Oklahoma Crash  

That seems way off.

If you google earth that crash area and see eye view the elevation shows 1,565ft.

https://earth.google.com/web/@35.55070981,-98.54566407,476.37454527a,6178.26056539d,35y,359.60221527h,0t,0r/data=OgMKATA

Now we all know the flightaware mode c data is shown at 29.92.  So if it fell off of the map at 1700ft reported alt on a 30.44 baro set day, the best he could have been was actual MSL alt of +476.2ft or 2176 ft (msl)

MSL from elevation equals AGL.  2176-1565ft= 611ft. AGL.

U can check the math here.

https://www.weather.gov/epz/wxcalc_pressurealtitude

There was a lowering of pressure going on also to consider.  High to low look out below.

The baro was steadily falling that day and into the next day.

I think rising terrain coupled with a falling baro and a failure to increase alt and hold a cruise alt of only hundreds of feet above ground level may have caused this accident.