I was actually at Luke that night (I’m a civilian). An F-16 pilot I spoke to about it told me that it was probably a flight test of an F-16 following engine maintenance or repair. He said that after work is done on the engines, the pilots really put the planes through their paces to make sure things are working right - including high speed, steep climbs.
Those birds can make a heck of a lot of racket and put out a pile of plumeage,, cool watching ‘em climb like that..
Still doesn’t seem right. If he had just slammed on his afterburners, I still wouldn’t expect a trail like that unless he had a serious engine problem.
My personal guess was that it was a high altitude weather rocket, doing something confidential. Since you couldn’t erect a gantry at Luke without everybody seeing it, it was probably relatively small.
I know that NASA has been keeping an eye on the thermosphere, which has been acting very odd of late, what with the long period of inactivity of the Sun. But a small rocket going that high would imply an advanced fuel or engine.
Again, all guesswork.