A simple route to final: we bash blindly engaging vectors-to-final and promote loading full approaches, but too much information can be a bad thing.
you're on a vector approaching from the south on the RNAV (GPS) Rwy 26R approach to El Paso International (KELP). The trusty moving map in your IFR-certified GPS shows you'll intercept the intermediate segment between BUSEY and HODAK, the FAF. ATC crackles in your headset a clearance for the approach just as you cross the 268 course from BUSEY to HODAK, so you engage approach mode and track inbound.
Not 30 seconds later, the voice of Approach control pops back on the scene and asks you where you think you're going. He says you don't have a clearance direct to HODAK and you're still two miles shy of the final approach course.
You were just following the procedure you were cleared to fly, right? Well, no. The controller had you on a vector to the final approach course--of 257 from HODAK to the runway. In the ATC world, vectors to final mean directing the aircraft to intercept an extended final approach course outside the gate, which is depicted on the radar scope.
Per the ATC bible 7110.65, an approach gate is "an imaginary point used within ATC as a basis for vectoring aircraft to the final approach course. The gate will be established along the final approach course one mile from the final approach fix on the side away from the airport and will be no closer than five miles from the landing threshold."
The AIM 1-1-19 (o) (6) reflects this with guidance saying, "When receiving vectors to final, most receiver operating manuals suggest placing the receiver in the non-sequencing mode on the FAWP and manually setting the course. This provides an extended final approach course in cases where the aircraft is vectored onto the final approach course out side of any existing segment which is aligned with the runway."
Had the controller wanted you to fly the dogleg from BUSEY to HODAK as published, the clearance would have been specifically a vector to join a segment of the approach.
Activating the vectors-to-final mode on the panel-mount GPS would have removed the dogleg and displayed the correct inbound course. So would any of the techniques of engaging OBS mode and dialing in a 257 bearing to the FAF or engaging Direct To with a manual course of 257. The latter is the best method on many Garmin units as described in "Waypoints Go AWOL," December 2005 IFR.
On most approaches, this is a non-issue, but the winds of TERPS occasionally blow an oddball design our way. No cardinal sin if you turned inbound a bit early, just a tongue-lashing from ATC. But next time it won't catch you off-guard.
Jeff Van West is Editor of IFR.
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|Title Annotation:||APPROACH CLINIC|
|Author:||Van West, Jeff|
|Date:||Apr 1, 2006|
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