Well the sheriff reported a debris field 300'X300' so yeah he hit that foothill pretty hard. He also said there was a pretty sizable fire that was put out. I think you can draw some pretty good conclusions by that.

Sounds like he was hovering, then saw the weather getting worse so pilot turned around or so he thought but went right into a mountain.

He said when they were right above him they were going that slow. Probably then accelerated into the side of the mountain.

But why? If you were going slow because you couldn't see, why would you then accelerate to 180+ mph when you still couldn't see? This just doesn't make any sense to me.

And don't they have collision avoidance systems on aircraft for just this sort of thing??

Probably a dumb question but what should the pilot have done once he encountered those conditions?

He was probably hovering circling around trying to get bearings or a visual. A 13 million dollar helicopter most likely had a pretty extensive avionics package probably state of the art navigation. Either it failed or he made a serious blunder and flew off in wrong direction that he thought was right considering how hard he hit that hill.

Just a guess here I am not a pilot but my guess would be get altitude and get above the low ceiling. Then get info on the nearest area not experiencing these conditions and land there.

So I'll let the actual pilots correct me here, but that green line rocketing into the negative figures has to reflect the terrain coming up to meet him, right?

Because the relative altitude stays fairly stead; never drops significantly. Meanwhile his vertical speed notes that he's 'falling' extremely fast over those last 14 seconds. From a virtual 0 vertical speed to a -5000 ft/s in the span of 14 seconds would be just pulling MASSIVE Gs if you were doing it when the ground is stationary. Meanwhile his altitude remained fairly steady...

Well since his height above sea level isn't changing nearly as fast as his vertical acceleration is, wouldn't that seem to suggest that the ground is coming up to meet him instead?

Just seems more and more like the pilot thought he could make a bit of a banked turn to get the hell out of that fog, lost where he was and drove the thing into a mountain at almost full tilt.

As to his speed - I can't say much about how to pilot a helicopter but my guess is that their handling characteristics are much more precise with some velocity behind them. That's just kinda the nature of flight; most aircraft suck at/near stall speeds and when they're actually moving forward, you get the full benefit of what they can do from a handling perspective.

I wonder if he was just trying to get the hell out of that fog in a hurry, was trying to keep his speed so he can do as much as possible to gain altitude and/or handling, and simply lost where he was. It would do a lot to explain why he actually throttled up in the minute leading to the impact.

This is looking more and more like it's damn near 100% pilot error with weather as the primary factor.

I might be misreading the graph, but it's over a span of 40 seconds.

Looks to be in a 1200 fpm (feet per minute) climb for 20 seconds, then descends rapidly (1000-5000 fpm!!!!) which leads to airspeed increase.

Altitude listed is MSL (Mean Sea Level), not AGL (Ground Level), and if we looked at a chart the terrain around the site is probably 1300ish feet above sea level.

4864 feet per MINUTE, not second. Just under 60 mph. Straight down. In a helo that's probably way fast.

Pilot also lost radio contact, and I wonder if that area or the conditions also had an impact there.

They didn't lose radio contact, ATC said they were too low to get it and therefore didn't have contact with Van Nuys ATC for the last :30

He lost 800' of altitude in 10-11 seconds at the end. Holy shit. Controlled decent in a small airplane averages 500 fpm.

Yikes

Yeah he was descending at nearly 60 mph. Hard to believe that was purposeful

Yeah, my brain scrambled there and I was reading the wrong side of the graph. He was clearly descending pretty quickly at the end there.

Now the negative vertical speed makes more sense. The tight scale of the correct axis and short timeline threw me off. Losing 800 feet relative to sea level in 11 seconds is incredibly dramatic.

So now I wonder if maybe there WAS some kind of catastrophic failure on the aircraft. What else would've had him giving up altitude like that when he's clearly looking to find visibility and has already held down low (and knows full well that getting below the cloud deck isn't a realistic possibility).