... the way he did in the final episode. (Note: Wow, two topics in one day from someone who's a major lurker. Sorry if there's a topic for this, but I didn't see any)

Anyways, I admit I wasn't sure of the logic of this either... until I read someone's explanation on deviantART. This next part isn't mine, it belongs to Kawa-Misuterii and deviantART and I'm only using this to give an explanation to confused fans like I was:

"One last thing.............don't kill me, but I do believe Aang let Katara go. There's a spiritual difference between caring about something or someone, and being attached to something or someone, and Aang wouldn't have been able to go into the Avatar State in Ba Sing Se if he didn't let her go. The fact that his chakra was locked was because Azula physically screwed something up with his body with the lightning bolt(remember the chakras are all based in different areas of the body) So it only makes sense that he manages to right himself physically, thus inducing his chakras to align themselves."

Ok just what I thought about this is.

The whole chakra thing has to do with energies in the body and if you manage to open all of them you can control the avatar state remember that's why he went to the guru guy.

The spiritual thing they were going on about and how he has to sacrifice that for the good of the world were his beliefs about all life being sacred.

And I agree with the whole azula damaged something in him which blocked his chakra and stopped him from using the avatar state but that is was fixed when he hit his spine.

Thats just my opinion.

Wait. You guys do realize that you discovered the long lost loophole in what the guru said!?

It's been said since Crossroads that there was a loophole, and that was it! The guru wanted the Avatar to detatch himself from the world, but yet he can't because his duty is to the world. Love is spiritual and an attatchment, and when Aang said that his chakra was blocked because of Azula in The Invasion, he was right! When the rock hit him in that spo, it righted whatever Azula's damage was, thus making him master the Avatar State.

I'm too tired to post my usual 2-3 paragraph detailed description of something, but the guru's way was not the only way to learn to master the avatar state... I doubt the past avatars had a guru tell them all that stuff.

Just a lazy explanation, I still think he subconsciously went into the avatar state when his back got jabbed as it reawoken the last point in time when he was actually in the avatar state. Because he was far more mature and had a better grip on the elements he was able to control the avatar state once he was in it. Then after he learned to control it while he was in it, getting in and out of it was no problem (we see when he makes the water rise he finally has full control). I don't think his chakra's had anything to do with him going into and mastering the avatar state personally

There are really two major reasons, in my opinion, that Aang was able to access the Avatar State fully. I don't think it has anything to do with letting go of Katara. Logically, that couldn't make sense considering how hung up on her he was at Ember Island.

Reason 1 would be the Giant Lion Turtle. If you pay attention, you see that the Turtle touches Aang in both the centre of his chest and the top of his head. The centre of his chest is the precise location of the Heart Chakra, which is the centre of the body. It not only governs love and compassion (Katara) but it also controls the circulation of energy (Chi) throughout the entire body. Without the balance of the Heart Chakra, the energy of the body isn't balanced.

The top of the head is commonly referred to as the Crown Chakra, or Sahasrara. It's symbol is the 1000 petal lotus and it represent complete spiritual awarenss and connection to the Universe. It's purpose is anything but earthly and represents connection to the world beyond, or "heavens." It also represents spiritual awarenss.

But bending the energy within Aang's body, the Turtle must have opened and cleared the heart and crown chakras. Allowing for full mobility of energy and chi, not to mention spiritual awareness and thusly, a connection to the Avatar State.

Let's not forget that Aang touched Ozai in the same places the Turtle touched him. Allowing Aang to bend the energy (5th element) in Ozai's body, negating it from existence.

Reason 2 would be a lot more simple. If you recall, it was Roku who told Aang that the Avatar State is merely a defense mechanism. Perhaps, when Aang crash into the stone and hit his wound against the jagged piece of rock, it subconsciously brought back his near-death crisis and sent his Avatar Energy on overload.

direct pressure to the point of injury...

the whole time i was saying that redirecting lightning would do the trick

but what if when faced with the thought of dying aang let go of katara at the same point when he was thrown into the wall