Tuesday, August 9, 2011
Making Sense Of The Back-Course Approach
They’re the words every instrument pilot dreads: “Cleared for the back-course approach”
Still, they're a nuisance we're sometimes forced to deal with. It's so simple and logical to fly into the needle that pilots are nonplussed at the thought of flying the needle "backward." In every other variety of instrument procedure, the pilot corrects into a diverging needle—needle left, correct left, needle right, correct right. Even on an NDB approach (assuming the station is still in front of the aircraft), the pilot flies the head of the needle, and corrects left for left, and vice versa.
Pound that message into a pilot's head a few thousand times during private, commercial and instrument training, then see what happens when sensing becomes reversed.
Back-course (BC) localizer approaches subject a pilot to reverse needle indications on the OBS. You fly right to correct left and versa vicea, counterintuitive to pilots who have been taught that you always fly into the needle.
Fortunately for those pilots who use the airspace regularly for business and pleasure, BC approaches are rare, and that's understandable. Whenever possible (barring complaints from the neighbors under the proposed approach path), airports lay out their runways into the wind. Geographic and political features sometimes make that impractical, but most of the time, runways are oriented to allow pilots to benefit from some slight headwind on landing.
Similarly, the prevailing ILS is typically oriented to the longest runway. The implications for instrument students should be obvious. It's almost impossible to practice back-course approaches, because you're most often flying directly into the flow of traffic coming off the most active runway.
For better or worse, I had a back-course approach in my backyard when I was working on my instrument rating in the '70s. I learned to fly in the Los Angeles Basin, good news and bad news, depending upon your point of view. Then, as now, LA was one of the world's busiest areas for air traffic, especially general aviation. At one time in those questionably halcyon days, the Los Angeles Basin owned four of the 10 busiest airports in America: LAX, Van Nuys, Long Beach and Torrance. The last three were predominately reserved for light aircraft, though Long Beach did have some airline operation. Collectively, there were something like 18 airports crammed into a fairly small area. In short, Los Angeles airspace was (and still is) very busy.
The good news was that you could find practically any kind of approach you could imagine, and the Orange County back course was one of them. My instructor made it a point to insist one morning that we be in position to shoot the runway 1 back course to Santa Ana, Calif., at sunrise, the very moment the airport opened for business and a half hour before the parade of airline 737s began departing and arriving. Fortunately, there were no other idiots up that early, so we were able to get in two practice back-course efforts to missed approaches before the tower shooed away our little Skyhawk.
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