been designed for machines and not life forms. (TV: The Satan Pit)

Aboard the Game Station, the Daleks travelled in hover position between floors using the ventilation shafts. (TV: The Parting of the Ways)