The nose down would probably have been caused by a panic stall trying to reduce the vertical impact with the ground. As you said the aircraft doesnt know its in moving air and will behave the same Ie STALL.
Forget triangulation for a moment.
You are in a speed boat travelling at 10 kts against a 15kt current ie 5kts against the riverbank.
Turn around and you will be travelling at 25kts against the river bank which way would you rather be going when you hit the river bank
Now cut across the current at 45 degrees and drive down river into the bank.
Do you still think your collision speed with the bank will be 25kts?? going 45 degrees??? across
Why 15kts? if you take a mass of air which is moving at 15 kts funnel it into a spout will the air accelerate through the spout or remain at 15 kts? Mountain shapes can do the same.
I fly into an airfield surrounded by hills!On approach I always avoid a certain point even in light winds as there is always turbulence at that point.
On a stronger wind day I forgot went through that point lifted out of my seat and put a 2 inch cut in the top of my head.
Everywhere else that day the wind was infact 15 kts but not at that point WHY???
Pace