Understanding an airport’s traffic pattern is fundamental to aircraft pilots and remote pilots (drone operators) alike. As more and more authorizations for drones to operate near airports are issued, remote pilots are encouraged to monitor the radio traffic with a handheld radio and understand what it means when aircraft announce their position in the traffic pattern. This primer on traffic patterns will help pilots and remote pilots understand the flow of aircraft around airports and help visualize an aircraft’s position in relation to the runway when announced on the radio. This visualization is critical to be situationally aware of aircraft nearby.

Consider the following question:

You are monitoring the local Common Traffic Advisory Frequency (CTAF) when you hear the following transmission: “Athens traffic, Cessna 19916 is left downwind for runway 27, Athens.” Where is the aircraft in relation to the runway?

To answer, we have to understand a few concepts.  Let’s break it down.


What’s In A Name?

Runway 27. It’s not the airport’s 27th runway. It’s not the 27th best runway in the state. And it’s certainly not given the number 27 in honor of the town’s famed sports star’s jersey. Runways are numbered based on the direction they are oriented on a magnetic compass. A compass has 360 degrees. North is 360, East is 90, South is 180, and West is 270. Runway numbers are simply the magnetic direction that the runway is aligned with, minus the last digit. So runway 27 is aligned with 270 degrees (West). This can be confusing if you don’t realize that a single strip of runway is actually two runways because there are two ends. In our example, runway 27 is aligned with West, but the other end of the runway is called runway 9, and it is aligned with East. Same pavement, different directions.

X-Plane 11 KAHN Cessna 172

This Cessna is lined up on runway 27 to takeoff. Thus, it has a heading of 270, or West.


Left Is Usually Right

There are naturally a lot of airplanes around airports. Like bees around a beehive, the coming and going of airplanes would be a chaotic mess if it were not for the traffic pattern. The traffic pattern is simply a rectangular route made up of five legs flown around a runway, typically at 1000 feet above the ground. A standard traffic pattern has left turns, or “left traffic,” but right hand patterns exist at some airports, too.  For right traffic, the legs are named the same, but all of the turns are simply made to the right instead of the left.

X-Plane 11 KAHN Runways

Athens airport has four runways. Runway 2, for example, is aligned with 20 degrees, while runway 20 is aligned with 200 degrees. Just add a 0 to the runway number to get it’s direction.


A Beast With Five Legs

To illustrate the legs of the traffic pattern, picture your airplane taking off from runway 27, meaning you are heading 270 (West). As you lift off and climb straight ahead, you are on the “upwind” leg. After several hundred feet of climbing, a left turn puts you on the “crosswind” leg. Turning left again puts you on the “downwind” leg, now flying parallel to the runway in the opposite direction from which you took off. After flying a bit past the end of the runway, a left turn will put you on the “base” leg. The final left turn lines you up to land on the same runway you took off from on the “final approach” leg.

X-Plane 11 KAHN

This diagram shows a left hand traffic pattern for runway 27 at Athens Airport (KAHN).


Learn The Lingo
Beyond knowing the basic names of the legs, there are a few terms you might hear that could throw you off without a quick explantation.  “Midfield Downwind” simply means on the downwind leg, halfway down the runway.  It’s the common entry point for aircraft into the traffic pattern.  “Abeam The Numbers” is another downwind term.  When flying downwind and the runway numbers (near the end of the runway) are directly off your wing, you are abeam the numbers.  Sometimes a “Straight In” approach is appropriate, where instead of flying any turns or legs of the pattern, the airplane is already aligned with the runway and simply landing from straight out.  There’s a bunch of aviation lingo to pick up on, but those will get you started.


Paint A Picture

Now that the runway orientation is clear along with the flow of the traffic pattern, let’s return to our original question. Here it is again:

You are monitoring the local Common Traffic Advisory Frequency (CTAF) when you hear the following transmission: “Athens traffic, Cessna 19916 is left downwind for runway 27, Athens.” Where is the aircraft in relation to the runway?

One way to visualize the aircraft is to actually draw it out on paper.  You don’t need to make a masterpiece complete with happy little trees.  Just mark a line for the runway based on the direction it’s oriented.  In this case, runway 27 would be a line from left to right (East-West).  If you draw out the legs of the traffic pattern using left hand turns, you’ll find that the left downwind is right below the runway, or in other terms, “South of the runway.”  And there’s our answer.  Another good method for a quick visualization is to use your cell phone.  Perhaps you have yours now.  And it’s likely rectangular…like a traffic pattern.  Rotate your phone so that the right side of it matches the orientation of the runway.  For our runway 27, that’s on its side.  Now the edges of the phone outline the legs of the traffic pattern.  If you mentally superimpose your phone on a compass, figuring out where a left base to runway 13, for example, becomes a little less daunting.  Go ahead, try it out.  Its like a free app that doesn’t even use your data.

Traffic pattern flow sketch

Sketching the runway and pattern is a good start. Eventually, you’ll be able to sketch it in your head.

 

It’s important to paint a mental picture of everything you hear on the radio.  Learn more about situational awareness in a recent blog here.  As a pilot, keeping tabs on the other aircraft around an airport helps you see and avoid them and anticipate their next move.  As a drone operator, any aircraft in the area, whether heard on the radio or spotted visually, should warrant extreme diligence and getting out of the way quickly.  Outside of the airport area, it is much less likely for a drone and an airplane to cross paths.  This is due to the usual 400 foot AGL altitude restriction on drones coupled with a usual 500 foot AGL minimum altitude on aircraft.  There are exceptions, of course, and near the airport for takeoff and landing are the biggest of these.  Practice some traffic pattern awareness and it’ll soon become second nature.

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