Garmin ESP system, and instructor awareness
 

Having posted about stalls, and linking an NTSB report, it occurs to me to highlight the other aspect of that report which deserves some sober thinking - the affect of the Garmin ESP system on the pilot's handling during intentional stalls. The report I mention (and contributed to) is reproduced in part here:

https://www.accidents.app/summaries/...20221118106317

Prior to being asked by the NTSB Investigator to comment this investigation report, I was unaware of the existence of the Garmin ESP system (it's new, I generally fly legacy airplanes). So, I had to do some research and thinking to consider how I, as an old pilot, would handle such a new system, as probably the "old" accident pilot had to - unknowingly, I suspect. After sending my comments off to the NTSB, and filing a mental note about new avionics systems, life went on. A month later, life included test flying a Cessna 182P amphibian. During stall testing, sure enough, the airplane begins to "take over" un announced, including a dramatic pitch down, when the pitch trim rolled from full nose up, to full nose down in 5 seconds (normal electric trim operation would have been 15 seconds). Rather startled, I recovered the resulting pitch over (amphibians do not build up speed near as quickly as "clean" planes, so not a serious outcome, but a serious event in my estimation. With no placarding, nor warning, while flying a type I've been flying for more than 40 years, something new happened - control was "supplemented" away from me by a system I did not know was there.

I recalled the comments I had made about the Garmin ESP system in the Caravan. This airplane had a new suit of Garmin glass. Then I remembered the ESP green 45 degree roll indicators, and this airplane displayed those. I wrestled the airplane through roll, and sure enough, the ESP system was activating, and supplementing my control inputs. This sent me back the manuals, and a much better research into this system - and how to turn it off (recommended for flying intentional stalls). There are other concerns beyond the scope of this discussion, including a less than safe possible situation resulting from the combined ESP system, and the MT reversing propeller installed. That's a whole other discussion.

In the mean time, I'm posting this here, for the simple purpose of reminding instructors and check pilots that a new, or retrofitted legacy airplane, could have this system installed. In "normal" flying, I would support this system, as being a "JFK Jr. saver", so a good thing. But, it needs to be properly understood by the pilot, and during training, disabled (a few menu pages in). I have made a safety recommendation that at the very least, such systems must be placarded as being installed and operating in the background. I also have recommended that any airplane with this system be required to have white marks on the pitch trim wheel, which would make uncommanded motion of the pitch trim wheel more apparent to the pilot.

So, if you're training a pilot in a glass cockpit plane new to you, it would be wise to determine the possible presence of the system. The pilot in the referenced accident report did not do this, though in many other aspects, I know that the pilot prepared very professionally for the flight test - in an airplane new to him. The ESP system supplementing his handling efforts during the recovery from an intentional stall made recovery less confident (read the report summary, and draw your own conclusion about that). Then train your candidate pilot to be more aware of the operation, particularly in the background, of systems in the airplane they are flying. The Flight Manual Supplement will describe this system, but it's not in the first few pages - and not placarded!

A simple way to override the ESP is to hold either of the CWS (control wheel steering) or the Autopilot Off button on the control column.

Agreed. But, if you are unaware that the system is in operation, doing so might be a delayed secondary pilot action. During my second test flight stall, I figured this out for myself, and did exactly that as I was recovering the stall. The problem for me at the moment was that I had entered the power off stall deliberately with full nose up trim. ESP rolled it to full nose down, which action I then terminated by holding the CWS switch. that left me recovering the stall with full nose down trim, which I had to hand roll off during the stall recovery. It worked, it was just really messy. Close to the ground would have been scary.

I don't object to the ESP system, my greater concern would be pilots flying a so equipped airplane without knowing it's there at all (as I did, and the fatal Caravan crew may have done), and them not entirely understanding it's ins and outs. The more advanced automation requires more pilot knowledge. I note with some concern that the total number of pages for the pilot information for these Garmin systems in the 182 exceeds the total number of pages in the ground school texts. If a new pilot just got through ground school, and is put into a so equipped airplane, are they likely to devote the proper learning to such a complex system? Instructors will have to mentor this - as long as they understand, and know how the airplane is equipped!

The Garmin system in the aircraft I have recently checked out in has a reference manual of 480 pages, I kid you not. Also…for early basic training I am uncomfortable outside controlled airspace pressing buttons at the expense of looking out of the window…

I ensured ESP was disabled on my experimental after experiencing an AP nose down hardover caused by a malfunctioning ADAHRS (GSU 25C). I believed the system was more likely to try to kill me than to prevent me from killing myself.

About a year later Garmin quietly introduced a modified GSU 25C.

Yes EXDAC, I have been testing a not unrelated failure mode. The airplane I "found" to have the ESP system also has an MT electric reversing propeller. That propeller has an airspeed pilot line diaphragm switch to disable the reverse system at flight speeds. That same switch on my airplane ('same reversing prop) had a hole form in the diaphragm, which caused about a 40 MPH too low airspeed indication. ('took me a bit to trouble shoot that!). So I had a valve put in the pitot line of the airplane I have been testing, which I can open in flight to bleed down pitot pressure, simulating the same failure, and resulting IAS error. Sure enough, open the valve as though I've have a pitot leak and the airplane pitches down considerably. Garmin told me it wouldn't, but it does.

So I have some issues to resolve before I'll issue an STC for this combination of mods to the airplane - and those were not what I was sent to flight test for, I found this by happenstance. The point is to know what you're flying, and what systems are installed. I have also recommended that airplanes equipped with background autoflight systems be placarded as such. Ultimately, an instructor could be asked to do an insurance check flight for a new owner of such an [equipped] airplane - best that instructor be on the top of their game, to prevent a check ride surprise, and to assure that the new pilot gets the whole training for the systems on that plane! This system was not installed in the original 1977 version of this airplane, so I was not expecting it to be there - my bad, lesson learned!