Southwest does not use AT and Vnav. We fly Cat IIIa approaches hand flown with the HGS (Heads-up Guidance System - HUD) to DH of 50 feet. RVR 700 feet. When flying with the A/P we either use the V/S, LVL Change or just fly it like CWS. The A/P captures the altitude, no need to select Alt Hold. We must be doing something right we are still making money.
