Flanders Peak, Hyalite

This morning I was ascending Flanders Peak via the southeast trees. At approximately 10:30AM, 9500 feet elevation, we dug a pit (photo attached) and was surprised to get a ECTN. However, we did make notes of a buried solar crust between 51-60cm (1F) and a basal crust (P) on the first 5cm of the pit with the same large, sugary facets we've seen all over the Bozeman area sandwiched in between these two layers that supported our plan to stick to low angle slopes. At approximately 1:30PM, on our second lap of the south-southeast bowl of Flanders Peak, I was skinning behind my friend who was putting in a new ascent track when we both heard a large "whump" and a 15 foot crack shot out from under his skis. I also witnessed him drop several inches from the large collapse in the snow. We were on a very low angle slope (less than 25 degrees) at approximately 9700 feet, in wide open trees right at the edge of tree-line and the alpine. We noticed no other signs of instability in the bowl we skied, or on the wind-loaded ridge. We decided to not keep lapping the bowl after this happened but instead skied back to the car.