Left-hand panel: model spectra for He I 6678 Å calculated in LTE (black curve) and NLTE (red and blue curve) for T_eff = 28000 K, log(g) = 5.60, and log(y) = −2.00. He I 6678 Å is clearly strongly affected by NLTE effects. While the red model is based on “old” Stark broadening tables for hydrogen and He I (Dimitrijevic & Sahal-Brechot 1990), the blue model uses “new” broadening tables from Beauchamp et al. (1997). Right-hand panel: same as the left-hand panel, but zoomed-in. The difference between the “old” (red curve) and “new” (blue curve) model is marginal, but sufficient in order to explain small deviations in atmospheric parameter determination (see Sect. 3.1 for details).