What we need to consider is that our perception of the cause of the accident depends on the dangers we have identified, and that depends on the information we have, and our background.
Discussion is focused on the weather conditions, or rather speculation about them; the NTSB have asked for and apparently received photographs from the public, so we'll likely learn facts as the preliminary report comes out. For the record, KVNY is at 800ft and reported an overcast cloud deck at 1300 ft AGL at 9:51, which would make the ceiling ~2100 ft MSL; from 9:45:11 to 9:45:21, N72EX was at 2100-2115 ft altitude as per its ADS-B transmissions as the highest level of its flight path. SoCal TRACON also heard the pilot announce that he was climbing to avoid a cloud layer, and we know that people on the ground reported foggy conditions. So the dangers we think likely are that the pilot might have been in clear air, but lost sight of the fogged-in ground and hills, and thus lost visual reference to a horizon; or that he broke into the cloud deck above inadvertantly. I haven't looked at satellite imagery, so I don't know if there were any holes in that cloud deck that he could have wanted to climb through, but it feels improbable.
But helicopters can crash in any weather. In 1999, Island Express Helicopters crashed N3593S because a loose pneumatic fitting caused the engine to go to flight idle power at a low altitude, which resulted in a forced landing in hilly terrain. The pilot autorotated successfully, and everyone survived. In 2008, Island Express crashed N67GE when its turbine failed unexpectedly (it was properly maintained); the helicopter was low and had to travel to avoid powerlines and buildings, and half of its occupants did not survive the subsequent hard landing. In this case, too, even the cracked fan blades that caused the accident made it to the crash site, because they remained attached. Knowing this, we see the danger that something essential in the 30-year-old helicopter broke, even if it was well maintained.
Or the pilot could've had a medical event, but we have no information on that at all, so it seems very far-fetched simply for that reason.
So it could've been "pilot error", and it makes sense to discuss this scenario because that is what we have the most information on, and also what most affects "lessons learned". But I feel that it's premature to outright dismiss the other scenarios as "too much of a coincidence" when we don't have enough information to judge the odds.
P.S.: Van Nuys also reported 2.5 sm visibility, so a helicopter traveling at 120 kts would be able to look ahead more than a minute of flight time. We don't yet have information on what the visibility was in the hills, at altitude. Looking down through a thin fog layer is easier than being in it, so ground witnesses may not tell the whole story.
Last edited by Musician; 31st Jan 2020 at 10:41.