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For the new glider pilots, it is best to become proficient using one of the above methods first, and then experiment with other methods. As an additional note, thermals often deviate markedly from the conceptual model of concentric gradients of lift increasing evenly toward the center. For instance, it sometimes feels as if two (or more) nearby thermal centers exist, making centering difficult. Glider pilots must be willing to constantly adjust, and recenter the thermal to maintain the best climb. 

In addition to helping pilots locate lift, other gliders can help pilots center a thermal as well. If a nearby glider seems to be climbing better, adjust the turn to fly within the same circle. Similarly, if a bird is soaring close by, it is usually worth turning toward the soaring bird. Along with the thrill of soaring with a hawk or eagle, it usually leads to a better climb. 

## Collision Avoidance 

Collision avoidance is of primary importance when thermaling with other gliders. The first rule calls for all gliders in a particular thermal to circle in the same direction. The first glider in a thermal establishes the direction of turn and all other gliders joining the thermal should turn in the same direction. Ideally, two gliders in a thermal at the same height or nearly so should position themselves across from each other so they can maintain best visual contact. [Figure 10-12] When entering a thermal, strive to do so in a way that does not interfere with gliders already in the thermal, and above all, in a manner that does not cause a hazard to other gliders. An example of a dangerous entry is pulling up to bleed off excess speed in the middle of a crowded thermal. A far safer technique is to bleed off speed before reaching the thermal and joining the thermal at a “normal” thermaling speed. Collision avoidance, not optimum aerodynamic efficiency, is the priority when thermaling with other gliders. Announcing to the other glider(s) on the radio that you are entering the thermal enhances collision avoidance. [Figure 10-12] 

Different types of gliders in the same thermal may have different minimum sink speeds, and it may be difficult to remain directly across from another glider in a thermal. Avoid a situation where the other glider cannot be seen or the other glider cannot see you. Radio communication is helpful. Too much talking clogs the frequency, and may make it impossible for a pilot to broadcast an important message. Do not fly directly above or below another glider in a thermal since differences in performance, or even minor changes in speed can lead to larger than expected altitude changes. If sight of another glider is lost in a thermal and position cannot be established via a radio call, leave the thermal. After 10 or 20 seconds, come back around to rejoin the thermal, hopefully with better traffic positioning. It cannot be stressed enough that collision avoidance when thermaling is a priority! Mid- 

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air collisions can sometimes be survived, but only with a great deal of luck. Unsafe thermaling practices endanger everyone. [Figure 10-13] 

## Exiting a Thermal 

Leaving a thermal properly can also save some altitude. While circling, scan the full 360° of sky with each thermaling turn. This first allows the pilot to continually check for other traffic in the vicinity. Second, it helps the pilot analyze the sky in all directions to decide where to go for the next climb. It is better to decide where to go next while still in lift rather than losing altitude in sink after leaving a thermal. Exactly when to leave depends on the goals for the climb—whether the desire is to maximize altitude for a long glide or leave when lift weakens in order to maximize time on a cross-country flight. In either case, be ready to increase speed to penetrate the sink often found on the edge of the thermal, and leave the thermal in a manner that does not hinder or endanger other gliders. 

