Basic Airport Traffic Pattern
We’ll start with an idealized situation. Let’s assume we’re flying a pattern at a non-towered airport with no one else around, with a 1000′ AGL pattern altitude and no other complications. This is the staring point from which we’ll make later adjustments. The speeds and flap settings I give are appropriate to most Cessna 172s (the 172N/180hp has a final speed of 62kias). I follow the rule that bank angle should never exceed 30 degrees in the pattern.
Remember that we maintain airspeed in the pattern by adjustments to pitch and that pitch is most easily seen by the relative position of the cowling to the horizon. Any change to power or flaps should be followed by an adjustment to trim. Trim allows you to concentrate more on looking outside and control than on basic airspeed maintenance.
Shape and Size
We want a rectangular pattern, with our downwind about 0.5-1.0 nm from the runway (0.75 seems to work well with the power settings I suggest). Initially, you may want a slightly wider pattern to give yourself just a little extra time, but please don’t fly a 747-sized pattern. Keeping this standard pattern, we’ll fly about 2 nm from the point where we begin our descent and will need to lose 1000 ft in about 2 minutes of descending.
Takeoff and Upwind
On takeoff, we want to stay over the runway centerline and on our upwind leg we want to fly on the extended centerline of the runway. Since your nose will be high, you may not be able to see the ground ahead of you, so choose something on the ground to parallel or a point on the horizon to fly toward. We usually choose a airspeed near Vy for our climbout.
Look before you turn – for aircraft entering the pattern or ahead of you in the pattern. Crosswind should be perpendicular to the runway, continuing to climb at our chosen airspeed (pitch angle) and occasionally looking at altitude to determine when to begin our level off at traffic pattern altitude (TPA).
For most airplanes and situations we reach pattern altitude as we are on downwind. Remember to reduce power a little before reaching pattern altitude (~1900 rpm) and to keep airspeed under control. By the time you are downwind and along the runway, you should be configured for 70 kts with 10 degrees of flaps at pattern altitude, flying parallel to the runway. Compare the window frame to the runway as a starting reference, but remember crosswinds may require you to adjust from that. Note the position of the strut relative to the runway for an estimate of distance from the runway. Maintain a pitch angle that gives the desired 70 kts airspeed and trim so that the airplane maintains that pitch/airspeed on its own. Check trim by releasing the yoke for a second. Does the nose immediately pitch up or down? If so, then it isn’t trimmed. Pick a point on the horizon to help guide you, especially once you are beyond the end of the runway.
When you have your landing point (usually the runway threshold/numbers) off your wing (a.k.a. abeam), start your descent by ensuring carb heat is on and reducing power. Try 1400 rpm – that usually gives around a 500 fpm descent. As you reduce power, the nose wants to drop and airspeed increases. Anticipate this change and adjust yoke back pressure and trim to maintain your pitch angle and airspeed.
Now we use that point on the horizon to keep us parallel to the runway, while monitoring our position relative to the runway and maintaining our pitch angle and airspeed. When it appears that it is a 45 degree angle back to the landing point, we’re ready to turn base. In an ideal world, we’ve flown about .75 nm since we began our descent.
Turning onto base, add a second notch of flaps (now 20 degrees) and trim for 65 kts. If you apply the flaps, the 5kt slow down should happen almost automatically, but you’ll need to re-trim to keep the appropriate pitch angle, which should be very similar on downwind, base, and final.
Base should be flown perpendicular to the runway. To know when you are, you need either an aim point, a target heading, or you need to have the runway in sight.
While on base, check the picture of the runway. Do you seem high, low, or right on? You should soon be able to tell if the glide angle to the runway looks normal. A small adjustment to power or flaps here is better than a large adjustment on final
Turning to final, configure for 30 degrees of flaps and trim for 60 kts. If you turn too late, and overshoot the extended centerline of the runway, resist the urge to bank more than 30 degrees or to use rudder beyond what is necessary to stay coordinated. A gentle correction back to the centerline, or a go around are preferable. For flying on final, I’ll refer you to the treatise on approach and landing
- Too long a crosswind leg – this is usually where the really wide patterns get started
- Letting airspeed pick up during the upwind to crosswind turn, crosswind to downwind turn, or as you level off. Be sure you are in the white arc before adding flaps. The easiest thing is to never get out of the white arc.
- Leaving too much power on too long and overshooting pattern altitude
- Angling in or out on downwind
- Underbanking – a 20-30 degree bank is safe in the pattern. Constantly flying 5-10 degree bank angles will cause you to fly too large a pattern and increases the amount of time where your view of the runway is blocked by the wing (in a high wing)
- Overbanking to correct late turns
- Letting airspeed rise (nose drop) on turns
- Letting airspeed drop on turns – a tendency to pull too much, as though you are trying to keep a level turn – DON’T DO THIS.
Complications – adjusting your pattern to reality
While our example of a non-towered, non-busy, uncomplicated pattern is a good starting point, it is not the norm in the real world. It serves as a starting point for necessary adjustments outlined below.
Other traffic in the pattern/tower instructions
With other airplanes in the pattern, you often have to alter your pattern for a smooth flow of traffic. This may include extending upwind or downwind, making 360 or 270 degree turns, making s-turns, or adjusting your speeds in the pattern. Safe adaptability becomes the key. Never try something with which you are not comfortable (“unable” is a valid response to a controller who is being a little too creative in his requests).
By far, the most common change is “extend downwind, number 2, cleared to land”. In a towered environment, this means someone is ahead of you to land. Your base turn should not occur at least until
1) you’ve been cleared for landing or told to follow the other plane and
2) you see the airplane you are following and confident of spacing – for airplanes of similar speeds this means at least abeam the other plane as you are on downwind and the other on final
Depending on the length of additional downwind, your descent may have to be delayed until abeam the other airplane, or on base, or even on final. In this situation, your goal is to not get too low, too far from the airport; that’s a bad place to be if an engine quits.
The same procedure applies, if you are number 3 or number 4 for landing and are on the downwind. Make sure you are identifying the right airplane to follow, before turning base (nobody likes being cut off on final).
In a non-towered environment, the situation is the same, but you are responsible to identify where you fit in the flow of landing planes.
The further downwind you get, the harder it can be to determine whether you are angling in or out from the runway. Angle in, and you risk getting in the way of planes on final. Angle too far out and you risk becoming invisible to other airplanes behind you on downwind. This is where a well chosen target point or a gps can really help; always keep the aircraft ahead of you in sight.
Adjusting speed to mix in with traffic
If you fly to a larger airport with more high performance airplanes or jets, a 70 kts pattern may win you no friends or may significantly delay being cleared to land. You need to learn how to adjust to the request for “maximum forward speed to the airport, 737 5 miles in trail”. Practice ahead of time is the best idea here. In the same vein, being told “number 2, follow the Cub on final” may mean time to slow down a bit more (though not below final approach speed) or delay your base turn to give him more room.
Different pattern altitudes
While 1000′ AGL is the most common pattern altitude, 600′ – 1500′ AGL is not uncommon. If you fly the exact same pattern for 600′ AGL that you do for 1000′ AGL, you’ll find the ground earlier than you should. Some adjustment is necessary. You could delay addition of flaps, you could fly with slightly more power, you could delay your descent, you could fly a smaller pattern, or some combination of each. Which solution you choose will depend on the situation.
For higher patterns, the opposite are options – reduced power, earlier/more flaps (or other methods of drag), or a larger pattern; I wouldn’t however suggest starting the descent earlier than abeam the numbers.
Noise abatement procedures/non-rectangular patterns/obstructions
Almost every airport in an urban environment has a noise abatement procedure to help reduce the impact of aircraft noise on neighbors who work or live near the airport. These procedures should always be followed if safe operation allows it. At non-towered airports, there are often signs near the deaparture runways to describe the procedure. At towered airports, don’t hesitate to ask.
The most common noise abatement procedures seem to be a turn on upwind, such as following the wash at El Monte (RW19), following the train track at Fullerton (RW6), over the lake at Brackett (RW26) or over the golf course at Santa Monica (RW21). These turns will force a non-rectangular course, and either shorten or lengthen your crosswind turn. At El Monte RW19, the crosswind almost becomes a direct turn to downwind to avoid flying too wide of a pattern.
Next most common are instructions to turn crosswind before a certain point, after a certain point, or no earlier than a specific altitude. In some cases, this means reaching pattern altitude while on upwind, or turning a crosswind at a lower than normal altitude (if safe).
Finally, there may be obstructions that force the timing of turns in the pattern or delay descents from pattern altitude. A perfect example is the KFI tower just northwest of Fullerton. Descents from pattern altitude north of the runway should only occur once you are confident of the location of the tower and turns from upwind on 24 should only occur when you have the tower in sight and are confident of turning inside or outside of the tower. Some are more obvious, like the need to turn base before the mountain on left pattern to Flabob.
For the most part, a properly flown pattern will work just fine with parallel runways, but I suggest that you make adjustments to avoid possible conflicts. It is exremely important that on final and upwind, you don’t drift into the path of potential traffic on the parallel runway. This may mean a slightly early turn from base to final and a slight angle on your final approach with corrections closer to the runway. It also means being aware of your position relative to the runway is extremely important on upwind, as it can be difficult to see your runway underneath your plane.
When things go wrong – simulated and real
I encourage every pilot to practice engine out approach and landing on a regular basis. It gives you confidence should that ever happen and improves your handling of your plane. This exercise is traditionally done by closing the throttle to idle right as you are abeam the landing point (as is necessary for the commercial rating). I suggest that you experiment with “loss of power” at other points in the pattern – what happens if you lose power earlier on downwind? How about at your turn from downwind to base? Can you always make it to the runway? These tests may drive you to change how you fly your pattern.
But how do you get a feel for the adjustments necessary when you don’t have power? DISCLAIMER: Please never let a simulated engine out become a real emergency; make sure you apply carb heat and use power if you find yourself too low and come back to try it again…
The ability to approach and land, engine out, hinges on your ability to judge your glide and your ability to use the tools available to change the glide. Within bounds, it is better to be high than low; we have ways of losing altitude, but without an engine, no real ways of adding altitude.
Start with the standard setup of carb heat and idle power, when abeam the numbers on downwind (coordinated with tower or other traffic as necessary). Begin a gentle arc with the landing point at the center of the arc. If the glide angle to the landing point seems too shallow, adjust the turn more directly to the runway. If it seems too high continue the turn or adjust very slightly out.
When can I turn cross-wind?
When it is appropriate and safe to do so. This depends on noise abatement procedures (which may restrict altitudes or points at which turns can or must be made), terrain, climb performance of the airplane that day, and other aircraft that you are following in the pattern. In general, you should not turn crosswind prior to the departure end of the runway, unless told or approved to do so by the tower. I’d also suggest 500′ AGL as a typical minimum before turning, unless other criteria or instructions compell you to do so. The AIM indicates that the crosswind turn be made within 300′ of TPA, but than can make for an awfully long upwind leg.
How do I estimate distance from the runway on downwind?
Try putting the airport in the GPS as your destination and noting the lowest distance you see (it will be when you are abeam what is considered the center of the airport)
Compare the known length of the runway to your distance from it.
Ask your instructor to show you.
Look on google earth ahead of time for points on the ground to estimate by.
In many parts of the country, major roads may also have a 1sm spacing
Ask the tower (if they have radar coverage).
What speed should I use for my climb?
We usually choose a airspeed near Vy for our climbout. This gets us away from the ground as quickly as possible; altitude gives us options in an airplane. If we have an obstacle, we may instead initially choose Vx; a speed higher than Vy may be chosen to give better visibility over the cowling or to improve cooling of the engine on warm days.
Do I always need carb heat?
No. But in your primary training, we want to reinforce the habit of putting carb heat on at times of low power operation, like descent for landing. Later on, when you know the conditions and understand the principles, you can decide if carb heat is necessary or not, but it should a specific decision to not use carb heat, rather than the default.
Why do we call the legs something-wind?
We usually take off and land into a headwind if the option exists, so this default is used in the naming. Even if you have to takeoff with a tailwind, you are still on the upwind leg.