I don't often intentionally trim a Cirrus right wing and nose low and then let go of the controls. But last week I did just that. I did it a few times, in fact, and every one of those times things began to happen in a hurry. The ground directly below the airplane quickly came into view as I watched the heading start to spin, the airspeed build and the altitude tape sink. And bear in mind that this all happened within seconds of my letting go of the yoke. It was, as you've probably figured out by now, the beginning of the classic graveyard spiral.
Only in this case nothing bad happened. In a couple of instances I simply let the system stop the spiral from developing, eventually returning the airplane, without any input from me, to controlled flight. In another I simply pushed a small button on the panel and watched it recover with no additional input from me. In each case the airplane I was flying was able to recover from what surely would have been a catastrophic loss of control with, at most, a single button push.
I should point out that my intentionally poor flying took place in two Cirrus SR22 airplanes in two states on two different days, and I walked away — well, flew away — from both encounters with both me and the airplane none the worse for wear, all thanks to new envelope protection systems developed independently by two avionics manufacturers, Avidyne and Garmin. Potentially the systems, and others that will likely follow from the companies, will be installed in hundreds of aircraft models.
The goal of both systems is the same: to eliminate as many loss-of-control accidents as is technologically possible while still keeping the experience of flying the airplane largely the same for the pilot. This is done by employing flight control system inputs (more on the specifics later) to keep the pilot from unintentionally upsetting the aircraft, such as I intentionally did over and over again.
At AirVenture Cirrus announced its plans to certify Garmin's system, known as ESP for Electronic Stability and Protection, on its four-seat SR22 single, most likely by the time you read this. Avidyne's system, known as Envelope Protection, is already flying in more than 200 airplanes equipped with the company's retrofit digital autopilot, the DFC90. Garmin is also certifying its ESP system for the G1000 retrofit flat-panel system in the Beech King Air B200.
Garmin Adds Two Kinds of Envelope Protection
Garmin's ESP operates in the background all the time when the autopilot is turned off. It doesn't technically use the autopilot but instead makes use of the servos to add force to the system to make the airplane fly with a feel of greater inherent stability.
The system is available for new Cirrus SR22s as a free standard feature and as a retrofit for existing Garmin G1000-equipped King Air B200s for a charge of $17,000.
While ESP is an always-on utility, Garmin is also offering envelope protection in autopilot mode for selected models as part of its GFC700 autopilot system. Though they are talked about as different systems, ESP and autopilot protection are not completely separate. In certain instances when the system determines that the pilot is not responsive, ESP will hand over control of the airplane to the autopilot, so the systems are in some cases linked. Moreover, it's likely that every airplane equipped with the always-on ESP system will have a list of autopilot envelope protection features that will be part of the system too, providing envelope protection in nearly every phase of flight.