As we have seen, Boyd thought highly of what appears to be agility, but never used the word (with one exception) and never defined it in print. Several years after he quit distributing updated charts in 1986, he did change the “Theme for Vitality and Growth,” chart 144, to include “agility,” but he still didn’t define it.

While giving his presentations, though, Boyd would talk about agility, and he usually divided it between physical and mental (you cannot, as he would slyly remark, have “moral agility,” because that would be no morals at all!)

So let’s start with physical agility, which is what most people mean by the word: a running back dodging a block and jumping a tackler; a point guard threading a way to the net. As far as I know, the use of the term in modern military strategy began with the analysis of air-to-air fighters in the 1960s (I could be wrong, but it’s not important to Boyd’s ultimate concept), which Boyd encapsulated as:

The ability to shift or transition from one maneuver to another more rapidly than an adversary enables one to win in air-to-air combat. (Strategic Game, 42)

A “maneuver” is a change in airspeed, altitude, or direction in any combination. Climbing, diving, accelerating, decelerating, turning, turning-while-climbing, diving-and-accelerating-while-turning, and Boyd’s favorite: climbing-or-turning-while-(rapidly)-decelerating. These are all maneuvers. “Agility,” then, is the ability of the aircraft to change from doing one of these to doing another. Boyd claimed in the quote just above that such agility is the key to winning dogfights.

Well, that, plus be able to make such changes more rapidly than an opponent. Physical agility implies a time element. It is not the same as “flexibility” or “maneuverability.”  It is possible, in fact, to be more maneuverable but less agile, like the MiG-15 compared to the F-86.

If we’re talking about machines, say, the types of fighter aircraft that Boyd flew, we can give a mathematical description of agility that depends on such factors as the responsiveness of the aircraft’s control system, the area of the wing, power of the engine, size of the control surfaces, stability, and other purely physical factors.

Physical agility can provide a huge advantage if the pilot is able to use it. When we talk about the aircraft transitioning from one maneuver to another, it is because the human in the cockpit made the decision to change maneuvers, which includes what maneuver to change to and when to start the transition.

You can start to see the original idea for the OODA loop taking shape: the pilot observed what was going on, figured this into the understanding of how the situation was unfolding, selected a new maneuver (made a decision), and attempted to execute it.

One caution, however. In real person-vs-person combat, as those of you in the martial arts well know, you can’t afford to wait to see the full impact of your last action before you get around to selecting the next one. It’s much better to think of orientation controlling action—in as near real time as you can manage—via the implicit guidance and control link. As Boyd notes near the end of Patterns:

In a tactical sense, these multi-dimensional interactions suggest a spontaneous, synthetic/ creative, and flowing action/ counteraction operation, rather than a step-by-step, analytical/ logical, and discrete move/countermove game. (chart 176)

But the basic idea is sound: The human has to have a mental picture/model of the unfolding situation, and based on this, make decisions to shape or respond to that situation. If the situation is changing quickly, these changes need to be spotted quickly, understood quickly, and actions selected quickly. Agility.

So even though we started with physical agility, as soon as we introduce human beings into the picture we’re into mental agility, of which more in the next post.