Devil in the details.
The other day my favorite CFII and I were reviewing our upcoming practice instrument approaches into Mineral Wells, Texas. He pointed out a detail on the ILS or LOC/DME RWY 31 that completely escaped my attention (and would have been a "gotcha" on a checkride). A superficial glance at the chart leads you to believe that after the IAF at MQP you fly outbound on the localizer, execute a procedure turn south, and then back inbound normally. But taking a closer look you see that you are to fly outbound on the MQP 127 degree radial, then inbound via the same radial until CUTIS, and then track the localizer inbound.
Why not just track the localizer outbound (which is what I would have instinctively done)? What would be wrong with switching to the localizer earlier than CUTIS? CUTIS is identified by the 5.5 DME from the localizer, but in theory you would still be navigating via the VORTAC by the time you get to CUTIS. Why is the approach designed this way? I guess the lesson is: pay attention to detail.
Shady Shores, TX
Somebody probably just goofed. Lee Smith, our resident TERPSter, saw nothing that would have suggested this design. There was an Arndt 1 (Inset on chart) to this procedure that aligns these two values (among other changes), negating the whole question in the first place.
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