Airfield Traffic Pattern - Layout

Layout

Traffic patterns can be defined as left-hand or right-hand, according to which way the turns in the pattern are performed. They are usually left-hand turns because most small airplanes are piloted from the left seat (or the senior pilot or pilot-in-command sits in the left seat), and so the pilot has better visibility out the left window. Right-hand patterns will be set up for parallel runways, for noise abatement or because of ground features (such as terrain, towers, etc.). In the USA, the non-standard (i.e. right-hand) patterns are noted in the Airport/Facilities Directory or on a sectional chart; in other countries they may be indicated in that nation's similar document, e.g. Canada Flight Supplement. Unless explicitly indicated otherwise, all traffic patterns at non-towered airports are to the left.

Helicopters are encouraged, but not required, to use an opposite pattern from fixed-wing traffic due to their slower speed and greater maneuverability.

Because the active runway is chosen to meet the wind at the nearest angle (with take-offs and landings upwind), the pattern orientation also depends on wind direction. Patterns are typically rectangular in basic shape, and include the runway along one long side of the rectangle. Each leg of the pattern has a particular name:

• Components of a Traffic Pattern. Fig. 4-3-1 from FAA AIM.

• Upwind leg. A flight path parallel to and in the direction of the landing runway. This can be above the runway, as in a "low and over" or when practicing a "missed approach," or offset to the upwind side as when inspecting the field prior to landing.
• Crosswind leg. A short climbing flight path at right angles to the departure end of the runway.
• Downwind leg. A long level flight path parallel to but in the opposite direction of the landing runway. (Some consider it to have "sub-legs" of early, mid and late. Certainly a plane giving a position report of "mid-downwind" can be visually located easily.)
• Base leg. A short descending flight path at right angles to the approach end extended centerline of the landing runway.
• Final approach. A descending flight path in the direction of landing along the extended runway centerline from the base leg to the runway. The last section of the final approach is sometimes referred to as short final.
• Departure leg. The climbing flight path along the extended runway centerline which begins at takeoff and continues to at least 1/2 mile beyond the runway's departure end and not less than 300 feet below the traffic pattern altitude. It is a special case of an upwind leg.

The names of the legs are logical and based on the relative wind as seen looking down a runway facing into the wind. An aircraft flying upwind heads into the wind, flying crosswind heads across the wind, flying downwind heads in the direction of the wind just like blown smoke.

While many airfields operate a completely standard pattern, in other cases it will be modified according to need. For example, military airfields often dispense with the crosswind and base legs, but rather fly these as circular arcs directly joining the upwind and downwind sections.

• Standard airport traffic pattern. Fig. 4-3-2 from FAA AIM.