First row: Number of BBF footpoint-Swarm conjunctions for different time and MLAT position error (Δt, ±Err_MLAT, respectively) for the Northern Hemisphere and each Swarm satellite. The number inside each bin is the total number of conjunctions, and the color is the percentage with respect to the total number of BBFs. Second row: Percentage of conjunctions with $Q_{\mathrm{fp}}^{\mathrm{stat}}=1$ (the footpoint distance computed with the T89 and TA15n models is lower ±1 h in MLT and ±4° in MLAT) and Q_cj = 1 (Swarm satellite passing through two different footpoints). Third row: Similar to second row but with $Q_{\mathrm{fp}}^{\mathrm{phys}}=1$ (the footpoint distance computed with the T89 and TA15n models is lower ±0.3 h in MLT and ±0.81° in MLAT). Column (a) BBF conjunctions with Swarm A. Column (b) BBF conjunctions with Swarm B. Column (c) BBF conjunctions with Swarm C.