What is reflection-in-action?

Much of our daily life consists of spontaneous, intuitive actions which we simply do. Similarly, much of work-life consists of simply knowing and doing. An example is driving, where knowledge is tacit, and is expressed in actions. Reflecting upon our actions is a way of revealing tacit knowledge. Reflection during action is reflection-in-action.
Stimulated by surprise, they turn thought back on action and on the knowing which is implicit in action. ... Skillful action often reveals a "Knowing more than I can say" (p. 50).
Reflection-in-action may be considered to be applied mindfulness, where the emphasis is away from analytical thinking. Reflection-in-action distinguishes between "thinking processes" and "non-logical processes which are not capable of being expressed in words or as reasoning" (p. 51). These occur within the context of actions
The process spirals through stages of appreciation, action, and reappreciation. The unique and uncertain situation comes to be understood through the attempt to change it, and changed through the attempts to understand it (p. 132).
The Challenge of Reflection
Schön spent considerable time discussing the difficulties of reflection-- for individuals, professions, and society. We are challenged by our education and institutions, and student/teacher relationships rarely probe reflectively. In addition, we exist in a culture which emphasizes Technical Rationality foremost.
Nevertheless, because professionalism is still mainly identified with technical expertise, reflection-in-action is not generally accepted--even by those who do it--as a legitimate form of professional training. ...For them, uncertainty is a threat; its admission is a sign of weakness (p. 69).
When a practitioner does not reflect on his own inquiry, he keeps his intuitive understanding tacit and is inattentive to the limits of his scope of reflective attention.... He is unlikely to get far unless he wants to extend and deepen his reflection-in-action, and unless others help him to see what he has worked to avoid seeing (p. 283).
Surprise, which is essential to learning, is inimical to smooth organizational functioning (p. 327).
Summary
Professionals who cultivate the ability to reflect-in-action may be said to be in their work, rather than do their work. As if they were immersed in the complex system, rather than technically manipulating it from outside. Reflecting-in-action generates professionals who re-create themselves and their work as they work. Schön himself summarized it best:
When a practitioner becomes a researcher into his own practise, he engages in continuous self-education... Practise itself is a source of renewal.... Error becomes a source of discovery, not self-defense (p. 299).