bogey ... one strike more than par on a golf hole
bogy or bogies ... imaginary evil being or spirit(s)
bogie or bogies ... low swiveled undercarriage at either end of railroad car
Bogey ... Humphrey Bogart
The second meaning of bogy or bogies is most appropriate for air war: anything one especially, and often unneedlessly, fears
No matter how it's spelled in air war, bogy/bogey/bogie/bogies means heads up.
At least we never see it spelled boggy, boggys, or bogeys.