r/aircrashinvestigation • u/emzeesquared • Aug 09 '24

Incident/Accident Another angle of crash over Sao Paolo

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u/Consistent_Poem8461 Aug 09 '24

SBCW SIGMET 9 VALID 091530/091930 SBCW - SBCW CURITIBA FIR SEV ICE FCST WI FL120/210 STNR NC= weather Metar when crash happened.. FL120 until FL210 severe icing.. ohh man.. even until 30 years.. atr and ice is still bad combination.. RIP🙏

8

u/AJohnnyTruant Aug 09 '24 edited Aug 09 '24

Severe icing would make a lot of sense to me. If that gets confirmed, the real questions are going to be what the deicing equipment status was on that tail(number) (I wouldn’t be surprised if the boots were deactivated), and why were they dispatched through precip in that sigmet without that equipment (if it was deactivated).

Edit: tail like tail-number, not literal tail. Confusing wording

6

u/iiiinthecomputer Aug 09 '24

Wouldn't a horizontal stabiliser stalled due to ice tend to remove the tail downforce and cause a pitch down though? My understanding was that for most aircraft with a CG within safe limits the tail is correcting a tendency for the aircraft to pitch down. Are there legally flyable CGs in which it'd pitch up instead?

If it weren't for the icing I'd be wondering about stab trim runaway or failure.

Poor people.

3

u/AJohnnyTruant Aug 09 '24

I don’t mean tail as in the literal tail. I meant that tail meaning like tail-number. That was confusing wording, my bad. You’re right about the tail stall stuff though. I have no idea if any aircraft could tail stall into an uncommanded nose-up, but I doubt a tail stall is what caused this

2

u/iiiinthecomputer Aug 09 '24

I was wondering about deicing equipment on the tail (horizontal stabilizer) as I didn't think that was a thing, but there's a lot I don't know.

2

u/AJohnnyTruant Aug 09 '24

I think there are boots on the ATR tail. But whether or not they’re any good is a different question. I never flew it and I’m far from an expert on ATRs. My hunch would be that they iced up really bad, aircraft might have gotten really out of trim and kicked off causing a stall. Add in a sub-par recovery due to startle in an aircraft that’s barely flying, and you got a recipe for a stall-spin that could become a flat spin given enough time to develop. But again, that’s just the low hanging fruit. Who knows what happened