If you’re a new student pilot or a flight instructor, then you know the FAA changed the PTS (Practical Test Standards) for Private and Commercial Pilots to the ACS (Airmen Certification Standards). This is equivalent to the bureaucratic reorganizations that routinely reoccur and propel every Federal agency forward, especially when a new administrator takes the reigns, for the purpose of “streamlining” operations and putting someone’s new footprint out there, usually without accomplishing any long-term change that anyone can remember. I’ve paid attention to it but haven’t worried about it too much as a Light Sport instructor, though I am now hearing they’re about to do the same thing to Light Sport, making me sit up and take notice. If you know anything about what was changed, then you know that the slow flight and stall recovery parts of the test standard were “renovated” in an effort to reduce Loss of Control accident statistics, the thing that has been the big push in general aviation for the past few years. If you’re a follower of Rod Machado, then you probably have seen his tweets about how he disagrees with those changes. You can read his arguments against it in this blog: “The Stall Horn Fallacy of Stall Prevention.” Frankly, I agree with him, not only because of the arguments he makes about the learning and training processes but also because I have serious doubts that, from a safety standpoint, it’s a push in the correct direction. I come at this subject as a pilot who’s been around for a while (and interested in aviation safety for quite some time) and as a Light Sport instructor and a manned spaceflight safety analyst. As you’ll see, when I use a space shuttle based safety analysis on this subject, it casts doubt on the whole approach. (Some of will reinforce the arguments Rod was making.)
I personally believe a pilot needs to be able to handle an aircraft in any attitude and that “you fly like you train”. I’ve always taken pride in my ability to handle an airplane in slow flight and right through the stall, something that has given me a better understanding of airplane control in these regimes; I believe in preparing for the “bad day”. So, when you tell me that I’m supposed to only train pilots how to stay out of stalls and NOT how to recover from them if they get into one, it makes me squeamish. It’s like asking me to stick my head in the sand and telling me to take my students with me. It’s not that I don’t understand why the new approach is the way it is; I believe it is tied to the new aircraft certification standards re-write. Part of it is based on the rationale that stall/spin accidents that kill pilots occur too low for any recovery to take place, so it’s a waste of effort to try. (Kinda like “that person has no heartbeat, so just forget CPR and call the undertaker”.) Putting more effort into teaching pilots stall avoidance is always a good thing to do, but the argument that not teaching stall recovery is the way to get there because it “desensitizes” pilots to stall warning systems is not the way to do it (nor do I believe that desensitization is the main issue; how many hours have you spent “disregarding the stall horn? Should full throttle ALWAYS be the response to a stall horn going off? What about on those days gusty days when you’re on the approach and it’s burping at you? Is that a built-in form of desensitization?) The new aircraft certification standards DO put more emphasis on designing in stall warning and resistance systems and also DO mesh better with the new ACS stall response training; but that does nothing for the rest of the fleet that doesn’t share those design features and probably won’t be in widespread use for a decade. Most of the current fleet was designed under Part 23.207 (B) that says: “The stall warning may be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under the expected conditions of flight.” So, there is no requirement that says a stall warning horn has to be included. (I suspect current ASTM standards for Light Sport also follow this approach because my Flight Design CTSW does not have a stall horn or a light…)
So, now, let me educate you a bit on how I’d look at this issue as a space shuttle safety guy.
When looking at how to eliminate or control hazards (and the hazard we are talking about here is loss of control in the form of a stall/spin), the shuttle program invoked a philosophy known as the “hazard reduction precedence sequence”. The sequence consisted of the following approaches:
1. Design for Minimum Hazard – Eliminate the hazard by design where possible. (In our case, make the airplane where it won’t stall or is extremely hard to.)
2. Safety Devices – Reduce known hazards which cannot be eliminated by use of safety devices as part of the system, subsystem, or equipment. (Stick shakers and ballistic recovery systems are examples of this one.)
3. Warning Devices – Employ devices that provide timely detection of the condition and the generation of a warning signal. (Stall horn, audible warnings, lights or other indicators…including angle of attack indicators…fit this category.)
4. Special Procedures – Used when the above approaches do not reduce the magnitude of the existing or potential hazards. (Pilot response to a stall or stall warning fall into this category.)
This list proceeds from the point of the strongest control of the hazard (1) to the weakest (4). For the case we’re talking about, a pilot responding to a stall horn with power or angle of attack reduction will be using 3 and 4. These are the weakest of the controls, i.e., hold the least amount of risk reduction. That said, the reality of a lot of general aviation flying is that we depend heavily on pilot training to reduce risk because of the nature of our aircraft, i.e., low weight and sophistication. That said, the rate of loss of control accidents over the last several decades has remained relatively constant; and since we are primarily dealing with it via the weakest of controls, there is little reason to suspect that training (once we are in the scenario) will have little impact on the rate. I also suspect that there are very often other causal factors (i.e., distraction due to aircraft or operational issues) involved in getting into the “bad day” that any training approach will not address, other than the big one involving “flying the airplane first” and taking the rest of the chips where they fall. I have no knowledge of whether this was considered when looking at the LOC accident rates; I suspect they all stopped at the “pilot eror” point without the substantive digging necessary (if it can be accomplished at all) to nail down the true “root causes”, which often lie deeper than people can or choose to look.
While we’re talking about this, I want to pull on one other analogy from a shuttle safety approach, i.e, the idea of system criticality and how this new training approach affects it. Shuttle had three classes of systems’ criticality. They were:
Crit 1 – systems that if they failed could cause loss of crew or vehicle
Crit 2 – systems that if they failed could cause loss of mission
Crit 3 – systems that, while desirable, would not cause either loss of mission or loss of crew or vehicle.
So, let’s apply this to a general aviation aircraft in this scenario.
Our current approach to the criticality of a stall warning system (because there’s no requirement that a pilot to respond to it and because there its operation is not required for VFR flight) would make it a Crit 3 item. The main responsibility lies with the pilot to recognize his aircraft is approaching a stalled condition and respond accordingly if it gets into it, whether the stall horn is working or not. The new focus on stall avoidance and making the pilot’s response DEPENDENT on the activation of the warning device would RAISE the criticality of the stall warning system if it was assigned one. Since the pilot’s reactions are based on the stall horn (or other warning system) and the ACS committee considered this an emergency, the criticality of the system (if I were rating it) would jump to Crit 1! You don’t fly without a Crit 1 system being operable! Since there are no FAR’s in place that require a stall warning device to be operable. This suggests a disconnect between the training approach which assumes the device will be in place and operable and the aircraft’s required systems. There is much better integration with the new design standards; but for now, this approach is very premature, even if I were not against it for other reasons.