Plein Air is traditionally a process of painting outside, capturing fleeting light and colors in the outdoors. In this case, it's rug hooking outside, trying to catch the light and colors before they change. I take a bin full of colored fiber that I think will reflect the scene I am hooking, a comfortable chair, my hooking equipment and some liquid refreshment, and off I go.
I rarely sketch these out beforehand in my sketchbook, because then I tend to get too detailed and the delay changes the light and the emphasis I want in the piece before I get to the backing to hook! So instead I sketch directly on my backing and hook a small piece of colored strips in the areas I want those colors to go. Then I have a reference if the light changes dramatically on me, or I have to call a halt before I'm finished.
It takes an hour to hook an area the size of my hand, so the original plein air studies are small - usually 2 hours of hooking or less. I later take them inside and decide whether to create full size studio pieces from them, or not. Sometimes I do not. Oftentimes the studio pieces sell quickly. Sometimes the actual plein air studies have more of an immediacy to them and attract people's eyes.
However people view them, I learn a lot about light, color, and quick decision making as I'm hooking, whenever I do one of these pieces.