In a recent examination of modern-day "worker voice," Peter Ackers argued that declining membership density should impel trade unions to disavow outdated radicalism, embracing instead more "responsible" relations with employers, the state and the public. In professionalism, he maintained, trade unions might find greater public legitimacy and increased membership, by focussing upon "bread and butter" issues and occupational identity.1 In this historical case study, licensed aircraft maintenance engineers (LAMEs) did just this. They built an industrial strategy around the workplace power embodied in their licences and their regulatory oversight role within the maintenance labour process, claiming their technical expertise warranted greater professional recognition from operators. Rebuffing these overtures, some employers lobbied for regulatory changes that amounted to ill-disguised deskilling, in order to undermine growing industrial cohesion and confidence among engineers. Although the LAMEs' campaign against the changes was mostly successful, we suggest that their focus on professional status ultimately weakened their industrial position by emphasising their distinctiveness at the expense of solidarity with other aviation unions. We posit this interpretation as a contributing factor in the industrial disunity that plagues contemporary aviation unions.