From The Merriam-Webster dictionary:
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Definition of
SCAB
1
: scabies of domestic animals
2
: a crust of hardened blood and serum over a wound
3
a : a contemptible person
b (1) : a worker who refuses to join a labor union
(2) : a union member who refuses to strike or returns to work before a strike has ended
(3) : a worker who accepts employment or replaces a union worker during a strike
(4) : one who works for less than union wages or on nonunion terms
4
: any of various bacterial or fungus diseases of plants characterized by crustaceous spots;
also : one of the spots
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While the common use of the word refers only to strike-breakers it's obvious the East pilots also fall under definitions 3a and possibly 4.
USAPA was formed for a very un-unionlike reason and the greatest beneficiary of USAPA has been USAirways management. If the shoe fits...