<p>Zaheer moves his weightless body as fast as he can bend the air around him, so I doubt he'll break the sound barrier. We may be looking at a top speed of around 12-14 km/minute. No, really. </p>

He's pretty fast when he fly past Korra in their fight.

<p><i>When your girl's sentenced to die</i> </p><p><i>There's no better time to fly</i> </p><p><i>Think of all the peace you'll find</i> </p><p><i>With the poison in her mind...</i> </p><p>I'm sorry, I really shouldn't. But it was <i>right there</i> for me. </p>

We also have to account how fast can he comfortably fly with no protective gear on? There is a reason why early pilots wore goggles while flying.

<p>Some more info. </p><p>Aang could make a tornado strong enough to move a giant boulder Bumi tossed at him, the tornado would need to be 300mph, he could run on water and this one was hard to find the speed but it ranges from 30m/s to 215m/s, and he could run from one mountain to another in two minutes. Aside from reacting to lightning that is approximataly mach 294, but this one is a little controversial. Now i believe Zaheer is faster than Aang with his flight, so at least speed of the sound sonic i think he is. </p>

He was sure as hell bookin' it when Korra was on his ass...but Hasdi's probably right nonetheless.

<p>Well, there's something else to consider here: Zaheer isn't just moving the air around him. He has, for all intents and purposes, <i>become</i> the air around him. He doesn't produce a tidal wave of air around him; from the shots I've seen, it's simply reacting like he's a gust of wind. My hypothesis, then, is that airspeed and drag as we know it wouldn't affect him, and while it defies what we know of even Avatarasya physics, it still seems relatively reasonable. </p>

<p>Zaheer's speed was incredible, but I wonder how fast he could have been if korra hadn't been poisoned. And what about atitude? How high could he go into the shy?    </p>

<p>The gusts of wind generated as he passed by korra were enough to actually move her, so he was fast. It would have been really cool to see flying zaheer vs ozais air ship fleet, </p>

<div class="quote"><i> <p>Flying Fury wrote: Zaheer's speed was incredible, but I wonder how fast he could have been if korra hadn't been poisoned. And what about atitude? How high could he go into the shy?    </p> </i></div>
<p>As high as his body could handle, probably. It's not a clear-cut answer, instead it depends on the conditions implied by the question. </p><p>Is it "how high can he go without permanent health problems"? "How high can he go without having to slowly adjust"? "How high could he go if he didn't worry about surviving the trip"? Etc. </p>