I'm not trying to explain it, I can only tell you that based on what we know the X-43a doesn't fit what the US Navy pilot has seen. You seem keen to debunk it being anything other than a conventional plane. I could at least get on board if you were saying it was something like a Lockheed Martin black project with advanced technology we don't yet know about, but a rocket plane is literally dumb.
I don't believe the US Navy pilot's account, or elements of it, I don't believe he saw a tic-tac shaped thing, or that it was there, nor do I believe he saw something hovering above the water, moving about in ways in which he described - it's worth reminding you that there's absolutely no evidence whatsoever of this.
I believe he saw *something* though, and he's either modified his story to make it sound like there's more to it, or he was confused and ended up fooling himself into believing what he saw was something far more elaborate.
how does it not matter if the speed and altitude they're describing is NOT the speed and altitude of the X43-A? How could the X43-A be what they saw, if it wasn't at that altitude, and doing a different speed?
It's clear *something* was going on in the area, and it's clear that somebody saw something, because multiple ships saw an object, or objects, so I'm not doubting that there was nothing there, I am however doubting the account of the pilot.
I'm doubting the account of the pilot, because what he claims he saw had performance characteristics that would probably require physics and material breakthroughs which 15 years later, show no sign of existing, anywhere. No conceptually, not experimentally. Nowhere does anything exist that can do what the pilot says he saw.
So, extraordinary claims require extraordinary evidence, and unfortunately there is none whatsoever, other than a recording from the TGP on the F18, which shows what appears to be the TGP losing it's track on the object due to it being at it's limits, rather than the object flying off at a tremendous speed, so I cast doubt on that too. (that's not my opinion, that's the opinion of another pilot)
It seems reasonable to speculate, that because Nasa were testing the X43-A in the same area at the same time (because that is definitely true) that it caused an element of confusion, to the point where what we seen was interpreted as something else. Combined with perhaps instrumentation error or operator error - could offer an explanation for what happened. Add to that, the Navy pilot spinning his story for attention, and it might explain it.
I certainly don't think you can rule out the X43-A, because it was traveling at around Mach 10 in the vicinity of the group at the same time (regardless of altitude, or rocket plume), that fact alone should raise concerns as to whether it could actually be the culprit, in the absence of any other theory (because there aren't any really)