The National Labor Relations Board backed Boeing’s challenge to a unionization vote by a group of 176 flight line inspectors and technicians at its North Charleston, South Carolina complex.

The employees voted nearly 2-to-1 in May 2018 to join the International Association of Machinists, but Boeing contended the group was not distinct enough from the plant’s 2,700 other workers to organize separately.

Although a regional NLRB official had backed the union, the full board sided with Boeing.