The upwind leg is that leg immediately following takeoff and is aligned with the runway heading. It starts from the point of takeoff and ends at the point where you make the turn to crosswind, and follows that line created by extending the runway centerline.
When flying in the pattern, you must determine the point at which to make the turn to crosswind. The guidelines are to make sure that it?s beyond the departure end of the runway and that the aircraft is within 300 feet of the traffic pattern altitude (TPA).
The crosswind leg is that leg following the upwind leg. It is perpendicular to the runway heading. It starts at the point you finish your turn from upwind, and ends at the point you begin your turn to downwind. Upon reaching the traffic pattern altitude and when in the correct position, the pilot should begin a level turn to downwind.
The downwind leg is that leg immediately following the crosswind leg. It starts at the point you finish your turn from crosswind and ends at the point you being your turn to the base leg. It is parallel to the runway and flows in the opposite direction of your intended landing. It is during this leg that you complete your landing checklist. In many cases, it?s also the time that you begin your descent. As a general rule of thumb, you begin your descent when abeam the arrival end of the runway. (ie: "abeam the numbers")
When flying downwind, you must determine when to begin your turn to base. General guidelines are to begin your turn when the line between your aircraft's position and the arrival end of the runway form a 45 degree angle. If another aircraft is ahead of you in the pattern on final, you should extend the downwind leg until the line between your aircraft and the other aircraft from a 45 degree angle. You must also consider the wind conditions. You should ensure that you turn at a point such that you can achieve a safe, gradual descent to the touchdown point.
The base leg is that leg following the downwind leg. It begins at the point you complete your turn from downwind and ends at the point you begin your turn to final. It is perpendicular to the runway heading. Having started the descent on downwind, this is a descending leg.
Final Approach is the last leg of the pattern. It's that leg immediately following the base leg. It begins at the point you complete your turn from base and ends at the point your aircraft touches down on the runway. It follows that line created by extending the runway centerline. This is the most critical leg as it?s where you much continually judge your height and airspeed to touchdown at the desired point on the runway.
Determining the Pattern Altitude (TPA)
The standard Traffic Pattern Altitude (TPA) for small GA aircraft is 1000 ft AGL. For turbojets, the standard is 1500 ft AGL. However, the TPA is set by the airport and can vary on occasion. To find out the actual altitude, you should reference an Airport / Facilities Directory (A/FD) which contains information pertinent to that airport or search online to find this information. It?s readily available in several locations.
Determining the Pattern Direction
The Airport diagram or other official publications will list the pattern direction for each runway at publicaly accessable airport.
Entering the Pattern
There are many ways to enter a pattern at an uncontrolled airport, the most common and accepted point is at pattern altitude and at a 45 degree angle from the downwind with the entry point about mid-field. At controlled airports (TWR/APP staffed) the pattern entry will be given as a part of the clearance to enter the pattern.