The flight path and the aircraft's inertia ARE material. Anyone who has snapped an aircraft going vertically upward knows. It will not establish a stable downward spin until its inertia is spent, has rolled over and started down. The entry into a spin at stall speed horizontally and level is a whole lot different than going horizontally, vertically upward or downward with lots of inertia. Additionally, the control placements after entry can effect the shape and speed of the rotation. In this case, we have no idea what the pilot was doing with the controls after it rolled right. The ventral fins on the Viper would very likely effect it....they sure do on the Navy's T38C which we found would do an unrecoverable flat spin without them and the strips on the nose cowling (this I have firsthand knowledge of). Also, a stable spin is not usually considered stable until it has rotate vertically downward a minimum of three turns.

I do not think anyone is picking on the pilot or the fellow reporting the incident. I hope you remember it was HIS post and request for evaluation of the video and I think everyone's opinion of the video is as valid as yours. No doubt it could have been a control surface problem, but in the absence of more post-accident specifics to the contrary, we have a dirty heavy airplane with a very high angle of attack and wing loading with a pilot possibility pulling back harder than normal to secure a gear (unless he just decided to do a dirty loop seconds after the nose gear went down). There was no evidence of any control issue prior to the abrupt roll to the right. Unless he reports to us some more specifics about a broken linkage or strip gear, I have to stick with what appears, in my opinion, the probably cause which includes more the the shape of the rotation. If anyone wants to video his Viper doing the exact same maneuver and post it here that might give us some more info too.