Inner working angle (IWA) as a function of the PA-averaged projected baseline length $\alpha \cdot B/\left|\alpha \right|=\left|B\right|/\sqrt{2}$. For very long baseline lengths, the IWA is limited by telescope diffraction, approaching one λ/D. However, for most of the VLTI baselines, the IWA is typically limited to several λ/D. The addition of a new telescope would create four new baselines with an IWA only limited by the 8-metre telescope diameter.