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The weather has been very unsettling here in the last couple weeks. I'm sorry for your loss @robin ardoin. Local (Nashville) news is doing less than stellar reporting including the "Fork Tailed Doctor Killer" spread with some A&P/IA voicing his "opinion" to an uneducated anchor.
Is this in an online news article or on-camera interview that can be found?
You and I came to two different conclusions re: the accident flight track. To me, the slight zig-zags in the last 25 min look more like small (possibly erratic?) oscillations around his direct course rather than effective weather deviations. The rapid altitude excursion at the end is either a poor choice to try to outclimb the weather or the beginning of the end when he got caught in a strong updraft.
It was right at the boundary of decent and not great. There were fairly light echoes that initiated right as the aircraft arrived in that area. Echo tops were 5k up to 10k, which encompasses the altitude he was at. But I don’t see it so much as an issue of severity, but more to do with a VMC to IMC transition. The airplane didn’t break up in level flight, it went into a 26,000 fpm (>250 knots in the vertical) spiral, then broke up.
Could that be the problem? Maybe he left it on AP and it over-stressed to the point of failure? (Pure conjecture from a newbie, hoping to learn something from responses).
This is a good point, the several-hundred mile track from his departure to a point where the first left deviation happened (near Lawrenceburg) was razor-straight. But from that point, the track shows small wobbles that seem to indicate it was being hand flown at least part of the time.
Ok, maybe I wasn't clear...I don't think weather was so severe that it (meaning just extreme turbulence by itself) caused a break up...could he have lost control in moderate turbulence while IFR? Yeah, that on the other hand, is very possible...
If you look at the altitude, it also starts very small oscillations about the same time the lateral track started to wobble. I too wonder about an autopilot failure. Add in a climb and vmc-imc transition into a little cell with lots of lift, I could see someone getting behind and losing control.
Hence why I said, "...main factor..."
That's also my purely speculative guess. Or perhaps turned the autopilot off, for some technical reason, to climb from 7k to 9k with the intent to re-engage it, but lost it (spatial disorientation) before that could happen.
I absolutely think that deliberate deactivation of the autopilot is as much a possibility as it being knocked offline or some other defect. Using autopilot in IMC is a well known benefit, but there’s a line drawn when turbulence or icing enter the picture, and it gets fuzzy when it it’s not super obvious (like when those conditions are embedded or encountered at night). How we react to the potentially sudden deactivation and resort to our scan and hand-flying skills, including any possible trim issues, is often a significant factor in the outcome.
Yup....they like to call it the Swiss Cheese model. It doesn't take just one event or link in the chain....but multiple risks factors that are additive till.....
That’s one method. There are actually several, just different variations on the same theme.Yup....they like to call it the Swiss Cheese model.
Just pointing out that a chain of events takes only "one" link to break....vs multiple risk factors.
I recall seeing a Bonanza in a shop, I think at N Perry in Hollywood, FL. It had allegedly encountered some light turbulence while inbound.
They are not falling out of the sky....the accident rate will bear that out. This guy obviously was into some nasty turbulence....it was more than just light. IMHO.
