Anti-gravity spiral

An Anti-gravity spiral was a projectable beam used for removing gravity from an object. The Seventh Doctor used his TARDIS to project a beam around a bus in space after it crashed. He manoeuvred it down to Earth and dropped it outside Shangri-La camp in southern Wales. The Doctor told Murray that he used the TARDIS vortex drive to generate the spiral. (DW: Delta and the Bannermen)