September 2008Commentary

Insights

Ground track


Fine tune your wind awareness

Everyone has pet peeves; one of mine is traffic patterns. They should be rectangular with legs either parallel or perpendicular to the runway. Do pilots flying asymmetric patterns think that ground reference training does not apply to traffic patterns? Or are they so intent on landing that ground track is ignored? Or have they not received proper training? That would be inexcusable.

Proper training requires wind. Students do not benefit if wind is absent. On a few occasions, I've scheduled a short cross-country flight to a windy area for ground reference training. An early introduction to sectional charts and dead reckoning and pilotage navigation is an enjoyable diversion--I demonstrate the planning requirements for the flight.

Ground reference training begins with tracking over a road and tracking parallel to a road (see "Square Dancing, May 2008 AOPA Flight Training). Many instructors will tell you to keep the road in the same position relative to the wing or the wing strut. Yes, that will keep you parallel. However, to be successful with more advanced maneuvers, make your primary reference the line that defines your desired ground track. To do this you must visualize that line using specific ground reference points and make certain that the airplane stays on it by turning into the wind.

The next challenge is rectangular patterns. You now combine straight segments with turns, and because you must fly parallel to each side of the rectangle, you must pick out reference points that define the desired ground track.

S-turns across a road are next. No straight lines here. You are constantly turning, and you learn to control a curved ground track by varying your bank angle as groundspeed changes. This maneuver is easy to fly if you concentrate on crossing the road with the fuselage perpendicular to it just as you roll the airplane through a wings-level attitude during the turn reversal, right to left or left to right.

Now you're ready for the airport traffic pattern. That means concentrated takeoff and landing practice, but don't get too excited. The first priority is to master the traffic pattern itself. Warning: If your instructor says, "We can skip basic ground reference maneuvers because I can teach you that stuff in the traffic pattern," change instructors. It does not work, because there are too many other factors that you must deal with.

To start, take off and climb to within 300 feet of pattern altitude on the upwind (departure) leg and turn onto the crosswind leg (Aeronautical Information Manual, paragraph 4-3-4). However, before you turn, clear the airspace in the direction of turn and look where the wing is pointing. It's pointing to where your crosswind-leg ground track should be on the Earth's surface. If you turn toward those references, the crosswind leg will be perpendicular to the runway. Use the same procedure for turning onto the downwind, base, and final legs.

Caution: Before you clear the airspace in the direction of turn, always clear the airspace on the other side and in front of the airplane. Never assume that all pilots will follow correct procedures or that air traffic controllers will advise you of a traffic conflict. Skepticism is a mandatory flight safety requirement.

Obviously, you must apply a wind correction angle in order to remain over your desired ground track. For that to occur automatically, you turn into the wind so that the airplane overflies the ground track's reference points. Remember, the surface wind and wind at pattern altitude seldom are identical.

When you use the wing to point out ground-based reference points prior to turning, consider your wind correction angle. To pick out your next ground track, look to where the wing would point if the wind correction angle did not exist. Your desired ground track will lie slightly ahead of or slightly behind the wing.

Do not use the heading indicator when flying ground reference maneuvers. Use visual references on the ground and scan for traffic. Periodically, glance inside the cockpit to check airspeed and altitude.

Wind and ground track are the nemesis of every poorly trained pilot. Make wind awareness and ground track visualization a top priority--and remember, wind awareness starts when you walk out to the airplane.

Ralph Butcher, a retired United Airlines captain, is the chief flight instructor at a California flight school. He has been flying since 1959 and has 25,000 hours in fixed- and rotary-wing aircraft. Visit his Web site.


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