Lateral balance cones

Lateral balance cones were components of a Type 40 TARDIS.

One of the Fifth Doctor's attempts to get Tegan back to Heathrow Airport in 1981 was unsuccessful because the lateral balance cones were "playing up". This caused the TARDIS to land in the right place, but three centuries too early. (TV: The Visitation)

When the lateral balance cones went offline on another trip, the Fifth Doctor landed in 2008 Hove instead of 1818 Brighton. (AUDIO: Cuddlesome)