I am line editing a book about World War II and the Battle of the Coral Sea. The action is taking place in the front and rear cockpits of a Devastator torpedo-bomber aircraft. The pilot and gunner dropped a torpedo and have lost contact with the rest of the squadron.
There are two lines:
"The signal on the Zibby is dead." "The radio's dead, too."
So ... the Zibby is not the radio. Is it the torpedo's signal? Or is it some other communication device?
The author doesn't know, having created the manuscript from a now-deceased relative's journals.
My online searches for Navy aircraft torpedo pilot (etc.) slang has been unsuccessful.
== Additional information ==
The are trying to return to the aircraft carrier. No Zibby and no radio, so they are using the plotting board with its mechanical nautical(?) compass as a last resort.