Just as there are intersections and specific rules for automobiles, the procedure for airplanes is even more intense. Automobiles use only a lateral axis for movement whereas airplanes have three axes: longitudinal, lateral, and vertical. Hence, there is much more that goes into the traffic flow of aircraft.
Every airport has an “unspoken” basic traffic pattern that pilots should follow. In and around airports where there is no control tower, there is much more freedom to modify this taught pattern; however, it is imperative that pilots announce their position over the airport’s frequency via radio. Conversely, if an airplane is approaching or departing from a controlled airport, it is imperative that they follow a specific pattern. Traffic patterns can extend off the right side of the runway, or they might extend off the left side. The Federal Aviation Administration’s recommended altitude for most traffic patterns is 1,000 feet above ground level.
Just what is this pattern? Picture a rectangular perimeter wherein the runway runs alongside at least 60% of the length of one side. Each side is known as a leg. Once an aircraft takes off, they climb out on the Departure leg. At the end of the Departure leg, the pilot can either leave the traffic pattern, or they can turn to the next leg, which is known as the Crosswind leg. This leg runs perpendicular to the departure leg and is the first short side of the rectangular perimeter. Pilots then turn from Crosswind leg to the Downwind leg, which is opposite and parallel to the runway, proceeding past the end of the runway a short distance until the pilot turns to the Base leg. The pilot typically would contact the control tower before the turn to Base leg. It is on Base leg that the pilot is setting up the aircraft for landing, i.e. descending and lowering flaps. At this point, the landing runway should be approximately at the pilot’s visual 10:00 position. The Final leg is the path wherein the airplane descends to the runway for landing. Procedure for otherwise incoming aircraft into the traffic pattern is suggested on Downwind at an approximate 45-degree angle.
Ultimately, it is difficult to communicate this visual simply in words; therefore, for a visual from the Airman’s Information Manual, access this page.