06/08 – Traffic Patterns and Good Landings

06/08 – Traffic Patterns and Good Landings

By Steve Krog

In past issues we’ve discussed and practiced the maneuvers for understanding the airplane and the effects of wind. Now it’s time to move to the next phase of flight training.

Knowing, understanding, and flying the traffic pattern is critical to making good landings and for flight safety. You’ll never fail a check ride with an examiner if you decide to make a “go around” rather than attempting to salvage a good landing from a poor approach!

All previous flight training was leading to the day when we begin flying the traffic pattern and acquiring, through practice, the skill to safely make takeoffs and landings in your aircraft. Before working on the takeoff and landing techniques though, it is vitally important that we thoroughly understand and properly fly the airport traffic pattern. Many bad landings can be traced directly to incorrectly flying the pattern.

Flying a traffic pattern is a little like driving a car on a road with three lanes of traffic in each direction. A safe driver would never attempt a left turn from the middle or right hand lane of traffic. Rather, the driver would first move safely to the left lane and then execute a left turn - but only after making sure there is no oncoming traffic that would compromise a safe maneuver.

The Traffic Pattern

The airport traffic pattern consists of five segments, or legs: the upwind leg; crosswind leg; downwind leg; base leg; and final leg. Looking at the illustration below, we can easily see where each leg fits into the traffic pattern.

The upwind leg is that portion of the pattern from the time the aircraft leaves the ground to the point where we execute an approximate 90-degree turn to the left. At most airports the upwind leg is flown until reaching an altitude of about 500 feet above the ground (AGL). This is also the most critical leg of the traffic pattern as it limits our options should we have some type of power emergency, but more on that in a future newsletter.

The upwind leg is flown at full power and in a climb attitude. Thus, our forward visibility is somewhat restricted by the nose of the aircraft. At 500 feet we’ll gently lower the nose of the aircraft for a few seconds so that we can clearly see the area in front of us, checking for any oncoming aircraft that may be entering the traffic pattern. Once we’ve made sure we have no conflicting aircraft, we’ll raise the nose and begin a shallow climbing turn to the left, rolling out of the turn when we’re approximately perpendicular, or 90 degrees to the runway from which we departed. We’ve now established ourselves on the crosswind leg. We’ll continue our climb throughout the crosswind leg until either reaching the point for our downwind turn or when we reach 1,000 feet AGL - whichever occurs first.

The crosswind leg allows us to secure proper horizontal separation from the runway as well as giving the aircraft time to continue the climb to the pattern altitude of 1,000 feet AGL. Depending on the wind direction, we may also need to add a small wind correction or crab angle to our crosswind leg. Remember practicing the ground reference maneuvers, especially the rectangular course? (See April and May issues) Here’s where that practice begins to pay off! Note in the traffic pattern illustration the wind direction is from left to right. To prevent the wind from drifting or pushing the aircraft back toward the runway, a small crab angle to the left has been applied. When the aircraft is approximately one-half mile from the runway, we can begin our turn from crosswind to downwind, continuing our climb if necessary to reach 1,000 feet AGL.

The turn from crosswind to downwind is another shallow bank turn of approximately 90 degrees, again depending on how the wind affects our track over the ground. Before beginning the turn though, scan the area in the direction of the turn, checking for any other aircraft traffic. Remember our “S” turns across a road and our turns around a point? In this example we are turning from a crosswind to a tailwind. Thus, our turn begins with a shallow bank and we increase the angle of bank slightly during the last half of the turn.

The downwind leg should be flown parallel to the runway on which we will land, but in the direction opposite of our intended landing. In the traffic pattern example shown, we are flying downwind with a direct tailwind so we need not apply any crab angle. Level the aircraft at 1,000 feet AGL and reduce the power to the recommended cruise power setting. Look to your left and see where the runway intersects the wing of your aircraft. Make a good mental note of this, as it will be vital for repeatedly flying the traffic pattern correctly. Be conscientious about maintaining a constant altitude, as this too will become very important at the end of the traffic pattern. Scan the area for any other traffic.

At the approximate midpoint of the downwind leg, apply carburetor heat and leave it on for the duration of the traffic pattern and landing. When our left wingtip is opposite of the end of the runway on which we will land, reduce power to the power setting used when practicing slow flight. (In a Piper J3 Cub, for example, cruise power is about 2,300 RPM. Reduce power to approximately 1,700 RPM.) Continue flying the downwind leg, but while doing so, position the nose of the airplane in the descent attitude previously established during our air work.

When reaching a point that is about a 45-degree angle from the end of the runway, begin a descending left turn using a shallow to medium bank angle. Roll out of the turn after completing a 90-degree turn. Continue holding the nose in the descent attitude position. If we have wind, establish a crab angle to prevent the wind from moving us away from the runway.

The ground track of the base leg should be perpendicular to the runway. Once established on the base leg several things need to be accomplished. First, scan the area to the right off the approach end of the runway; there may be other traffic landing that we previously didn’t see, or the other landing traffic may not have followed correct procedures and is making what is called a straight in approach. After scanning and clearing the area for other landing traffic, we want to check our altitude. Are we a little too high? A little too low? At this point we can adjust by either adding or further reducing power. If it looks and “feels” about right, go with your gut instinct.

Now it is time to plan for your turn from base leg to the final leg, or final approach. We do not want to overshoot or undershoot the runway, but rather complete the turn so that our aircraft is aligned with the centerline of the runway. Begin your turn using a shallow bank angle and increase or decrease the bank angle as necessary to be able to roll out of the turn lined up with the center of the runway. If you’re already at a medium bank angle and you see that you’re overshooting the runway, it is better to execute a “go around” rather than increasing the bank angle to a steep bank. (That’s only asking for trouble!) We also want to thoroughly check the end of the runway to ensure there are no other airplanes or other possible obstructions, such as the man mowing the grass near the runway, which could compromise a safe approach and landing.

Once the turn from base to final is completed and our airplane is again in a wings level descent attitude, continue maintaining the desired descent angle speed and reduce any remaining power to idle. We’re now established on the final leg, or final approach, in preparation for the landing. Continue your descent until you are approximately 20 feet above the runway.

At this point, apply enough backpressure on the yoke or stick to stop the descent. In many of the training aircraft, it is not possible to see the runway over the raised nose. So, we must now make a line of sight adjustment and look slightly off to the left or right of the center of the airplane to maintain good forward visual contact with the runway. The aircraft will continue slowing and begin to settle or sink. Remember, the wing is no longer generating enough lift to maintain altitude. To compensate, we will apply a bit more backpressure, increasing our angle of attack and generating a little more lift. This is called the flare, or round out, and will slow our descent…but will also cause the airplane to slow even more. Until the main wheels of the aircraft contact the runway, we’ll continue applying slightly more backpressure until the landing touch down is made. Ideally, we want the main gear to touch down at the airplane’s stall speed.

Maintain directional control of the airplane by applying pressure to either rudder pedal as needed until the airplane slows to the normal taxi speed. Then, turn off the runway at the next taxiway and taxi back to the end of the runway in preparation for another take off, flight around the traffic pattern, and landing.

Until you have flown the traffic pattern 8-10 times it will feel as if you are so busy you can’t possibly perform all of the tasks required to fly the pattern and land. But don’t get frustrated; it’s just a matter of repetition and soon it will feel quite natural and comfortable to you.

Possible Mistakes

1. Not taking wind into consideration when making the turn from upwind to crosswind and allowing the aircraft to drift back toward the runway. This will cause you to fly a smaller pattern and not allow time to reach pattern altitude.

2. Not turning from crosswind to downwind at the proper interval. If the downwind leg is too close to the runway, you won’t have time to make your turn to base leg and dissipate altitude before reaching the end of the runway. If the downwind leg is too far away from the runway, the altitude loss while on base will be greater, requiring you to add a lot of power to regain the desired altitude.

3. Not maintaining a constant pattern altitude of 1,000 feet AGL while on the downwind leg. Allowing the airplane to continue climbing will cause you to be far too high when on final approach.

4. Not compensating for wind and drifting out away from the runway while on base leg. Power will again need to be added to regain the desired altitude and position on final approach.

5. Not keeping the aircraft aligned with the runway centerline on final approach. If the aircraft drifts to one side or the other, runway lights make big dents in wings and tail surfaces!

Next Issue

In the July 2008 issue, we’ll discuss takeoffs and landings.