Page "RAF North Witham" Paragraph 18

IX Troop Carrier Command groups selected three crews each for training, and trained on school C-47s fitted with " Gee " radar triangulation navigational equipment and a limited number of SCR-717-C search radar sets.

" Rebecca " ( AN / APN-2 ) interrogators were also installed to query " Eureka " ( ANIPPN-l ) transponders, the ground set which was used to mark the landing or dropping zones during an airborne operation, the combination Rebecca / Eureka transponding radar system used as a homing beacon.

The pathfinder air crews worked with teams drawn from paratroop regiments, the task being to locate a given dropping point with a combination of Gee and SCR-717-C, drop the paratroops who would then set up Eureka sets and visual aids on the ground to guide in the main airborne force to within an optimum visual range for an accurate delivery.