Hawker 900 down in Utah
 

From Denver Post, 8/2/2024:
", a Hawker 900XP charter plane, took off from Grand Junction at 10:37 a.m. and crashed just ten minutes later on the Utah side of the border, according to flight tracking site ADS-B Exchange.The plane was headed for Tacoma, Washington, according to Utah’s Grand County Sheriff’s Office in a news release."

Deputies confirmed a pilot and second in command were on the plane. The release said notification of the next of kin would come before their identities were released. A post about the crash on the Aviation Safety Network website stated the two occupants of the plane were dead.

https://aviation-safety.net/wikibase/351542 Further details as provided.

That is going to be an interesting report. Was there any convective weather or severe mountain waves/CAT around? The Hawker is a pretty strong plane, and its is also fairly benign handling, and has the stick pusher/ident system. aerodynamically, the plane doesn't have particularly untidy manners. At 20,000' they have buckets of excess trust, even with one only going. Curious.

The data shows a climb to 20,000 feet then level flight. Initial high speed cruise but then a gradual and steady speed reduction in level flight until a possible stall and high speed descent

Word 'on the street' from other forums suggests a post-TKS maintenance stall test.

Stall test after maintenance. You can guarantee this test was going to end in tears one day.

For a C of A renewal a stall test used to be called IMMSMC and it was removed by most authorities. One of my past employers decided to do such a test flight as accepting a used classic B747 type into their service; the post flight report was a scary incident in which the recovery also involved overspeed of N1 on at least two engines.
Surprised there is a procedure for this high tail model 900XP.

Stall testing on DC-9 Super 80 (fuselage 909) came very close to needing spin chute deployment. Why would testing after wing maintenance require testing past sick pusher alpha or even beyond shaker?

The video posted above suggests that the Hawker's handling in a stall condition is anything but benign.

Dearth of new information.

NTSB Aviation Investigation Preliminary Report - N900VA

So no breakup during flight or loss of any major structural parts. A corkscrew path sounds suspiciously like a spinning airframe. The instructions for a stall test state 'not above 18,000 ft' but they started at 20,000 amsl. Those 2000 ft should not create a major problem all of a sudden, but the meteorological conditions could have led to a higher true altitude. Just guessing here as I cannot remember the formulas right now...

The ADS-B data I looked at shows GS 387 mph at 15,000 ft. That is not consistent with a sustained spin and neither is the flight path. Hopefully the FDR will have far higher data resolution and will show the dynamics of the attempted stall recovery.

edit to add image derived from low resolution ADS-B data:

https://cimg6.ibsrv.net/gimg/pprune....33a80e9b84.png

Spin or spiral dive?

A spin is characterized by high descent rate and little or no lateral position change. I see at least three separate spin events in the previously posted 3D image.