Tallac-Human triggered slab avalanche in corkscrew bowl

Disclosure: I am not a professional or a forecaster

This was a very eye opening experience on a number of levels.  Here are a few thoughts and pitfalls that our team discussed when we debriefed following the event.  This slide was not giant but could very well have buried a human, was very heavy with large debris, and ran for quite a ways  through some trees thereby increasing the chance of full burial and blunt trauma.  So real deal stuff.

First, this is widely considered a safe zone by Tahoe locals.  The entry off the ridge certainly has steep entries, and cornices and wind slabs, but there are several "safe entries" into this bowl and this was one of them. Although it was about 35 degrees for a short time and fairly open.  So, good reminder.

We knew the set-up, the reports have demonstrated the weak layers, and we gathered our own pit data prior to reaching the ridge which clearly showed reactive wind slab on a hoar layer about 30 cm deep (CT3 for me).  We initially decided to drop in below the ridge because of this data, and for reasons that aren't clear, we went ahead up to the ridge, as it was very close and not much steeper.  

We skied our first lap on skiers right of the bowl with no evidence of weakness, whumfing, or cracks or slabs off the ridge right there.  

We opted to ski a second lap off the ridge skiers left, which has a fairly low angle entry available in spite of the majority of it being quite steep, we thought we could safely enter the bowl here,

There was already a set of tracks right through the line we chose to ski.  CLASSIC false security pitfall.

The first two skiers dropped in with no problems, although the second skier saw a small shooting crack at the entry point. The slide was triggered by the third who picked a line in between the two other tracks.  Very unusual for this third person to be the trigger.  I am unable to comment on any visible potential trigger points as I didn't visualize this area. I was below and did not drop in at that point. 

It was apparent to me that the person who triggered the slide was above, and this is a scary situation because it takes a long time to skin up.  

We immediately began a search as two of our party were not immediately accounted for. One skier went down the avalanche path, and I immediately started going up it.  Within a few minutes, we all had voice and visual conformation of each other.  The snowboarder partially buried above just needed a little help getting out of his bindings and digging out one of his lower extremities.

Take home:
-Stay away form the ridge lines on days like this especially with known buried hoar
-Use the data you have to make a plan.  In this case we realized we should avoid the ridge, and assumed our primary risk was wind slabs off the ridge, but went up anyway.  We initially decided to drop in low below the ridge and subconsciously changed out minds without even realizing it.  This is a cognitive error.  Make a decision, verbalize it, discuss it, and then do not change unless swayed by additional data.
-Be very very careful when are there buried hoar layers and wind.  Zones traditionally considered safe may not represent safe zones in these conditions.