This is an excerpt from a report made to the Aviation Safety Reporting System. The narrative is written by the pilot, rather than FAA or NTSB officials. To maintain anonymity, many details, such as aircraft model or airport, are often scrubbed from the reports.
On short final to a visual landing, the autopilot (which was turned off) pushed the nose towards the ground. I was surprised. I pushed and held the autopilot disconnect, recovered, and landed.
I was familiar with the ESP (Electronic Stability & Protection) feature on my recently installed Garmin GFC 500 autopilot in theory, but seeing it in practice was scary.
Landing speeds for my Bonanza 33 are 64 to 70 knots depending on weight per the POH. I was light, winds were light, and I intended on landing at 68 knots. The GFC 500 ESP pushes the nose down below 70 knots.
Note that a V Tail bonanza with the exact same flight characteristics has a GFC 500 ESP speed of 65 knots, which is better.
This is a hazard that needs a software modification to correct.
Primary Problem: Aircraft
ACN: 1873529
I have now had this happen twice to my Vans RV 12 with Dual Garmin g3x.
I had a very similar experience, also in a Bonanza with a GFC500. The avionics had been recently installed, and I had only a few hours flying it. I had read the book, and knew about ESP and the fact that it’s always lurking, even with the autopilot disengaged. That level of knowledge didn’t help at all during the event. ESP aggressively pushed the nose down on final approach although the speed was entirely safe for the aircraft weight and configuration, and it was surprising how much force was required to overcome it. I didn’t think about disconnecting the autopilot, because it already was… It’s the only time my wife has ever been scared in an airplane. I’ll note that with my system, which has a G3X, the ESP engagement parameters can be changed in the G3X setup mode.
Folks… when you install new technology in an old bird ya better Fully understand the systems. Too many jump on the bandwagon of being ignorant and blaming the system design. The ESP is a good design and one must fully understand it if installed.
Wow, sounds like the 737 TCAS issue. That would be scary, you think when something is turned off, it is disabled.
Exactly what I thought when I first read this. I just didn’t want to be the first to say it.
I have never heard that the 737 had any issues with the “TCAS” system, which is for traffic avoidance.
Too many TLAs in this industry.
Sorry, meant MCAS.
I have a plastic zip tie around the circuit breaker for my autopilot in order to make it very easy to identify the autopilot circuit breaker: for positive disabling if there is interference in flight controls. No trouble shooting needed.
Autopilot has both electric and auto-trim plus Yaw damper.