Stalls in the Pattern

[PA11]

I'll save the speculation for later, but I wanted to comment on all the ASI failure / AOA crutch commotion. Can we not fly airplanes without airspeed indicators?

If we have a reference for pitch in the pattern and on final, and a general power setting that holds a desired airspeed in the varied configurations and stages of the pattern, can't we negate having to look inside and just fly the airplane?

Even at merely 10 hours, students have demonstrated mastery of aircraft control without having to look at an ASI, let alone an AOA. Perhaps the next few tries around the patch, bring a safety pilot or CFI with you and try a few circuits without the ASI.

[steveinindy]

Just asking. I was told in the class room that whoever's cadaver had the highest CO2 level was likely the one on the controls at the time of impact. The FAA guys in the room agreed. Could this be another urban legend? The bone injuries were also covered as indicators.

Bob

Again it is one of those things that the field came to treat as true without any evidence to back it up. CO2 levels will increase postmortem and a short burst of exertion immediately prior to impact is unlikely to create a significant elevation. As for the fractures, that was part of what I mentioned in the earlier post.

[Ron Blum]

Sorry, I had to go on vacation :o) The accident was a stall-spin; how the pilot arrived there is irrelevant. I agree with everyone that you should be able to fly the airplane without an airspeed indicator (in a safe, reduced envelope). Although I am an engineer with 25+ years of Flight Test experience, I am not good enough to calculate stall speed real-time as I'm yanking and banking. I also agree that an AOA indicator on the panel is useless in VFR flight. That is why bigger, certificated airplanes have stick shakers and/or pushers. Yes, airplanes like Cubs give plenty of stall warning, but as we try to get more and more out of our designs, stall warning typically is reduced. For those that think that they haven't ever flown AOA, they have never flown a Piper, Beech or Cessna because that little horn you hear (or light in some Pipers ... which is not currently legal per the regulations) is AOA based. What I am suggesting is some kind of tactile stall warning in all airplanes ... including experimentals. It is coming; ask ASTM, GAMA, AOPA, FAA, etc.

I am not sure what the S-6 has in it for stall warning; it is probably up to the builder/owner. Randy makes good airplanes.

[Ron Blum]

I am not sure what the S-6 has in it for stall warning; it is probably up to the builder/owner.

Update: The S-6 owner that I know says that there was not a stall warning device on his airplane, and he didn't think that a stall warning device was an option. He also noted that the airplane has good control up through the stall and releasing back pressure recovered the airplane.

[Bill Berson]

Update: The S-6 owner that I know says that there was not a stall warning device on his airplane, and he didn't think that a stall warning device was an option. He also noted that the airplane has good control up through the stall and releasing back pressure recovered the airplane.

It helps to specify stalls behavior at different power levels. Most planes have gentle power off stalls. But try a full power go around stall. Most pilots have little exposure to this. ( do it above 4000 agl, and be prepared for a spin recovery)

[Ron Blum]

Agree with you, Bill. Some airplanes will also stall well at a 1knot/sec deceleration rate (or higher) and flip on their back at <0.5 knot/sec rate. So many factors.

[David Pavlich]

About the best analysis of a stall/spin I've read is in the latest issue of Flight Training titled "The Not-So-Obvious cause of stall/spin accidents" by Budd Davisson. I've read a lot and viewed a few DVDs and all that I've read (training stuff mostly) discuss the classic stall as is taught in flight school. This article goes beyond that and does give this non-pilot a much better perspective when reading the NTSB accident reports.

David

[martymayes]

What I am suggesting is some kind of tactile stall warning in all airplanes ... including experimentals. It is coming; ask ASTM, GAMA, AOPA, FAA, etc.

Ron, what's your source for forecasting tactile stall warnings are forthcoming for GA lightplanes? Is it being discussed in a steering comitttee or something?

Personally, I don't see it happening anytime soon, x3 for experimentals. I think the 9L-3704 crash in Buffalo has made it clear even sophisticated stall warning systems are not 100% idiot proof. The real solution is training but I know that's a dirty word in many aviation circles.

[Ron Blum]

I am on the ASTM F44 Committee that is in the process of putting current part 23 into ASTM standards (similar to LSA). There are several stages of how the work is going to progress, but eventually the compliance will all be within ASTM standards. The FAA, foreign Agencies, OEMs and users are very involved in this process (unlike LSA) to get common guidance throughout the world. Anyhow, on the first day of the first face-to-face meetings the entire group was briefed on why this process was being done (1/2 cost to certify and 1/2 accident rates). The #1 item on the safety list was stall/spin or what the group has titled "Loss of Control". For the aerobatic person on this thread, I didn't choose those words as I think that Shawn Tucker and the likes would be offended if people referred to him being out of control for 1/2 of his routine (loss of control means something else in the flight test world, too). AOA was discussed as the silver bullet solution to the stall-spin problem. You're correct in that you can't make anything idiot proof ... we'll just make better idiots. The AF447 stall is a great example of the highest technology not saving the airplane and all the people on-board. Personally, I think that if we continue to make systems smarter and smarter, we, as a people, will get dumber and dumber.

[steveinindy]

I think the 9L-3704 crash in Buffalo has made it clear even sophisticated stall warning systems are not 100% idiot proof.

I think that crew catches a lot more **** than they should honestly. They were in the mindset of icing (references to transcripts about "the worst icing they had ever seen" etc) and in an aircraft where it is drilled into your head (thanks to the Comair crash on approach to Detroit Metro) that tailplane icing stall is a major concern. The onset of that is an abrupt and unexpected pitchdown possibly proceeded by control vibrations and a change in configuration. The upset came after they extended the flaps. The response they gave (flaps up and stick back) is exactly what you would expect if someone were responding to the tailplane stall. The unfortunate thing is that they were too low to have time to figure the problem out. I am not excusing their culpability in causing the crash. I am simply pointing out that instead of painting them as a pair of clueless stupid idiots who didn't deserve their licenses, let's look at the bigger problems here and find real solutions to them. The problem of "tunnel vision", confirmation bias and attention blindness needs to be looked at here unless we wish to see this same issue come up again. Maybe not in this same exact scenario for the implications are much broader than a lot of us are comfortable admitting.

Were they not paying attention to airspeed? Yeah but then again you try working that schedule and see how attentive you are. Did they misidentify things? Yeah but welcome to how the human brain works. All too often you see what you want to see. It's easier to look at this as "stupid pilots" than to look into the system that produced the accident. It's the same thing that happens when you have a midair on a clear day. You get "the pilots failed to maintain adequate lookout" or "how stupid is that!?" versus question whether or not "see and avoid" has some glaring shortcomings that the average VFR pilot is either not aware or chooses to ignore because of hubris or whatever else you want to chalk it up to. Either we are rank amateurs or we are professionals and are willing to ask and be asked the hard questions. As Gene Krantz put it in the aftermath of Apollo 1, being "tough and competent" is the price of admission to places where the lives of others are in your hands.

I'll put away my soapbox now.....