An eye-grabbing feature of the L-1 low altitude en route chart that covers a swath of West Coast airspace from Eugene, Oregon, up to Vancouver, British Columbia, is this: From Seattle, Washington, north to Everett, Arlington, and beyond, no airway straddles the high terrain east of V-23.
Elevations to more than 11,000 feet in the Cascade Range account for that. Fortunately, the flight planning exercise your instructor has constructed for today covers a flight westbound over lower terrain from Arlington Municipal Airport to William R. Fairchild International Airport in Port Angeles.
Routing is still not obvious, since no nearly straight path is published. Perhaps after flying the Arlington One Departure—a radar-required standard instrument departure that you have been requested to look over—radar vectors will provide a low-workload transition on course.
The SID chart’s graphic, by contrast with the en route chart’s crisscrossing airways and superimposing slices of special-use airspace, is simplicity itself. Whether you depart on Runway 16 or Runway 34, maintain runway heading to the published altitude, then turn to 250 degrees and climb to 2,000 feet, and "expect radar vectors to assigned route, expect clearance to filed altitude 5 minutes after departure."
Your CFII usually follows up route-planning drilling with a review of appropriate regulations, and today’s selection is 14 CFR 91.185, "IFR Operations: Two-way radio communications failure." What if it occurs before you receive the expected radar vector, in IMC?
You'd squawk 7600, of course. Now, as you data-mine the regulation’s requirements for this scenario, it's clear why the only navaid on the SID is the Paine VOR/DME, and why the frequency and approximate course to it demand your attention, even though it is off your intended course.
The SID’s lost communications procedure states, "If no transmissions are received for 3 minutes after departure, climb to filed altitude direct PAE VOR/DME, thence via assigned route."
That crucial provision demonstrates the importance of SIDs to pilots who rarely have a chance to use them, or who avoid using them by noting "No SID" on IFR flight plans. As the Aeronautical Information Manual explains, all departure procedures "provide the pilot with a way to depart the airport and transition to the en route structure safely. Pilots operating under 14 CFR Part 91 are strongly encouraged to file and fly a DP at night, during marginal Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC), when one is available."