Fatal Accident 7-12-23 Beech Debonair (USA)

[rgmwa]

This fatal accident occurred a couple of weeks ago, but should never have happened had the 400 hour pilot had a better understanding of both her aircraft and her own skills. 

Juan gives a good explanation of the likely causes.

 

 

[KRviator]

Seems remarkably similar to the 172 out of Melbourne a few years back that flew into a hill.

From the ATSB: 

Quote

 It is likely that the pilot manually manipulated the controls while the autopilot was on and engaged in a vertical mode. As a consequence, the autopilot re-trimmed the aircraft against pilot inputs, inducing a nose-down mistrim situation, which led to a rapid descent.

[Thruster88]

It reminds me of the two 737 max crashes.  

Edited December 21, 2023 by Thruster88

[KRviator]

Those Max accidents had nowt to do with the autopilot though.

Fighting the trim, yes, but not a mistrimmed (due to the AP) aircraft. The trim movements in the Max was a part of the flight control software to provide an increasing stick force gradient at increasing AOA - which is a certification requirement. In the Max, due to the positioning and size of the donk's, they couldn't achieve that aerodynamically, so decided to use the trim to bias the stick force, based on the single AoA sensor, with the result of it providing erroneous info, generated the "shit, we're approaching a stall" signal to the FCC, which trimmed down to increase the force to hold the nose up, thus simulating the certification requirement. 

Which is great if you're actually approaching a stall. Not so much if everything's normal bar the AoA data...

From an RPT point of view, the closest that comes to mind is that Aeroflot A310 crash where the Captain's son managed to apply enough force to change from LNAV to CWS in roll eventually losing control of the aircraft while they tried to work out what the plane was doing.