Originally posted by Gianlupo
Badboy, I've heard of OODA in Andy's articles, he gave a basic description of it, any good reading on the Net to deepen my knowledge of this subject? Thank you, even for this new chart! 
Ok, here is an extract from part one of my series of lectures on the OODA loop.
The OODA loop was originated a number of years ago by a USAF fighter pilot and highly thought of tactician Colonel John Boyd. His OODA loop stands for Observe, Orient, Decide, and Act...this being the decision process that a pilot goes through in solving any given BFM problem during an engagement. For example, if you see you opponent change his flight path with an aileron roll, you are in the “Observe” phase of the loop. You then need to comprehend what effect your opponents changes will have on the situation, so now you are in the “Orient” phase. Now you need to make a decision from the many options available, and while doing that you are in the “Decide” phase. Finally, you need to execute that decision with a manoeuvre of your own, so you are in the “Act” phase of the loop, and so it continues.
When I teach this to flight sim’ pilots I prefer to call it the "Boyd Cycle" (when I call it the Boyd loop, some folk expect it to involve a loop manoeuvre) and I explain that the pilot who consistently completes the cycle faster gains an advantage that increases with each cycle. Because the gains are additive the slower pilot becomes increasingly slower by comparison and therefore less effective until, finally, he is overcome by events.
So how does this theory apply to tactics in air combat? I've worked out some examples, but firstly, although gains in the loop can be made in any of the phases, I’m just going to consider just the "Action" phase. For example there is a large variation in roll rate for WWII aircraft and so those that have higher roll rates allow the pilot to complete the "action" phase more quickly, thereby allowing him to stay inside his opponent’s Boyd loop. This can be very powerful. For example, it is possible to defeat an aircraft with superior level turn performance, from a neutral position and ending with a guns solution, by using just a roll rate advantage. When inexperienced pilots see this, they are amazed that they have an aircraft that can out turn their opponent, yet they can't kill it. The reason is that the pilot of the aircraft with the superior roll rate can use manoeuvres that take advantage of the roll rate and increase their advantage incrementally every time they use it. Here is a concrete example.
Suppose we have Aircraft A and Aircraft B and suppose that the Aircraft A can turn at 18dps and has a 2dps turn rate advantage over Aircraft B that turns at 16dps. Normally, 2dps would be considered a decisive advantage in Air Combat, so Pilot A would be expected to win. However, suppose pilot B had a 120dps roll rate and that Pilot A has a 60dps role rate. Now consider what happens in a turn…
A and B are turning hard for 10 seconds say, and so pilot A gains 20 degrees on pilot B and thinks he’s winning the fight. But now B rolls 120 degrees and then continues turning. To follow him pilot A will need to roll for 2 seconds, but pilot B actually completed his 120 degrees roll in one second, so he was able to continue his turn for a full second while pilot A was still completing his roll, at 16dps that means pilot B just gained back 16 of the 20 degrees. Ok, I hear you thinking, Pilot A is still 4 degrees ahead, all he now needs to do is keep turning for the kill. Not so fast… The moment pilot B sees pilot A complete his roll and begin to turn into him again, pilot B repeats his previous 120 degree roll in another direction and now gains another 16 degrees. At the end of that pair of manoeuvres, pilot B with the inferior turning aircraft will be 12 degrees farther around than his opponent, and he will gain another 16 degrees every time he does it. Of course, I only picked those numbers because they were easy to work with, they aren’t important, it is the principle that counts. As Boyd said "Time becomes the critical determinant of combat advantage".
After all that, we have still only been discussing the “Act” part of the cycle. When you consider the other parts of the cycle, there are other factors that have an effect on the outcome. For simulation pilots the “Observe” phase is influenced by the viewing system used, the icons, radar, and even the game resolution all provide different visual cues. Their interpretation can lead to different perceptions and estimates of the combat situation. So “Orient” is about understanding what you see, and different levels of comprehension will compel pilots to make different decisions. Inexperienced pilots are more likely to use pure "G for brains", and pull directly into the bandit, while pilots better versed in the subtleties of air combat are likely to have a more complete three dimensional perspective, and thus be able to find more efficient solutions to BFM problems. So the “Orient” phase is about understanding the situation you are in, the implications of the bandits actions, and what you need to do about it, and there may well be several options. That of course leads to the “Decide” phase, and has other influences, for example how many solutions there are, how much fuel or ammo you have remaining, the proximity of other aircraft… and so on. Each phase takes some time and Boyd’s proposition was that the successful pilot will be able to process his OODA loop more rapidly than his opponent. In his own words the successful pilot would "get inside his adversary's loop", thereby forcing the opponent to always react defensively. Boyd once said while describing what it was like to operate inside his opponent’s OODA loop: “It’s like they’re moving in slow motion.” And there are many who can confirm, that is exactly what it is like to fight new pilots online…
Hope that helps...
Badboy
