[dragonwriter]

> NORAD probably wanted to clear some airspace to better track the missile

I can't see any way planes in Western US airspace could possibly interfere with tracking an NK launched ICBM, even by clutter, except maybe in the last minutes of the terminal phase of warhead descent at which point any defense (active or civil or both) would already have to have been committed to do any good.

Grounding planes is to mitigate risk to the people on the planes, and maybe to clear lines of fire for anti-missile systems (which is mostly about protecting people who aren't on the planes, but incidentally also protects those on the planes, too.)

[betterunix2]

Like I said, what if one of those planes had a malfunctioning transponder? It is a somewhat stretched scenario, but the NK military might have gotten bold and decided to shoot a missile all the way to the boundary of US territorial waters or airspace. In the middle of nervously tracking a missile that seems to be headed directly toward the west coast, NORAD suddenly sees another object that looks just like an airplane heading toward LA or SF, but it is not identifying itself. Now NORAD personnel have to take time to figure out if this airplane is just a malfunctioning civilian plane or some kind of NK attack.

Sure, NORAD probably tracked the plane from whatever airport it departed from, but during the missile test they probably want to have their personnel focus every second of their attention on the missile and not on checking some flight path.

[bubbleRefuge]

Maybe it was because we have a secret Anti-Ballistic Missile system that "throws darts" at inbound missiles and we don't want any planes in the cross fire ?