Smallest orbit separation, Δ_min, between any planet pair changes with inclination and position angle. We indicate the inclination and position angle of the HR 8799 system measured by Matthews et al. (2014) with a white square (simulation 2), which is i = 26 ± 3° and position angle 64 ± 3°. The largest Δ_min occurs at i = 25° and position angle 42°, when Δ_min = 3.56R_H. This value is indicated with a filled, white circle (simulation 3). This plot is based on the observations from Marois et al. (2008, 2010).