Page 22 - January 15 Volume 19 Number 1

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In a Lear 40, it‘s a very short 28 minute, 177 nm-mile trip from Skagit Regional (BVS), just north of Seattle, to Hillsboro Airport (HIO), west of Portland. As we pass over the volcano-flattened mountaintop of Saint Helens and start our descent, Jeff H (the pilot flying) and I find ourselves wishing we could delay arrival by another hour or so.
Although VFR conditions were predicted for our arrival when we planned the flight, we are now just six minutes from the Initial Approach Point (IAP) and HIO is reporting fog, ceiling variable 100–200 feet and visibility varying between 1⁄4 and 1⁄2 mile. But, the weather otherwise is pretty decent, with tops at 1,500 feet and calm winds. In addition, HIO has a good (200 and 1⁄2) ILS approach to runway 13, with the surrounding terrain relatively flat. The missed approach procedure is also quite simple, a climbing right turn back to the VOR for a hold, where we could reconsider our options. Unfortunately, no other aircraft have tried the approach this morning, so we are going to be the brave guinea pigs.
After a long respite of fairly good weather, this is my second approach to minimums in two days, including one yesterday into Juneau, Alaska with a Lear 35. The experience makes me again appreciate the effect local topography can have on flying weather, sometimes good, sometimes bad. A basic understanding of how this can affect the region you are operating
20 • TWIN & TURBINE
in, plus knowledge of the services available at nearby airports, can make the approach procedure itself much more relaxed, and the missed approach options much easier to decide upon. It can also influence the passengers’ experience, either frightful or comfortable and reassuring.
HIO is located in a valley on the western side of the Cascade Mountains, at the confluence of the Columbia and Willamette rivers. In the fall, as surface temperatures drop, the temperature/dew point spread closes, and fog can blanket the entire area for days at a time. A key to understanding what the HIO missed-approach options might be is that the fog-producing conditions rarely move eastward up
the Columbia River gorge more than 30–40 miles. The reason for this is the pressure is usually higher on the eastern side of the Cascades, the mountains themselves act as a barrier, and the gorge itself is so narrow that moisture-bearing weather has trouble squeezing through. For all these reasons, The Dalles (DLS), just 75 nm east of HIO, almost always has sunny and bright conditions when the entire Portland area is fogged in.
In addition to topography, another item to consider during a low- minimums approach is what the passengers are going to think about the experience, and your abilities as a pilot, after it is all over. For most passengers, a missed approach is a just plain frightful event. At one
JANUARY 2015