I'm not an expert, so I could not explain why that dive is difficult. But the quotes I cited clearly indicate that experts do think that that dive is difficult. See post 42 for those quotes.
You see, the problem is, I'm a pilot. I've looked at the flight path. It's entirely consistent with someone who doesn't like steep bank angles.
I've actually
seen that behavior, first hand, from power pilot friends newly introduced to soaring, who are uncomfortable with the higher bank turns needed to stay in a thermal.
They know, intellectually, that they need to stay steep. But they don't, and then catch themselves... it makes for a very sloppy turn.
That was a very sloppy turn.
Strategically, a good pilot would not have
needed that turn. He'd just have calculated a letdown point and started his descent from there. A straight-in approach gives the maximum time to line up.
If the requirements were to hit a particular wall of the Pentagon, it's more sensible to do the bulk of that maneuvering far away, and then fly a straight-in approach. If the flight is being remote-controlled by a government conspiracy, all these considerations apply in spades. For that matter, if it's a government conspiracy, why not take the time to make another approach? It's not like anyone's going to shoot you down. The military would be in on it.
So. Hanjour finds himself too high, and decides to make a 270 to lose altitude. Not an unreasonable decision. A "heavy" standard rate turn will complete a 270 in about 3 minutes. At higher speeds, though, it's going to be a higher bank than he's used to. Partway through the turn, he realizes he's going to be wide, and increases the bank -- but only to about 45 degrees, and it doesn't stay there. I've seen this before. Due to the futzing around, he has to fly more of a circle to line up.
So, I'm hard-pressed to see either great piloting or even an unusual response to a strange situation. (I'm pretty sure Hanjour hadn't previously done a standard rate turn at those speeds. Standard rate turns aren't needed in cruise, and approaches, which tend to use standard rate turns, are usually flown much slower.)