> "The plane had been cruising at 17,000 feet until 1:21 p.m., when it dropped approximately 250 feet in 10 seconds. It then climbed approximately 400 feet in about eight seconds."

> The last sentence suggests that they were actively trying to get back to their assigned altitude of 17,000′.

I believe the author is implying that if the pilots attempted to maintain speed rather than altitude, the aerodynamic stall wouldn't have occurred - if they descended below 12000', the icing would be reversible.

Right, it was that bolded "400'" climb that clearly is what hes pointing at - as the ice caused the drop, then the pilot sharply climbed, then ice-stall, causes plane to yaw pilot corrects the wrong direction causing spin - all in the course of what seems like ~30 seconds?

It seems that the pilot error here was to fly into severe icing, or to staying in icing conditions beyond what the aircraft was capable of handling.

Or to not recover properly from icing.

At the end he says...

"So… icing by itself likely cannot be the cause of the recent accident in Brazil."

Airline accidents almost always have multiple causes. Only when all the swiss cheese slices line up holes can the accident slip through.

Mentour Pilot four years ago on superstall (deep stall): https://www.youtube.com/watch?v=Kg6jV5mkf-8&t=0s

T-tail aircraft (like this one!) are at risk. ATR-72 specifically mentioned.

Thats why I specifically said with potential pilot error (I was going to say mechanical failure, but that is highly less likely given the age of the aircraft.)

>"Right, it was that bolded "400'" climb that clearly is what hes pointing at - as the ice caused the drop, then the pilot sharply climbed, then ice-stall, causes plane to yaw pilot corrects the wrong direction causing spin - all in the course of what seems like ~30 seconds?"

Is what my thoughts are.

Its early to make assumptions, but the weather report confirms the theory, and at the plane previous flight, from the inverse route, a passenger filmed ice at the wings.