What is the standard direction for a traffic pattern at an uncontrolled or non-towered airport?
When aviation literature mentions "the standard traffic pattern", it's usually a left-hand counterclockwise pattern; regardless of wind direction, the runway will always be to your left side and you make left turns to follow the pattern through crosswind, downwind and base legs. This is the default pattern direction when there are no overriding signals.
However, this is only the default, and airports are free to change the procedure as needed to comply with local terrain or development. An airfield near a neighborhood to its east, for instance, may require that traffic circle around the west side of the airport; therefore this airfield's 17/35 runway will require a left-hand pattern when using runway 35, but a right-hand pattern when using runway 17.
When an airfield establishes a non-default traffic pattern, they must provide this information to pilots in a readily-visible manner. The standard recommended (though not required) set of runway and pattern indicators is known as the segmented circle, so called because its most visible identifying feature from a distance is a 75-foot circle of dashed lines:
In the center of the circle as pictured is the runway direction indicator aka the tetrahedron; this will indicate which strip of asphalt to use and which direction to take off and land on it (the narrow end points in the direction that planes should take off and land).
Off to one side is the windsock, which is the only piece of equipment that is required at any airfield; it indicates approximate wind speed and direction. FAA guidelines for the sock say it should reliably turn to the wind direction at 3 knots, begin to inflate at 5 knots and be fully extended at 15. The windsock can replace the tetrahedron in the center of the circle; in that configuration you would simply approach the airfield using the runway closest to the direction in which the tip of the windsock is pointing (if winds are calm and/or the airfield has multiple runways, the tetrahedron is preferable).
On the ground just outside the segmented circle are L shapes; these are the pattern indicators, and point in the direction of the base leg when approaching the runway from that end (so if you're following the pattern, the end of the L should be pointing at you before your turn to final).
So, the circle in the above picture tells aviators several critical things without any human (or computer) having to relay the information vocally:
- The approach direction is from the upper right to the lower left of this picture.
- The wind is roughly in line with the runway, so no crosswind landing procedure is required.
- Winds are very strong (the windsock is fully extended which indicates wind speeds in excess of 15 knots) so ground speed will be much lower than IAS at takeoff and landing.
- Most relevant to your question, airfield traffic should be on a right-hand pattern at this time; if the winds and thus the runway in use were opposite, traffic would use a left-hand approach.
FAR 91.126(b)(1) states that all turns in the vicinity of an airport in Class G airspace should be made to the left unless otherwise marked. That includes the traffic pattern.
Title: Non-Towered Airport Flight Operations
9.1 Left Traffic. Use of standard traffic patterns (left turns) for all aircraft and CTAF procedures by radio-equipped aircraft are required at all airports without operating control towers unless indicated otherwise by visual markings, light gun signals, airport publications, or published approach procedure. It is recognized that other traffic patterns (right turns) may already be in common use at some airports or that special circumstances or conditions exist that may prevent use of the standard traffic pattern. Right-hand patterns are noted at airports on an aeronautical chart with an “RP” designator and the applicable runway next to the airport symbol.