Notes
Port of Seattle presentation on North Flow and South Flow noise abatement procedures at Seattle-Tacoma International Airport (Sea-Tac Airport), dated May 23, 2012. North Flow procedures specify daytime east turn at 8 NM and 4,000 ft or 5 NM and 4,000 ft; nighttime restrictions 10 p.m.–6 a.m. require Elliott Bay turn with no east turn, minimum 10,000 MSL or crossing the 323-degree radial; aircraft not to cross shoreline eastbound until intercepting the 223 radial above 10,000 ft; Puget Sound Departure North, Puget Sound Departure South, Duwamish/Elliott Bay Corridor, North Flow Initial Departure, and North Flow Arrivals Corridor. South Flow procedures require aircraft to fly straight out 5 nautical miles and 3,000 feet; east arrivals stay north of the 520 Bridge before turning south; aircraft stay west over sound arriving through Elliott Bay. Compliance data for 3/1/2012–3/31/2012 shows 89 out of 2,431 flights turned south of the 520 Bridge during daytime hours, broken down by airline including ASA (27%), SWA (18%), AAL (10%), DAL (10%), UAL (8%).