An airfield traffic pattern is a standard path followed by aircraft when taking off or landing.
At an airport, the pattern (or circuit in the Commonwealth of Nations) is a conventional standard path for coordinating air traffic. It differs from so-called "straight in approaches" and "direct climb outs" in that aircraft using a traffic pattern remain in close proximity to the airport. Patterns are usually employed at small general aviation (GA) airfields and military airbases. Most large airports avoid the system, unless there is GA activity as well as commercial flights. However, a pattern of sorts is used at airports in some cases, such as when an aircraft is required to go around.
Pilots prefer to take off and land facing into the wind. This has the effect of reducing aircraft speed over ground and hence reducing the distance required to perform either maneuver.
The exception to this rule is at Alpine airports, 'Altiports' where the runway is on a severe slope. In these instances, takeoffs are made downhill and landings uphill, with the slope aiding in acceleration and deceleration.
Many airfields have runways facing a variety of directions. The purpose of this is to provide arriving aircraft with the best runway to land on, according to the current wind direction. Runway orientation is determined from historical data of the prevailing winds in the area. This is especially important for single-runway airports that don't have the option of a second runway pointed in an alternate direction. A common scenario is to have two runways arranged at or close to 90 degrees to one another, so that aircraft can always find a suitable runway. Almost all runways are reversible, and aircraft use whichever runway in whichever direction is best suited to the wind. In light and variable wind conditions, the direction of the runway in use might change several times during the day.
The Pilots Operating Handbook (POH) displays the maximum demonstrated crosswind component for the aircraft, this figure is based on a pilot with average experience and, in most cases, could easily be exceeded by an experienced pilot. Many pilots set their own crosswind limitations based on their skill. High-wing aircraft are more difficult to control in crosswinds compared to low-wing aircraft.