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The Traffic Pattern

The Traffic Pattern

Some people may be quite confused when I use the terms downwind, final, or base. These terms come from a common flight path around an airport called the traffic pattern. The FAA's AIM (Aeronautical Information Manual) defines the traffic pattern as "the traffic flow prescribed for aircraft at, taxing on, or taking off from, an airport". The traffic helps pilots in high traffic areas by helping them set up for a good landing. Imagine of there was no traffic pattern; airplanes would be approaching the runway from every direction. Now imagine the confusion this might cause. By using a traffic pattern, operations at an airport become uniform and consequently safe.

Let's start by examining the traffic pattern from the standpoint of an aircraft taking off. For this example, we will be departing runway 21 (the airplane will start by the number 21 and accelerate towards the number 3). The airplane will climb on whats called the upwind leg. Once the airplane has reached a safe altitude (I use 500 feet as a general rule of thumb), the pilot has a decision to make. He/she can either choose to leave the pattern (perhaps to visit another airport) or remain in the traffic pattern (if he/she wants to stay at the airport maybe to practice landings). If he/she wishes to leave the pattern, the pilot can either continue straight forward, or turn 45 degrees left or right. If you decide to head back to the runway, a left 90 degree turn is made onto the crosswind leg once reaching a safe altitude. While continuing on the crosswind leg, the airplane is continuing to climb to traffic pattern altitude. The traffic pattern altitude varies between each individual airport. Judging when to turn onto the downwind leg is a tad difficult at first. The general rule while in the traffic pattern is to always remain within gliding distance of the runway. The star situated along the downwind leg is called the downwind key. This is an imaginary point situated directly across from the runway numbers. At this point, the pilot performs operations to prepare the plane for landing such as lowering the landing gear and slowing the engine. Just like from crosswind to downwind, the turn from the downwind leg to the base leg is up to the pilot. The same situation goes for the turn from base to final. While flying on the base and final segments of the traffic pattern, the pilot begins to descend. Once on the final leg, the pilot aims the nose towards the runway numbers and lands the plane. Thanks to the traffic pattern, another pilot and aircraft have landed safely. When entering the traffic pattern, the airplane enters at a 45 degree angle to the downwind leg as shown by the diagram. When entering the pattern the plane will already be at the specified pattern altitude. Once situated parallel on to the runway on the downwind leg, the pilot continues the same procedures aforementioned.

This, of course, is just one example of a traffic pattern. Depending on the airport and it's surrondings, the pattern can be modifyed for specific situations. Information about the traffic pattern can be found in it's A/FD (Airport/Facility Directory). Thanks for reading!!!

-Evan Krueger

16 Responses to “The Traffic Pattern”

  1. Thank you. This information was very uesful.

  2. I am Canadian and was told by an American that many pilots approach the traffic pattern by crossing over the field at circuit heightfrom the upside then joining the mid downwind. I noticed that your article did not show this approach. Would you please clarify this issue for me.
    Thank so much

    Jocelyn

  3. Yes, Jocelyn, this is common for pilots approaching a non-towered airport from the opposite side of the runway from downwind leg. As always, the pilot should announce her intentions on the CTAF a mile or two from the airfield. It would sound something like, "Aeronca 967, two miles east, will be making a mid-field fly-over and join the downwind for 2-1."

    This is done to avoid the time/fuel penalty of circling at a distance from the airport to be in position to make the 45 degree downwind entry.

    Is this not done, ever, at non-towered airports in Canada?

    - Sam

  4. Jocelyn. I have also hear of certain pilots performing this maneuver. Skimming through the regulations , I did not find any reference to this practice. From what I understand, certain pilots will do that to make sure that the landing area is safe to land on. This is common in bush flying. Hope this helps. Thanks!!!

    -Evan Krueger

  5. Jocelyn, I believe the approach you are referring to is a midfield crossing (usually 500 feet above the traffic pattern, for obvious reasons) and decent onto the 45. This is usually used to enter the pattern from the opposite side, such as a pattern on the west side of the airport, while you are approaching from the east. Unless you're talking about something completely different, as I've never heard of someone crossing at pattern altitude. Good explanation though of the traffic pattern.

  6. Al Van Lengen Says:
    February 15th, 2009 at 11:14 am

    This is a great subject and one of my pet peaves on teaching at a non-towered airport. Evan does a great job about pointing out the hazards and complications at non-towered airports. I would like to correct a common error though, the upwind in your diagrahm is actually your departure leg, an upwind leg is one that is flown parallel to the unway in the same direction as traffic but on the reverse side of the downwind. See figure 4-3-1 in the AIM -the AIM identifies the legs of the pattern as follows:

    1. Upwind leg. A flight path parallel to the landing runway in the direction of landing.

    2. Crosswind leg. A flight path at right angles to the landing runway off its takeoff end.

    3. Downwind leg. A flight path parallel to the landing runway in the opposite direction of landing.

    4. Base leg. A flight path at right angles to the landing runway off its approach end and extending from the downwind leg to the intersection of the extended runway centerline.

    5. Final approach. A flight path in the direction of landing along the extended runway centerline from the base leg to the runway.

    6. Departure leg. The flight path which begins after takeoff and continues straight ahead along the extended runway centerline. The departure climb continues until reaching a point at least 1/2 mile beyond the departure end of the runway and within 300 feet of the traffic pattern altitude.

    When entering a traffic pattern at a non-towered airport a pilot should use extreme caution and use the "recommended" procedures in the AIM. A pilot should realize that there may be traffic in the area without radio's, traffic that may not be using standard patterns, aircraft transitioning the area at low altitudes and many other hazards. This is an area where the pilot should be constantly scanning for traffic and not have their head down in the cockpit.

    Crossing over the top of the runway at least 500' above Traffic Pattern Altitude allows the pilot to observe the area and determine if there is any other traffic. My recommendation is to continue out from the runway 3 - 5 miles before decending to Traffic Pattern Altitude and returning in on the 45 to enter your downwind. This will assist in maintaining clearence from aircraft approaching onthe 45 at traffic pattern altitude. This again is recommended by the AIM. Doing this will cost you and extra 5 - 10 minutes of fuel but may also save your life.

    Communication at a non-towered airport is key for those that have radios. The CTAF or UNICOM can get congested on beautiful Saturday morning with everyone giving their life histories for the past week. Communication should be kept short and descriptive, giving airport, your abbreviated call sign, location in the pattern and airport again, i.e.
    Dresdon Traffic, Skyhawk 39Y, 3 mile 45 for left downwind 28, Dresdon Traffic.

    I would also suggest besides the AIM chapter 4, is to review Advisory Circular 90-66A, and AOPA's safety bulletin on operations at Non-Towered Airports.

  7. Someone beat me to it. Good call, Al! .. Yep the upwind is mislabled, that leg on takeoff is the DEPARTURE leg (check the AIM for clarification). Despite the latter you will often hear in pilot parlance pilots erroneously referring to departure leg as UPWIND (which is wrong).

  8. This has been, since student days through my now low hour PPL my most worrisome part of flying. Between not identifying the runways until practically over them, and/or trying to orient my heading indicator to the paper diagrams of the runways, which are written OPPOSITE the heading indicator as well as moving at 100mph and trying to decipher where other planes and helos are in the pattern, I become quite nervous.
    I am taught: midfield crossover then descent WHILE turning "teardrop" for the 45. Turning WHILE creates a better visual target for others. I do not like the semi-blind turn. OTOH, I do not like descending while flying OUTbound before the turn as it leaves me blind to my rear while planes might be climbing out of the pattern. OTOH, I do not like descending AFTER the turn while back INbound as it is descending quite close to the pattern and I might descend onto someone already at pattern altitude. (BTW, I am taught to be at pattern altitude 5 miles out which is why I think of this factor). All present pros/cons so I continue to do it the way I was taught, turning while descending expect I do it further out. Also, I do not like the 500ft above TPA as that's normal turbine/twin TPA so one instructor said do it 1000ft. Talk about steep descents very close to the pattern! I make the turns wide and shallow and often level the bank to look. It's a pain and I sweat it quite honestly, not a way to get me to enjoy flying. That said, now that I fly with my instructor as a pilot rather than student, he enters on the crosswind, (quite cautiously of course) and in fact so has everyone else I've flown with. Talk about confusion, distraction and lack of confidence!
    Any opinions would be hightly appreciated, and may save lives.

  9. Al and Cecil, both wrong...Upwind has and always will be in line with the runway after takeoff prior to turning crosswind. Upwind becomes departure leg once outside normal traffic pattern operations (Hence --> DEPARTURE leg). A lot of pilots planning to stay in the pattern call up on departure leg (you're not departing....?)

    Keep it real. Sometimes the FAR/AIM is misleading, use common sense.

  10. Al and Cecil, both right. Bill, misinformed and unhelpful. The FAR/AIM contains the definitions of terms used by pilots operating in US airspace. You cannot argue that the definition of a term is different from the one provided by the very authority responsible for deciding the definition.

    The "upwind leg" is clearly defined, and the definition is not arguable or "misleading". It is what it is. The fact that some pilots through poor training, suceptibility to hangar-talk "instruction", adherence to outdated information, or willful ignorance choose to misuse terms clearly defined in the FAR/AIM does not invalidate the definitions. It merely points out the need for better education. Allow me to do my part:

    http://www.faa.gov/air_traffic/publications/atpubs/AIM/Chap4/aim0403.html

    Two questions: if the leg parallel and opposite to the downwind leg is not the "upwind" leg, just what is it? And when the tower instructs me to "fly left upwind for runway one-eight; I will call your crosswind", what should I do? Fly right down the middle of the runway? Or perhaps remind the controller that FAR/AIM definitions are misleading and that he should keep it real?

    On the topic of pattern entry from the upwind side, I was taught to fly over the top no less than 500' above the *highest* published pattern altitude (takes care of piston/turbine differences), continue past the airport for a couple of miles while descending to pattern altitude, then turn back for a normal 45-degree entry. I continue to use that technique because I believe it to be safe and I fly wet-rate rentals so the extra fuel isn't a concern (I understand that it *is* a concern for owner-pilots). IMO, the benefits of this technique are:

    - More time to observe the airport area from above pattern altitude
    - Good opportunity to see aircraft incoming from the downwind side, both during the initial outbound leg of the teardrop and during the right-hand turn (in a high-wing aircraft)
    - Good opportunity to observe the pattern during the normal 45-degre entry
    - Easy to adjust pattern entry point to allow for spacing with other traffic (S-turns, circles, etc.)
    - Every entry into every pattern is (eventually) the same for me: 45-degree right-turn (for left-hand patterns) onto the downwind leg

    The main benefits I've seen for the direct entry onto downwind from a mid-field crosswind are:

    - Less fuel used
    - Left turn (for left-hand pattern) allows pattern to be visible for high-wing aircraft

    My main concern with this technique is that once I'm "inside" the pattern at pattern altitude, my options for adjusting my pattern entry become limited. If a NORDO aircraft shows up that messes up spacing, where do I turn? Steep turn right over mid-field? The upwind leg right behind me is a valid pattern-altitude leg for other planes so that may box me in as well.

    Contrast with the "normal" 45-degree entry from outside the pattern. If something pops up that requries a pattern-entry go-around, I've got miles of airspace (probably) behind me that I can turn to for circling or other avoidance.

    I've had flight reviews where the instructor questioned the technique, so apparently it's not universally taught. I'm not a big fan of "to each his own" in flying, since being able to predict what other pilots will do greatly enhances safety, but with upwind-side pattern entry I guess to each his own will have to suffice.

  11. The AIM is not regulatory, FARs are. Unless of course, the AIM references referring to preexisting FARs. (Upwind not defined in FAR 1.1)

    http://www.faa.gov/air_traffic/publications/ATpubs/AIM/Preface/aim-far_ac.html

    Nothing about common sense that is wrong.

    1. When have you been instructed to fly 'a left upwind' .. I never have, ever. Nor have I ever been instructed to make a reverse pattern entry.

    2. Mess up spacing, see traffic earlier/slow down, should never have to do a 360 if you are paying enough attention as PIC.

    I think I would teach my student how to do 'the overhead' rather than fly 'a flight path parallel to the landing wunway in the direction of landing.'

  12. I teach my students to fly either a 45 degree entry or an overhead entry if they need to look at the windsock. I also teach my students to establish communication 10 mile out, that's only 5 minutes in a GA plane, in order to determine entry and traffic density.

    Entering the pattern by descending into an extended downwind or extended straight-in, midfield overhead entry at pattern altitude or upwind entry over or crossing the runway centerline at pattern altitude are all dangerous, because they limit your ability/opportunity to spot and merge with traffic already in the pattern.

    If there is traffic in the pattern, and you have monitored radio calls, there is no need to look at the windsock so a 45 degree entry is best. More traffic requires a longer 45 degree entry. The AIM doesn't specify how long the 45 degree entry leg should be, and the length should be adjusted as needed to spot and merge with traffic already in the pattern.

    If my student have to overfly the field in order to get to the 45 degree entry or look at the windsock, I require them to fly 500' above traffic pattern altitude until clear of possible downwind traffic. This really only adds 2-3 minutes compared to turning and descending directly into down wind.

    I also teach them that even if they don't hear any calls, they still need to assume that someone may be in the pattern.

    The reccomendation to stay within gliding distance of the runway in the pattern is a good one, but not without exceptions.

    I instruct in DA-20s and PA-28s. The DA-20 can glide 2 miles to the runway from 1000' tpa, which is a rediculously distant downwind. On the other hand the PA-28R Arrow can barely make 1/2 mile from 1000'tpa. Bonanzas and many other private aircraft glide even worse. Lufthansa shares many of the non-towered fields I use for training and they fly a 2000' pattern in order to practice power-off landings from normal downwind distances.

    As far as the AIM being non-regulatory you are correct, but if an accident or incident results from your failure to follow AIM reccomendations, the FAA will cite you with reckless and neglegent operation. So no the AIM isn't in fact regulatory, but in practical operation it really is.

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  15. hi,I want to know is there any illegal way to separate traffic in traffic pattern(e.x in downwind)and departing traffic? I can't find any solution and subject about this type of spacing in icao documents.I'll become grateful if you could help me.

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