Originally Posted by
Lonewolf_50
For Jim Eli: Amen. The transition from VFR scan to IFR scan, if not practiced, can create its own problems.
That's how we taught it ... wait, how many years ago has it been? Yikes, gettin' old!
I am trying to piece together in my head a picture of what was going on during what looks to me like a climbing turn to the left.
If the pilot also slowed down while entering that climbing turn (trading airspeed for altitude, and also creating a tighter turning circle if he knew of rising terrain to his left) he may have -- speculation here -- created for himself an unusual attitude in IMC within a very short time after entering the goo, and, with a three axis change in flying parameters, induced a mild sense of vertigo. (--Guessing here-- and remembering a few of my own cases of The Leans that happened over the years)
Now the pilot is playing catch up. Finally getting instrument scan together, realizing (perhaps) that wings are not level, and begins to recover from unusual attitude/upset, is unable to arrest descent before running out of altitude.
Not sure all if the pieces fit, but that sequence seems to be a way that the end condition that the mountain bikers heard/saw could come about.
I think you've got it about right, Lonewolf. Like many others here, I have also experienced the extreme difficulty of unexpectedly transitioning from visual flying to instrument scan. When you add in rapid attitude changes in multiple axes, it is VERY easy to get the leans and then it is a lot of hard work to overcome that.