The B area controls aircraft in most of Northern Oregon, from approximately 150 miles off the western coastline east, roughly to Idaho, between Portland and Eugene, Oregon. There are four low altitude sectors (Sectors 4, 5, 6 and 34) controlling the surface up to 24,000 ft and three high altitude sectors (42, 46 and 16) working traffic at and above 24,000 ft. Sector 4 works a shelf along the I-5 corridor from Portland, OR to Olympia WA, below 9000 feet. Sector 6 controls a wide array of traffic departing from Portland as well as all commercial traffic arriving Portland from the south. Both sectors provide approach control services to many small airports. Sector 6 is the busiest low altitude sector in the B area. Sector 5 works Portland departures to the southeast and supplies approach control services to the Bend-Redmond-Sun River recreational hub. Sector 34 works traffic arriving and departing Portland to the east.  The B area high altitude sectors are split along north/south lines. Of the high altitude sectors, Sector 42 is the furthest west and controls traffic from Seattle and Portland to San Francisco Bay area destinations, as well as sequencing the Portland arrivals from California into one stream. Sector 46 is the middle sector. It controls the Portland departures to the southeast and sequences all Seattle area arrivals from most California and Nevada airports into one stream. Sector 16 controls the airspace over Eastern Oregon and provides service to multiple streams of aircraft including Portland departures and arrivals to the east, Seattle area departures heading to south east and traffic transiting from the Spokane area to all California destinations.  Sector 16 is the busiest high altitude sector in the B area.  There are two approach control facilities within the B-area. Portland Approach controls an area within 30 miles of the Portland Airport below 13,000 feet;  Cascade Approach controls a similar area at Eugene below 9000 feet. The B area takes responsibility for Cascade Approach’s airspace at Eugene during the nighttime hours. The Cascade Mountain Range is dotted with prominent peaks that present a terrain risk to small aircraft.