The Portuguese civil aviation pilots' union (SPAC) has issued a stark warning against Lufthansa's potential entry into TAP Air Portugal's capital, citing concerns over the German group's labour practices and the risk they pose to social peace and operational stability at Lisbon's hub. As the privatisation of TAP enters a decisive phase, SPAC sent a letter to the government denouncing what it calls Lufthansa's 'anti-union' culture, pointing to ongoing conflicts with German pilot union Vereinigung Cockpit (VC) and the accelerated closure of regional subsidiary CityLine. The Portuguese government is selling up to 49.9% of TAP, with 5% reserved for employees and the industrial partner limited to 44.9%. Conditions include maintaining Lisbon as the main hub and preserving strategic routes to Brazil, Portuguese-speaking Africa, and North America. After a pre-qualification phase, Air France-KLM and Lufthansa submitted detailed non-binding bids by the April 2 deadline, while IAG (British Airways/Iberia) withdrew, preferring majority control. SPAC does not oppose privatisation in principle but insists that any buyer must demonstrate solid technical, financial, and labour credentials. The union's main grievance is Lufthansa's recent unilateral termination of an agreement governing union activity days for pilot representatives in Germany, which SPAC describes as 'union busting'. It also cites the abrupt closure of Lufthansa CityLine, blaming fuel price spikes and social unrest, as a sign of the group's aggressive restructuring approach. For ATPL and ATC students, this case illustrates how industrial relations and corporate strategy directly impact network planning, hub operations, and crew working conditions. Understanding the dynamics between flag carriers, unions, and government stakeholders is essential for future aviation professionals who will operate within these complex environments.