Angle of attack

[raytoews]

Aircraft Spruce sells three different AOA's.
One uses a probe under the wing, one measures the difference in pressure above and below the wing, the third uses a vane in the airflow to measure angle.
Does any one have experience with them?
ie:
Ease of installation
Ease of setup
How suceptable to damage
Do they allow accurately for flap selection

I assume the accuracy of each is acceptable

Most large a/c use the vane type, is it inherently better?

Ray

[steveinindy]

I have never seen a head to head comparison between the types or different manufacturers. That said, my preference has always leaned towards the vane type because of the idea that if it is good enough for the military or airlines then it's good enough for the slow little airplanes most of us fly.

[rleffler]

Aircraft Spruce sells three different AOA's.
One uses a probe under the wing, one measures the difference in pressure above and below the wing, the third uses a vane in the airflow to measure angle.
Does any one have experience with them?
ie:
Ease of installation
Ease of setup
How suceptable to damage
Do they allow accurately for flap selection

I assume the accuracy of each is acceptable

Most large a/c use the vane type, is it inherently better?

Ray

I only have experience with the AFS AOA unit. Here is a link to a presentation that may provide some additional insight.

http://www.advanced-flight-systems.com/Support/AOAsupport/AOA%20slides.ppt

In my installation, both the EFIS and AOA are aware of the current flap setting.

[Sam Buchanan]

Aircraft Spruce sells three different AOA's.
One uses a probe under the wing, one measures the difference in pressure above and below the wing, the third uses a vane in the airflow to measure angle.
Does any one have experience with them?
ie:
Ease of installation
Ease of setup
How suceptable to damage
Do they allow accurately for flap selection

I assume the accuracy of each is acceptable

Most large a/c use the vane type, is it inherently better?

Ray

I have been flying an LRI angle-of-attack indicator in the RV-6 for ten years. I consider it one of the most important instruments in the panel. You can read my article about my LRI installation here:

http://thervjournal.com/liftreserve.htm (http://home.hiwaay.net/~sbuc/journal/liftreserve.htm)

When the Dynon D-10A was installed in my panel I replumbed the AOA lines to also feed the Dynon AOA indicator via the LRI probe. This works perfectly which retains the mechanical LRI indicator but adds the Dynon audible warning.

I built an LRI for my Legal Eagle and it works great in the low-n-slow corner of the performance envelope, too. The LRI is my primary take-off and landing instrument in both the RV-6 and Legal Eagle XL and is the key to safely achieving high-performance landings.

I highly recommended AOA regardless of which system is used. The vane type system would be my least preferred method since it relies on a mechanical sender, is prone to damage.......and looks ugly. Both the probe and port systems work very nicely.

[iFLYblog]

I really need to get an AOA. I had plans to when I built the airplane, but talked myself out of it. Sam, you make a great argument for it.

[rleffler]

Brent,

The good news is all you need is the AFS AOA wing kit to display on your EFIS. I'm assuming that you have the 3500 and not the 2500. It's a pretty simple mod to install. You can reach everything from the wing tips and all you have to do then is pull the tubing through the wing into the cockpit. The AFS provided tubing is much smaller than the 1/4" tubing used for the pitot.

Some folks do prefer the AOA display mounted on the glareshield, which I think is better too, since you keep you head out of the cockpit during landing. Budget forced me to settle for the one on the EFIS. But then I can always add the glareshield mount display later as budget permits.

bob

[Anymouse]

I had the AFS AOA installed prior to first flight. It's worked flawlessly since then. A few years later I got their EFIS. I opted to keep the original AOA display, rather than pay the extra to have it displayed on the EFIS. I'm glad I did it that way. The display on the EFIS is much smaller and can get lost with all the other info that's being displayed.

JMNSHO

[Bill Greenwood]

This might be a very good product test for AVIATION CONSUMER to do. It would take instalation and therefore a lot more work and expense than many of their others tests.
Maybe one of you guys who know or use A C will suggest/request it from them.

I have long thought about having one of the AOA systems. A story is that Orville Wright said that it should be used after his ride on a big Connie or DC-4 type when he was gettin along in years.

The biggest reason that I have not installed the AOA is having to cut into the wing, and also shortage of panel space for the indicator. I don't have any EFIS in my plane and don't want one, but if I did have an AOA, I would like to have it stand out and not be buried in another display if I was going to be using for a critical moment like landing.

My guess, and nothing much to base this on , is that once you start using an AOA you probably find that is and the airspeed indicator are pretty much in agreement. By that I mean that if you do a short field slow landing and come in on the margin at the bottom of the color arc on the AOA, then you will be at the speed that you would use anyway on the airpseed indicator for such a landing. Thus one comfirms the other.

I think I guess this is true is because most airplanes, not counting some jet, but most normal piston type airplanes have and do use an airpspeed indicator, and have not gone to AOAs. Now maybe that is also becaue the normal airspeed indicator is cheaper than the AOA system, even if not really better.

Obviously we can and have flown for a century or so without having AOAs in most planes an it works ok.

[rleffler]

The biggest reason that I have not installed the AOA is having to cut into the wing, and also shortage of panel space for the indicator. I don't have any EFIS in my plane and don't want one, but if I did have an AOA, I would like to have it stand out and not be buried in another display if I was going to be using for a critical moment like landing.

Bill,

Not all solutions require cutting into the wings and/or panel space.

The AFS AOA only requires a few holes to be drilled into the wing. Two are for mounting screws and the third, which I believe is a 3/64th is for the opening for the AOA. They have a monitor that is about the size of your thumb and can sit on top of your glare shield. 12v to the module installed behind your panel and run the two small tubes out to the wing and you're done. Pretty straight forward to install if you have aluminum wings.

bob

[Anymouse]

My guess, and nothing much to base this on , is that once you start using an AOA you probably find that is and the airspeed indicator are pretty much in agreement. By that I mean that if you do a short field slow landing and come in on the margin at the bottom of the color arc on the AOA, then you will be at the speed that you would use anyway on the airpseed indicator for such a landing. Thus one comfirms the other.

Keep in mind that an AOA is also a stall warning device.

[Bill Greenwood]

Bob, I really don't look forward to cutting or even just drilliing into the wings, they are old! And I don't have a glare sheild, must less space on top of it. But thanks for the info and advice. If you have any photos of the AFS device or its installation maybe you could post them here. I'll also try to look it up online.

And as for as a stall warning, that may be good also, but the feel of the controls and buffet of the airframe, (tailplane) are good ones that don't require looking at an instrument.

[Sam Buchanan]

The biggest reason that I have not installed the AOA is having to cut into the wing, and also shortage of panel space for the indicator. I don't have any EFIS in my plane and don't want one, but if I did have an AOA, I would like to have it stand out and not be buried in another display if I was going to be using for a critical moment like landing.

My LRI probe is mounted to an inspection cover. Other probes have been mounted to a wing strut. Cutting into a wing should not be necessary in order to install an AOA sensor.


My guess, and nothing much to base this on , is that once you start using an AOA you probably find that is and the airspeed indicator are pretty much in agreement. By that I mean that if you do a short field slow landing and come in on the margin at the bottom of the color arc on the AOA, then you will be at the speed that you would use anyway on the airpseed indicator for such a landing. Thus one comfirms the other.

Only if flying weight and density altitude never change. :)

But when weight or DA changes, the plane will stall at a different indicated airspeed. If you intend to land at a short grass strip on a hot day and you have a bubba passenger, what will be the indicated stall speed? Some mental gymnastics may get you close, but the AOA won't lie, it will accurately indicate how close you are to stall regardless of conditions.

And that is the beauty and true safety value of AOA. I had a bug try to fly up the pitot tube and the EFIS went goofy. But the mechanical LRI was untouched and provided the same values I always use for every landing. Sometimes I get asked what landing speed I use in the RV-6. My reply is "not sure, I'm watching the AOA".

[Bill Greenwood]

Sam, next time you are doing landings maybe try a few with a glance at both the airspeed indicator and the AOA indicator, so that you can see if the AOA is telling you anything different than the airspeed. I would think that anyone would do that when they first installed the AOA and did the first flights afterward, unless it is a new plane.

For some large planes like an airliner or transport or bomber, where weight will vary a lot, an AOA may be usefull. I don't have much direct experience with these types.
Of course stall speed varies with weight,and usually in the operators manual stall speeds are given at gross weigth, both clean and as VSO, so they are at the top edge and give you a little margin of safe airspeed if you are heavy.


But does stall speed vary with a change in density altitude and which way?
It has been my experience that stall speed, with the same weight and same configuration ,and same g load is at the same INDICATED airspeed, even if the true airspeed is different.
My Cub for instance stalls at 38mph indicated , power off, and it is the same summer or winter.

As for installation , the plane I'd use it on does not have struts, and no inspection covers on the leading edge, but I may take a look again at more specifics of that. I don't see much point in putting one on a Cub that lands in a few hundred feet anyway.

[Sam Buchanan]

Sam, next time you are doing landings maybe try a few with a glance at both the airspeed indicator and the AOA indicator, so that you can see if the AOA is telling you anything different than the airspeed. I would think that anyone would do that when they first installed the AOA and did the first flights afterward, unless it is a new plane.

In my article I explained how I tested the LRI with two different loadings of the RV-6. Stall speed changed but AOA indication at stall didn't.

And I didn't mean to imply I never look at the airspeed. I usually cross check a couple of times just to make sure nothing weird is happening but when doing a high performance landing (or takeoff) on a short strip the LRI is the primary instrument.


As for installation , the plane I'd use it on does not have struts, and no inspection covers on the leading edge, but I may take a look again at more specifics of that. I don't see much point in putting one on a Cub that lands in a few hundred feet anyway.

Is AOA essential for flight? Of course not, but I guarantee that once accustomed to having it available its value will be appreciated. I really like knowing precisely how close I am to having the wing stall. I even put one on my Legal Eagle for test flights because its stall speed is so low the airspeed indicator falls off the scale. :)

[rleffler]

Bob, I really don't look forward to cutting or even just drilliing into the wings, they are old! And I don't have a glare sheild, must less space on top of it. But thanks for the info and advice. If you have any photos of the AFS device or its installation maybe you could post them here. I'll also try to look it up online.

And as for as a stall warning, that may be good also, but the feel of the controls and buffet of the airframe, (tailplane) are good ones that don't require looking at an instrument.


All the AFS AOA support and installation docs can be found at: http://www.advanced-flight-systems.com/Support/AOAsupport/aoasupport.html

Marketing/Sales data at: http://www.advanced-flight-systems.com/Products/AOA/aoa.html

[Bill Greenwood]

Sam, you wrote that when density altitude changes,"the plane will stall at a different indicated airspeed".

I don't think I am misquoting you, but I don't think that is true.

I think a plane will stall at the same INDICATED AIRSPEED even at different density altitudes, If not, then if we flew from sea level in Tex or Wis to Leadville, Colo which is 10,000 feet airport; we would need to fly our landing approach (normally 1.3 VSO ) at a different indicated airspeed, since the density altitude will be vastly different, by perhaps 10,000 feet not counting temperature changes. If we went from winter in Denver to summer in Scottsdale the temp would be vastly different , but I think the stall would stiil be at the same indicated airspeed( if g load and configuration is the same). Of course the true airspeed will be higher, maybe 15 knots higher at high density altitude ,but we are talking about INDICATED , not true.

That is not the way that I learned to fly and not the way that I do fly. Of course , I may be wrong.
I may have been doing it the wrong way for 30 years, using the same indicated airspeed for each approach, if the weight and wind are not a factor.

What say you? Not on weight change affect on INDICATED STALL SPEED, which we know , but on density alititude affects.

Bob, thanks for the info on installation.
One thing I noticed is that the factory has specific installation locations, even to the 1/4 inch for the planes listed. But what happens if you want to put in a AOA and your plane is not one that they have tested? You don't want to try trial and error locations and and end up with mulitple holes drilled in the wing or even in inspection covers?

That is not how I learned to fly and not how I fly an approach.

[rleffler]

Bob, thanks for the info on installation.
One thing I noticed is that the factory has specific installation locations, even to the 1/4 inch for the planes listed. But what happens if you want to put in a AOA and your plane is not one that they have tested? You don't want to try trial and error locations and and end up with mulitple holes drilled in the wing or even in inspection covers?

I can't help you there. That would be a good question to give Rob Hickman at AFS. They do have an online support forum if you are truly curious. I was fortunate in the I have the same a/c (RV-10) that Rob has. I can copy his parameters and get 99% dialed in, then conduct testing to validate the settings.

bob

[WLIU]

Stall speed will be at the same indicated airspeed given the same weight, CG, and G load, independent of density altitude. The indicated airspeed stall speed changes with aircraft weight and G loading. Remember indicated airspeed is NOT true airspeed.

For your typical light aircraft, you can use indicated airspeed and do not need something with colored lights to tell you that you are not at the appropriate approach airspeed. On your average Piper, or even an RV, an AOA indicator has some cool factor, but adds weight and duplicates the information that you already have. I will observe that far too many pilots do not do a good enough job of identifying and flying the appropriate airspeed on approach for the airplane configuration and weight. If your indicated airspeed is going up and down 15kts on final, adding an AOA indicator will just add the entertainment and distraction of its display moving up and down and changing color in sync with the airspeed indicator's needle. In the end, you will likely get greater benefit from spending the money on avgas and flying patterns to build your stick and rudder skills.

On the topic of where you locate the ports in a wing for a differential pressure based AOA calculation, the location of the ports is dependent on the wing and the shape of its leading edge. If you can find an airplane that has the same wing section that yours has, and the AOA port locations have already been figured out for that wing, then you have a good starting point. But if your flying skills are good enough to calibrate that type of AOA system, you likely do not need that gizmo anyway.

An AOA display is a great help when you launch at a weight of 750,000 lbs and your landing weight is 450,000 lbs. For a Piper Cub, not so much.

Gadgets are fun, but if you are in this for the flying, buy gas.

Best of luck,

Wes
N78PS

[Joe_9253]

A homemade AOA probe can be made for $10 for use with an EFIS. See post #14 of this thread:
http://www.vansairforce.com/community/showthread.php?t=34040
I installed it on my RV-12 with Dynon D-180 and the AOA works great.
Although I have not tried it, the homemade probe should work with a differential pressure gauge (0 to 5" water) with the second port connected to the pitot tube.
Joe Gores

[Joe_9253]

I did a search of past EAA articles and found the following pertaining to AOA:
Better Way to Fly - May 1998 http://www.oshkosh365.org/saarchive/eaa_articles/1998_05_06.pdf
Carrier Pilots' Secret - July 1999 http://www.oshkosh365.org/saarchive/eaa_articles/1999_07_31.pdf
Test Pilot: Angle of Attack - April 2001 http://www.oshkosh365.org/saarchive/eaa_articles/2001_04_20.pdf
Test Pilot: Angle of attack and lift/drag - May 2001 http://www.oshkosh365.org/saarchive/eaa_articles/2001_05_19.pdf
Test Pilot: Angle of Attack - November 2003
REPRINT of Apr 2001 article http://www.oshkosh365.org/saarchive/eaa_articles/2003_11_20.pdf
Shop Talk: Angle of Attack Indicator - December 2008
http://www.oshkosh365.org/saarchive/eaa_articles/2008_12_21.pdf
The December 2008 article by Dave Barker describes how to build the AOA sensor using a hall effect transducer and LED bar graph display.
Below are links to the author's website. Dave Barker's pdf gives more detailed construction details than the EAA magazine article.
http://www.barkeraircraft.com/files/AOA_rDisplay.pdf
http://www.barkeraircraft.com/AOA_kit.html
Although Dave Barker no longer sells AOA kits, he still has some circuit boards available. There is a link to his email address on his website.
Joe Gores

[Markmn]

As someone who has an AOA in a Tecnam P2008 I have to say many are not giving it the credit it is due. Plenty of cubs, LSA etc have stalled it in and lives were lost.

I also was not a believer either until I had one. Knowing how close you are to the stall at all times is a great safety feature. The flashing lights on the AOA inducator get used alot in my aircraft. Mine also has an audio that yells at me just before the stall. Its accuracy is repeatable everytime.

I hear of AOA naysayers who have never had one but I believe you would be hard pressed to find a pilot with a proper working AOA that would give it up.

Mark

[Sam Buchanan]

As someone who has an AOA in a Tecnam P2008 I have to say many are not giving it the credit it is due. Plenty of cubs, LSA etc have stalled it in and lives were lost.

I also was not a believer either until I had one. Knowing how close you are to the stall at all times is a great safety feature. The flashing lights on the AOA inducator get used alot in my aircraft. Mine also has an audio that yells at me just before the stall. Its accuracy is repeatable everytime.

I hear of AOA naysayers who have never had one but I believe you would be hard pressed to find a pilot with a proper working AOA that would give it up.

Mark

You nailed it, Mark.

It seems most who express doubts about the value of AOA in our planes are those who haven't flown with it and learned how to use it to enhance the performance/safety of the aircraft.

And then there is the dubious claim that those who like using AOA are inferior pilots who don't know how to recognize what the plane is telling them.

With the increasing use of EFIS in light planes, this technology will be readily accepted as the norm in years to come. This may be a generational change, but change will occur as now evidenced by the FAA's emphasis on incorporating AOA in light aircraft.

[WLIU]

I will offer the opinion that I don't have doubts about an AOA display, but these days, looking at accidents, I lobby folks that the most important computer in the cockpit is between the pilot's ears. And the best investment is loading that computer with data through structured experience. The accident rate is actually not that bad, but the common theme is NOT that the pilot did not have enough data, but rather that it was not processed by the computer between the pilot's ears.

We can agree to disagree with the notion that limited $$ are more wisely spent on gas rather than a new display.

I will note an indicator of a disturbing trend. The new displays are supposed to present flight info better and help us fly. That said, we had a pilot fly down final looking at the displays, right to impact with the runway. The pilot apparently never looked up from the panel in time to flare - on a clear VFR day.

Enjoy your hi-tech gear.

Best of luck,

Wes
N78PS

[Markmn]

I remember a fairly well known Cub pilot who stalled it in. He did alot of photography or video.

Can anyone help me remember who it was?

Mark

[steveinindy]

I remember a fairly well known Cub pilot who stalled it in. He did alot of photography or video.

Can anyone help me remember who it was?

Mark

I can think of a few. The one that jumps to mind was the mountain flying guru Sparky Imeson.

[WLIU]

I will guess that you are thinking of Sam Lyons, the painter. I believe that his wife died in the crash.

Fly safe.

Merry Christmas,

Wes
N78PS

[Markmn]

No it was someone else. I remember that he was an experienced cub pilot and was doing some slow flight when he stalled at low altitude and was killed. I believe he was by himself but may have had wittnesses to the accident. It was a couple years ago. He was well known as it was in the magazines.

Mark

[gcardinal]

Mark,

You may be referring to Shawn Lunt.

Greg

[Markmn]

Yes it was shawn. He was close to the ground in slow flight when he stalled his super cub and was killed.
Based on my experience with AOA it would have saved him.
My point is that very experienced pilots still stall it in and die.

Im not saying every pilot should be required to have AOA but that it may save your life no matter how good you are.

Mark

[WLIU]

I will suggest that the crash was tragic but thinking that an additional gizmo in the cockpit would have prevented the accident does not address the root cause. The crash sounds like the pilot was not paying attention to either the airspeed indicator or the aerodynamic clues that the airframe was providing. Given that, the addition of an AOA display would not have prevented the accident. The pilot has to actively pay attention to the aircraft.

There was a study just published that says that the switch over to glass cockpits has had no positive affect on the accident rate. Very interesting data.

Technology will not save you from yourself if you are not already making full use of your equipment.

If the computer between the pilot's ears is in pause mode, technology won't make a difference.

Fly safe,

Wes
N78PS

[Sam Buchanan]

If the computer between the pilot's ears is in pause mode, technology won't make a difference.

Fly safe,

Wes
N78PS

I don't think anyone in this thread has posted in opposition to that point regardless of how much we encourage the use of AOA.

And I also don't see how that has anything to do with evaluating the value of using AOA.....we're not discussing brain-dead pilots, but rather individuals who wish to enhance safety with the technology currently available.

AOA works. That is beyond debate. Each pilot decides whether or not they wish to use it.

Sorta like whether or not you chose to navigate with four-range, NDBs, VORs, or WAAS GPS......... ;)

[Markmn]

The way my AOA works it tells you audibly in your headset when you are about to stall in a very attention getting way. ANGLE! ANGLE! PUSH! ANGLE! ANGLE! PUSH!
You do not need to be watching the lights on the panel. I believe the chances are very high it would have saved his life.

I am not saying everyone has to have one of these. I am not selling anything. I am just saying that this product is a game changer in stall avoidance.
Very few of us are going to stall it in but yet we know highly respected and experienced pilots have.


Mark

[steveinindy]

The way my AOA works it tells you audibly in your headset when you are about to stall in a very attention getting way. ANGLE! ANGLE! PUSH! ANGLE! ANGLE! PUSH!

Which model is this?

[Anymouse]

Which model is this?

Although I don't have the voice hooked up in my plane, I believe the Advanced AOA will do this.

[Markmn]

Yes it is advanced flight.

Mark

[Sam Buchanan]

Dynon also provides an auditory alarm with their system. I think the Skyview system actually talks, my D10-A only sends out a tone via the headsets but it definitely gets your attention without having to watch any indicators. I have it plumbed into the LRI probe so the all-mechanical analog indicator is always alive in addition to the Dynon indicator.

[WLIU]

You know, I just realized that certificated aircraft are required to have an audible stall warning system, but that homebuilts are NOT. So in the homebuilt world the addition of an audible AOA warning may in fact be a game changer. This may be one point where homebuilt construction has a safety gap with certificated airplanes. That said, I see that Aircraft Spruce sells a van type stall warner for under $100.

Fly safe,

Wes
N78PS

[Bob Dingley]

You know, I just realized that certificated aircraft are required to have an audible stall warning system, but that homebuilts are NOT. So in the homebuilt world the addition of an audible AOA warning may in fact be a game changer. This may be one point where homebuilt construction has a safety gap with certificated airplanes. That said, I see that Aircraft Spruce sells a van type stall warner for under $100.

Fly safe,

Wes
N78PS

Good point Wes. I also made a discovery about S-LSAs. I was looking at the panel of an S-LSA and it had a placard that flat prohibited intentional stalls and spins. It didn't have a stall warning system either. I checked the factory web site and "stall warning" was not listed as standard or optional equipment. You could, however order a Dynon or other EFIS. But no mention of AOA. I checked the web sites of some others. Same thing. I understand competely that the ASTM standards are much looser than FAR 23.

I learned to fly in Cubs and flew about all the planes of the era. None of the planes in my Guard unit were equiped either. Stalls, slow flight, etc had to be practiced routinely. I spent most of my first 400 to 500 hours on the back side of the power curve as did everyone else. I wonder if my grandkids could safely learn to fly today in the average S-LSA?

Bob

[Frank Giger]

They could learn very well. Indeed, it would force them to pay attention to the sound and feel of the aircraft while looking outside of it rather than staring at a panel.

I'm an outlier, I guess - the few times I flew a Cessna the dang stall horn scared the hell out of me.....not a good thing when in the stages of actually landing the aircraft.

Of course I'm at the stall, you stupid airplane, as the definition of landing is to not be flying any more.

[Sam Buchanan]

Good point Wes. I also made a discovery about S-LSAs. I was looking at the panel of an S-LSA and it had a placard that flat prohibited intentional stalls and spins. It didn't have a stall warning system either. I checked the factory web site and "stall warning" was not listed as standard or optional equipment. You could, however order a Dynon or other EFIS. But no mention of AOA. I checked the web sites of some others. Same thing. I understand competely that the ASTM standards are much looser than FAR 23.

I learned to fly in Cubs and flew about all the planes of the era. None of the planes in my Guard unit were equiped either. Stalls, slow flight, etc had to be practiced routinely. I spent most of my first 400 to 500 hours on the back side of the power curve as did everyone else. I wonder if my grandkids could safely learn to fly today in the average S-LSA?

Bob

We fret about aviation dying, and it is a valid concern. According to the above post and those who think along similar lines, once pilots who learned to fly in real aircraft are dead and gone, aviation will disappear because the younger gene pool won't possess sufficient intelligence to learn how to safely fly the current fleet. Aviation will cease to exist as the younger pilots foolhardy enough to attempt flight kill themselves. Piloting an airplane will eventually be recalled with the same fondness as blacksmithing and alchemy.

We witnessed the same phenomenon with the passing of camera film....now we are stuck with no way to record images.....................

[WLIU]

Actually, I think that you are completely missing the point.

What we see is that a lot of folks are very focused on gadgets and technology and have internalized the idea that gadgets are a substitution for airmanship skills. And so we see high priced airplanes with lots of gadgets in them coming to grief because the pilot was the weak link.

This is not new. My generation called the Beechcraft Bonanza the fork-tailed-doctor-eater. A high performance airplane carrying pilots who had low performance skills. We are starting to see the same history with the new composite super ships that the latest generation of deep-pocketed pilots are buying. The concern is that since we have ignored history, it is repeating itself like the old proverb.

The challenge is coaxing folks into mastering the basic skills as a foundation for employing all of the latest technology. A beautiful house on a lousy foundation falls down within a short time.

So glass cockpits have NOT reduced the accident rate. That fact does not say that glass cockpits are bad. But it says that the pilots using the latest technology are not using the data or are making bad decisions - you pick. So what aircraft or judgemental data is being ignored or misused such on the way to these accidents? And what gadget will will take care of a pilot who is flying low and slow and turning and taking photos instead of flying the airplane?

I LOVE my technology, but Mother Nature seems to break my cool stuff at the worst time. That's when I have to do all that pilot stuff to get home.

Fly safe,

Wes
N78PS

[Bill Berson]

Does the AOA indicator have any correction for flaps down? ( wings stall at less angle with flaps down)

[Bill Greenwood]

Bill Berson, "wings stall at less angle with flaps down".

Do you have this reversed? I have always thought that flaps usually add both lift and drag, thus allowing the plane to fly slower before stalling.
Slower means at a large angle of attack, not less?

Which is correct?

And I don't actually know whether an AOA indicates accurately if the flaps are down, but my guess is that it would have to or it would be pretty useless to have an instrument that was to assist in making a landing approach and have it not work in the landing configuration.
So, I assume that an AOA reads the angle of the wing accurately and it doesn't matter where flaps are set.

[Anymouse]

Does the AOA indicator have any correction for flaps down? ( wings stall at less angle with flaps down)

The Advanced AOA will. You calibrate it for clean and landing configuration.

[Bill Berson]

Bill Berson, "wings stall at less angle with flaps down".

Do you have this reversed? .

No.
The fact that an airfoil or wing will stall a few degrees less when the flap (ailerons are also a kind of flap) is lowered is fundamental knowledge needed to avoid the dreaded stall/ spin.
Have a look at some airfoil wind tunnel plots, or better, read the book STICK and RUDDER.
i read this book every New Year to stay current on the complex nuances of slow flight.
Happy New Year

[Sam Buchanan]

And I don't actually know whether an AOA indicates accurately if the flaps are down, but my guess is that it would have to or it would be pretty useless to have an instrument that was to assist in making a landing approach and have it not work in the landing configuration.
So, I assume that an AOA reads the angle of the wing accurately and it doesn't matter where flaps are set.

The LRI system, which is particularly attractive to operators of certificated aircraft since it doesn't require a 337 for installation (no connections to aircraft power or pitot/static) is an analog indicator and easily calibrated for both clean and landing config.

Something that is being missed by the posts suggesting the simple vane-type switch as opposed to an actual AOA indicator is the way an AOA can display how close you are to aerodynamic stall. The AOA indicates over a continuous range. In my RV-6, the LRI (and Dynon indicator) comes alive at the top of the white arc and drops progressively as airspeed decays and angle of attack increases. If the task at hand calls for safely remaining above any possibility of stall it is easy to move the indicator down the scale to the desired point. But if a max performance landing is needed the indicator can be moved right to the point of stall if the pilot has enough nerve. :) Having the AOA indicator displaying over a wide range of the performance envelope is immensely useful, much more so than a simple switch that remains dormant until it decides to close.

Many users of AOA use their systems to calibrate Vx, Vy, Vbe, Vbg, Vvr, etc.

[Bob Dingley]

We fret about aviation dying, and it is a valid concern. According to the above post and those who think along similar lines, once pilots who learned to fly in real aircraft are dead and gone, aviation will disappear because the younger gene pool won't possess sufficient intelligence to learn how to safely fly the current fleet. Aviation will cease to exist as the younger pilots foolhardy enough to attempt flight kill themselves. Piloting an airplane will eventually be recalled with the same fondness as blacksmithing and alchemy.

We witnessed the same phenomenon with the passing of camera film....now we are stuck with no way to record images.....................

You're right, Sam. I sure did sound like a mossy back curmudgeon. I may have gotten my PPL in a J3, but after a while, I wound up in some very nice glass cockpits. It dosen't take long to become yet another "Child of the Magenta Line."

A flying buddy and I looked at a S-LSA and tho he could order it with various EFIS options, the AOA probe availability is not yet nailed down. A stall warning horn is NA.Thus, the prohibition on intentional practice stalls is a sticking point for him. And I agree. I suggested a used experimental or we build one. As for my grandson, I'm sure that we can find a Cessna in his corner of Texas when he's ready.

Bob

[Sam Buchanan]

Good point Wes. I also made a discovery about S-LSAs. I was looking at the panel of an S-LSA and it had a placard that flat prohibited intentional stalls and spins. It didn't have a stall warning system either. I checked the factory web site and "stall warning" was not listed as standard or optional equipment. You could, however order a Dynon or other EFIS. But no mention of AOA. I checked the web sites of some others. Same thing. I understand competely that the ASTM standards are much looser than FAR 23.

I learned to fly in Cubs and flew about all the planes of the era. None of the planes in my Guard unit were equiped either. Stalls, slow flight, etc had to be practiced routinely. I spent most of my first 400 to 500 hours on the back side of the power curve as did everyone else. I wonder if my grandkids could safely learn to fly today in the average S-LSA?

Bob


We fret about aviation dying, and it is a valid concern. According to the above post and those who think along similar lines, once pilots who learned to fly in real aircraft are dead and gone, aviation will disappear because the younger gene pool won't possess sufficient intelligence to learn how to safely fly the current fleet. Aviation will cease to exist as the younger pilots foolhardy enough to attempt flight kill themselves. Piloting an airplane will eventually be recalled with the same fondness as blacksmithing and alchemy.

We witnessed the same phenomenon with the passing of camera film....now we are stuck with no way to record images.....................


You're right, Sam. I sure did sound like a mossy back curmudgeon. I may have gotten my PPL in a J3, but after a while, I wound up in some very nice glass cockpits. It dosen't take long to become yet another "Child of the Magenta Line."

A flying buddy and I looked at a S-LSA and tho he could order it with various EFIS options, the AOA probe availability is not yet nailed down. A stall warning horn is NA.Thus, the prohibition on intentional practice stalls is a sticking point for him. And I agree. I suggested a used experimental or we build one. As for my grandson, I'm sure that we can find a Cessna in his corner of Texas when he's ready.

Bob

Hi Bob,

Thanks for the reply and glad you picked up on the good-natured sarcasm. :)

Yep, the jury is still out on the suitability of some of the new LSA for primary training, some are definitely better than others. I wish everyone could take primary training in a J-3 or Champ but it is getting difficult to find an instructor that can get affordable insurance to train in a J-3 even if a plane is available.

I used to own a 1940 J-3, flew it for a few hundred hours and loved every one of them. My brother got his private last year and at my prodding is now the proud owner of a 1946 Luscumbe 8E.

There is still hope.....those with the passion for flight will find a way. :)

[Bill Greenwood]

Bill Berson,
I am not home right now so don't have access to my copy of STICK AND RUDDER. It has been some time since I last read it, but I certainly don't recall anything about a plane, any plane stalling at a LOWER ANGLE OF ATTACK, with the flaps down than it does clean. I don't recall any discussion of any angle of attack indicators in the S&R book and, I doubt if AoA indicators were even in much use back when this book was written.

I have probably flown 30 different planes( just a guess) and have never seen or read of one that had a higher stall speed with the flaps down than up. Everyone that I know of has Vs (clean stall speed) as faster than Vso ( stall speed with gear and flaps down, and in some cases the difference may be only a knot or two and in others it may be 10 knots or more.

So, if a plane can fly at a slower airspeed with flaps down before it stalls, than it can clean; then I assume that this is also the ability to fly at a higher angle of attack with flaps down than if clean.

I don't have any wind tunnel plots, but I will ask around and try to come up with more info on this.
As for your way being ""fundamental knowledge, I have been a pilot for 34 years, and what you say is not common knowledge to me. I could be wrong , but I'll bet you a burger at EAA on this.

One further point, many heavy large type planes use partial flaps for takeoff. I think this is to give them more lift and more protection from stall at the slow takeoff speed. If what you say about flaps, stall, and AOA is correct, why would they used partial flaps for takeoff? Your way seems backward. They certainly don't want more drag at takeoff like you do for landing, so they only reason to use them is for more lift and more margin above stall.

[Bill Berson]

Hi Mr Greenwood,
Glad to hear you have a copy of Langewiesche's STICK and RUDDER. Go to page 166 and read about aileron stall. The chapter on ailerons explains how a pilot can cause tip stall by application of aileron at high angle of attack. This can happen because clean wings stall at around 15 degrees angle of attack. But a section of wing with flap or aileron deflected down will stall around 12 degrees angle of attack.
I will look for something to copy here if I can find it. Yes, you owe me a burger.

figure 13-2 shows stall angles both with flaps and without:

http://books.google.com/books?id=i8rNn1vFEd0C&pg=PA199&lpg=PA199&dq=flap+stall+angle&source=bl&ots=u1xDNZgE72&sig=nJ3GcqFGvXoontoc70zFWnOML6s&hl=en&sa=X&ei=guDjUOGWJqaRiAKSqYHYBQ&ved=0CDIQ6AEwATgU#v=onepage&q=flap%20stall%20angle&f=false

go to this website and scroll to page 81 to see an airfoil chart for plain flaps
http://books.google.com/books?id=bSq-cEf0EWsC&pg=PA80&lpg=PA80&dq=flap+stall+angle&source=bl&ots=iEOzvORowN&sig=aSmXMIuKoeWYIr-h6PeFXIdmv0Q&hl=en&sa=X&ei=r9fjUOTDN6b1igLq1IDYCg&ved=0CEMQ6AEwBDgK#v=onepage&q=flap%20stall%20angle&f=false

[Bill Greenwood]

Bill we are not talking about alieron stall, any more than we are talking about deploying air brakes. We are talking about the differences in stall angles with and without flaps. We did not specify, but obviously we have to mean in level flight, not banking or pulling gs, so that the only difference is the flaps.

As I said, I don't have my book handy now, but will look at it next time I am home, and I could certainly be wrong. Glad we did not wager a bottle of Dom Perignon!

And I am just Bill. My Dad was "Mr. Greenwood"

And now I probably won't even be able to make a normal landing again.

[WLIU]

If I can offer some points, I will suggest that a lot depends on what type of flap you have on your aircraft.

All flaps, and drooping ailerons change the camber of the wing. So the Coefficient of Lift (CL) curve changes.

Split flaps are mostly drag but do move the max lift to a lower speed.

Fowler flaps first increase the wing area as they are extended, and then they increase wing camber with further deployment. This is a big change to the lift characteristics of the wing. Max lift moves to a lower speed first because the wing area increases, and hence the wing loading decreases, then it moves to an even lower speed as the wing camber is changed.

Do not confuse the change in the Lift-Drag curve of the wing with a change to the critical angle of attack. For each new wing configuration, caused by a change in the flap position, you have a new Lift-Drag curve that describes the wing. That new graph may or may not move the max lift point in relation to the AOA axis of the graph.

Now a fully functional AOA display is run by an air data computer that has flap position as an input and changes its calculation of AOA as the flap position changes.

The AOA boxes discussed above apparently provide AOA with zero flaps deployed, and maybe AOA with full flaps deployed. So most users are relying on the no flap calibration to keep them out of trouble in the landing approach. The assumption, a valid one, is that when flaps are extended, the installed indicator calculates the same or a higher AOA than the wing is actually flying, which gives them more margin between what the pilot thinks is the AOA and the actual AOA. Make sense?

Fly safe,

Wes
N78PS

[Bill Berson]

Bill we are not talking about alieron stall, any more than we are talking about deploying air brakes. We are talking about the differences in stall angles with and without flaps. .
Kershner's Student pilot manual has a graph to explain flap stall angle. He says: " increasing the angle of attack in the flapped condition would reach its critical angle of attack (stall) well before the clean wing would have problems".

It is true most pilots don't know or think much about this and survive, but some do not. Langewiesche does devote three pages to AOA indicators (page 75). He says the main benefit is training, since most pilots hardly think about angle of attack. His entire book is actually an attempt to explain angle of attack in detail.

Wes,
Yes, each flap is different. Fancy flaps with slats may allow much more angle of attack.

[Bill Greenwood]

I don't know about this Langewiesche guy anyway. Have any of us seen his birth certificate?
His name sounds foreign, faintly German, maybe he was a Luftwaffe plant to confuse our aviators back then. He sure ain't no home grown simple bike mechanic like our real Amerkin Wright boys.

I have it on good authority that he was the aerodynamics expert at Cirrus in charge of making their planes handle so well at the critical stall point. That's why they ended up with parachutes.

[Ron Blum]

There are so many statements that need to be "adjusted" to be correct in this post.

1. Stall AOA is constant (except in high altitude airplanes where the stall AOA decreases slightly with Mach number) for EACH configuration. In other words, each flap setting has a different stall angle of attack.

2. Aircraft (or body or fuselage) stall AOA does DECREASE with increasing flap deflection - because actual airfoil camber is increased, actual chord line changes, zero lift angle decreases (more negative), etc. But, yes, CL is higher and stall speed is lower with increasing flap deflection (to a point).

3. It was also mentioned that with some flaps, the wing area is increased, too. Although this is true, the wing area (or chord length) used for calculations is not changed, and therefore, the wing CL is "falsely" larger (i.e. not really an apples to apples comparison).

4. All AOA devices measure local AOA (which is not necessarily aircraft AOA). In other words, if AOA devices are mounted on the left and right wing tips, they will measure different values as the airplane is rolling.

5. Be aware of AOA devices that measure/display a simple (two port) differential pressure. This is NOT AOA. Here's why. Think of a simple airfoil in a wind tunnel. Put the airfoil at a near stall angle of attack (say 12 degrees). With no airflow, the differential pressure between the top and bottom is zero. Increase airspeed to 30 knots, and the differential pressure goes to 1" of water. Increase airspeed to 60 knots, and the differential pressure goes to 4" of water. Increase airspeed to 120 knots, and the differential pressure goes to 16" of water. The AOA hasn't changed.

6. Certified airplanes (part 23 & 25) are no longer allowed to use a stall warning that is only visual. Piper did years ago, but the regulations have been carified to prevent this. The reason for this is what has been stated in this forum - the pilot should be looking outside ... that is why horns and stick shakers are used.

7. As for "real" pilots being able to fly by the seat of their pants, this may be true ... in some airplanes, when G-loads aren't introduced. This also ASSUMES that the airplane will give you a warning before it stalls. Newer airplanes/airfoils which are higher performance may not be designed to do this ... especially those with laminar flow wings.

Questions, comments and criticisms are greatly apprciated.

PS. Most certificated airplanes that use AOA for stall warning use normalized AOA, and it is also incorporated into the airspeed tape, but they still have a warning horn or stick shaker (non-visual warning)

[Bill Berson]

Well said Ron,
I suppose ice on the leading edge would be classified as "new configuration"

[Bob Dingley]

I don't know about this Langewiesche guy anyway. Have any of us seen his birth certificate?
His name sounds foreign, faintly German, maybe he was a Luftwaffe plant to confuse our aviators back then. He sure ain't no home grown simple bike mechanic like our real Amerkin Wright boys.

I have it on good authority that he was the aerodynamics expert at Cirrus in charge of making their planes handle so well at the critical stall point. That's why they ended up with parachutes.

Bill, the plot is deeper than even you can imagine.

I read a re-print of an old-old news item from the Portland (Maine) Press Herald from WW2. My old stomping grounds. The article reported that a brand new Vought Sikorsky F4U made a dead stick landing near the boardwalk at Old Orchard Beach. The paper interviewed the test pilot, Wolfgang Langewiesche. He said that he departed Bridgeport, CT and was putting some time on this new bird when the engine quit, so he put it on the beach in front of that joint that sells those great lobster rolls. They also interviewed a nearby clam digger crew that witnessed the whole thing. They say he had the optimum angle of attack all the way down. No damage.

The clam diggers further opined that "he swiped the plane and was headed for those French islands off the Maine coast. You know, St.. Pierre and Miquilon." They were certain that he intended to give it to any Vichy authorities there." After all, he had an accent!" It may have even been a birdcage model.

Bob

[steveinindy]

7. As for "real" pilots being able to fly by the seat of their pants, this may be true ... in some airplanes, when G-loads aren't introduced. This also ASSUMES that the airplane will give you a warning before it stalls. Newer airplanes/airfoils which are higher performance may not be designed to do this ... especially those with laminar flow wings

Would mass balancing the ailerons or elevator to avoid flutter negatively effect the "feel" that so many of the older pilots talk about relying upon? I would wager a guess that they would be less likely to clatter or vibrate in disrupted airflow.


PS. Most certificated airplanes that use AOA for stall warning use normalized AOA, and it is also incorporated into the airspeed tape, but they still have a warning horn or stick shaker (non-visual warning)

Would this be why we see the certificated planes using the "vane-type" AoA systems rather than the ones you see listed in Aircraft Spruce?

[Matt Gonitzke]

Would mass balancing the ailerons or elevator to avoid flutter negatively effect the "feel" that so many of the older pilots talk about relying upon? I would wager a guess that they would be less likely to clatter or vibrate in disrupted airflow.

My glider has an all-flying V-tail that for obvious reasons is mass-balanced, and it has much better feel than many other aircraft I have flown. Thermals will shake the stick a little bit, which is something I have not really noticed in other aircraft.

[steveinindy]

My glider has an all-flying V-tail that for obvious reasons is mass-balanced, and it has much better feel than many other aircraft I have flown. Thermals will shake the stick a little bit, which is something I have not really noticed in other aircraft.

Interesting.

I have debated a trimmable horizontal stabilizer for my design to do away with the need for trim tabs on the elevators at least. I am also going with a mass balanced set of ailerons and rudder. Such is one of the advantages (and issues!) that comes with a clean sheet design.

[WLIU]

For what is worth, jacking the leading edge of the horizontal stab up and down comed with its own set of issues. Both Cessna and Piper did it and then went back to trim tabs. A moveable stab turns out to be mechanically more complex, heavier, and you have the control creep issue. Both moving stabs and trim tabs have to hold the settings that the pilot selects. Cessna found out that jackscrews creep as much as a trim tab mechanism, requiring the designer create artificial friction in the linkage.

So you may want to compare the parts count, parts complexity, and weight of the two approaches.

Best of luck,

Wes
N78PS

[Ron Blum]

A. Yes, ice on the leading edge is a new configuration (most AOA computers have a setting for each flap setting with and without ice ... that's 8 configurations for most higher performance airplanes).

B. Mass balancing is only for flutter (and flight controls should be protected from accumulating ice on their leading edges (even the aerodynamic counterbalances on the tips). Remember that this is MASS balanced, they are still not aerodynamically balanced (or they would be neutrally (or un) stable). In other words, gusts will always shake the flight controls.

C. Trimmable stabs are not known for being lighter, they are know for being more aerodynamically efficient. All the bigger airplanes have them to reduce trim drag in cruise. It matters to the airlines that are operating there all the time. Even 1% cruise fuel efficiency gain is a big deal.

D. A "PS" to the icing. Certificated airplanes have to stall within 3 knots of the clean configuration or it has to be published in the AFM, too.

[steveinindy]

A. Yes, ice on the leading edge is a new configuration (most AOA computers have a setting for each flap setting with and without ice ... that's 8 configurations for most higher performance airplanes).

Fun, fun. Probably makes flight test a rockin' good time.


B. Mass balancing is only for flutter (and flight controls should be protected from accumulating ice on their leading edges (even the aerodynamic counterbalances on the tips). Remember that this is MASS balanced, they are still not aerodynamically balanced (or they would be neutrally (or un) stable). In other words, gusts will always shake the flight controls.

Right. I wonder if this might be an application for those electrical anti-ice coatings (ThermaWing) as a way of protecting the leading edge of flaps and control surfaces.


C. Trimmable stabs are not known for being lighter, they are know for being more aerodynamically efficient. All the bigger airplanes have them to reduce trim drag in cruise. It matters to the airlines that are operating there all the time. Even 1% cruise fuel efficiency gain is a big deal.

In my book, when you're burning 20+ GPH in cruise, a little gain like that can be important too regardless of whether you're in a high-end GA aircraft, a business jet or airliner. A little extra weight and mechanical complexity might be worthwhile.


For what is worth, jacking the leading edge of the horizontal stab up and down comed with its own set of issues. Both Cessna and Piper did it and then went back to trim tabs. A moveable stab turns out to be mechanically more complex, heavier, and you have the control creep issue. Both moving stabs and trim tabs have to hold the settings that the pilot selects. Cessna found out that jackscrews creep as much as a trim tab mechanism, requiring the designer create artificial friction in the linkage.

So you may want to compare the parts count, parts complexity, and weight of the two approaches.

Thanks for the information. I wasn't aware of Cessna's experience. I will have to look into that when it comes to the final detail design.

[Ron Blum]

Leading edges of rudders, elevators and ailerons are protected by the front section of their stabilizer/wing. New procedures (since the ATR accident) set a minimum holding speed in icing conditions (puts the ice accumulation where it will be anti/de-iced well. In addition, flaps are not to be used until on short final (if at all) ... unles you can prove that the leading edges are clean.

[Anymouse]

For what is worth, jacking the leading edge of the horizontal stab up and down comed with its own set of issues. Both Cessna and Piper did it and then went back to trim tabs. A moveable stab turns out to be mechanically more complex, heavier, and you have the control creep issue. Both moving stabs and trim tabs have to hold the settings that the pilot selects. Cessna found out that jackscrews creep as much as a trim tab mechanism, requiring the designer create artificial friction in the linkage.

Had the locking mechanism on a stabilator trim break on me shortly after takeoff in a C-182 (1959 model??) a bunch of years back. Everything I moved the elevator, the stabilator would reorient itself back to the path of least resistance. I ended up having to hold the trim wheel in order to keep the aircraft from porpoising. It made for an interesting landing, especially since the trim wheel was located on the floor.

[wacoc8]

Leading edges of rudders, elevators and ailerons are protected by the front section of their stabilizer/wing. New procedures (since the ATR accident) set a minimum holding speed in icing conditions (puts the ice accumulation where it will be anti/de-iced well. In addition, flaps are not to be used until on short final (if at all) ... unles you can prove that the leading edges are clean.

Most aircraft manufacturers that build FAR 23 aircraft are now limiting all approaches in known icing or if you have visible ice on the airframe to something less than full flaps. The reason is not due to ice on the wing but on the tail. The tail can stall prior to the wings with a load of ice.....and you can't see the tail from the two front seats. The worst time to change the configuration would be on short final. You will not recover. There are numerous NTSB reports to prove this. The one that comes to mind first is the Saberliner that crashed outside Detroit in the late 80's early 90's that was operated by the U.S. Marshall Service. I remember that one cuz I was flying a Saberliner 60 at the time.
As for the AOA, great explanation Ron. I know I could not have explained it that well, and I fly with one all the time.

Dave

[Ron Blum]

Although I agree with Dave, it could be residual contamination on either the wing or tail. The "Dove" that NASA uses as a test vehicle is very tail power limited in stall (in icing ... and it flies squirrelly even when it is clean). The ATR had a ridge of ice form ahead of the ailerons. Each airplane is a little different. Wing ice normally just increases the stall speed. Tail ice on the other hand could make the airplane unstable/uncontrollable. Crap. Back to the original topic.

Ice CAN make the stall AOA a little higher and stall speeds a little lower (think little vortex generators), but this is more true on older airfoils. With a modern airfoil, the stall speeds will go up and the stall AOA will go down.

[Sam Buchanan]

This is an old thread but the emphasis on incorporating angle of attack indicators in GA aircraft continues to gain momentum. Below is a news blurb from AvWeb. The complete report is here (http://www.avweb.com/pdf/faaaopaaoareport.pdf).



FAA/AOPA Committee Pushes AOA






By Glenn Pew (http://www.avweb.com/cgi-bin/udt/im.author.contact.view?client_id=avflash&story_id=208430&title=FAA/AOPA%20Committee%20Pushes%20AOA&author=Glenn%20Pew&address=http%3A//www.avweb.com/avwebflash/news/faa%5Faopa%5Faoa%5Ffatal%5Faccidents%5F208430%2D1. html&summary=A%20report%20on%20approach%20and%20landing %20loss%2Dof%2Dcontrol%20accidents%20has%20emerged %20from%20a%20work%20group%20co%2Dchaired%20by%20t he%20FAA%20and%20AOPA%2C%20recommending%20that%20G A%20%22embrace%20to%20the%20fullest%20extent%22%20 angle%2Dof%2Dattack%20%28AOA%29%20systems%20and%20 work%20to%20improve%20pilot%20decision%20making.%2 0The%26%23160%3Bwork%26%23160%3Bgroup%20advises%20 the%20General%20Aviation%20Joint%20Steering%20Comm ittee.%20Its%20focus%20was%20derived%20from%20an%2 0FAA%20overview%20that%20found%20loss%20of%20contr ol%20accounted%20for%2040.2%20percent%20of%20fatal %20general%20aviation%20accidents%20that%20took%20 place%20from%202001%20to%202010.%20Particular%20ar eas%20of%20concern%20included%20flying%20after%20a %20period%20of%20inactivity%20and%20transition%20t raining%2C%20as%20well%20as%20pilot%20decision%2Dm aking.), Contributing Editor, Video Editor




http://www.avweb.com/images-avweb/clearpixel.gif




http://www.avweb.com/newspics/aoa1.gif

A report on approach and landing loss-of-control accidents has emerged from a work group co-chaired by the FAA and AOPA, recommending that GA "embrace to the fullest extent" angle-of-attack (AOA) systems and work to improve pilot decision making. The work group advises the General Aviation Joint Steering Committee. Its focus was derived from an FAA overview that found loss of control accounted for 40.2 percent of fatal general aviation accidents that took place from 2001 to 2010. Particular areas of concern included flying after a period of inactivity and transition training, as well as pilot decision-making.

Pilot decision-making remains a focus of safety concerns in general, as 85 percent of fatal accidents can be traced to pilot actions, according to AOPA. The report notes that controlled flight into terrain accidents have decreased and it attributes that improvement to new in-cockpit technology like terrain-aware GPS units. AOA systems, says the report, offer pilots awareness of their margin over stall and account for weight and acceleration differences, by design. The report notes that AOA systems offer substantial safety benefits but notes that cost and regulations may produce barriers for the pilots of light aircraft. The FAA "will need to identify the right level of certification," it says. It notes that the FAA should address these issues "with streamlined processes" for certifying and installing new technology that offers "a high probability of safety benefits" balanced against "low safety risk."

[WLIU]

"It notes that the FAA should address these issues "with streamlined processes" for certifying and installing new technology that offers "a high probability of safety benefits" balanced against "low safety risk."

This is the BIG problem. The process holds safety innovation back rather and facilitates it. I deal with field approvals and the process is slowing down, not speeding up. Unfortunately, "simplification" of a regulatory process often involves more paperwork.

Best of luck,

Wes
N78PS

[Ron Blum]

Actually, the FAA IS trying to streamline the process and make the process less expensive. I am on the ASTM committee, and there is a lot of talk about this topic. It needs to be done right, though, and not all AOA systems out there are measuring AOA, and in addition, the highest AOA at stall is not with flaps extended.

[WLIU]

Thanks for the optimism. Last year I submitted a 337 Field Approval package that requested the installation of an FAA-PMA alternator on my airplane. That part is STC-ed for a number of airplanes, but not mine. All of the paperwork was complete with t's crossed and i's dotted. Sounds cut-and-dry, yes?. My FSDO still took 10 months to process it. Whatever the policy, it feels like they don't give this type of customer service any priority.

Best of luck,

Wes
N78PS

[Ron Blum]

Safety is the FAA's leading priority. The saying goes, "The regulations are written in blood." In other words, when there is a major accident, there will most likely be new regulations. Stall/spin has been an issue since before the beginning of manned flight. AF447 and the G650 Flight Test accident have recently brought to light some of these issues again. With that said, though, most stall/spin accidents are below 800' AGL in the pattern (and more likely below 400' AGL). Although I believe in spin training, stall recognition is more important in these particular situations. There is no reason to be flying your airplane around in normal operation near stall. Airplane peformance is based on 1.2Vstall on takeoff/climb and 1.3Vstall on approach.

[Tanille Elaine DeLair]

Has anyone done an AOA installation in fabric wings? Any tips you would like to share?

[Ron Blum]

Has anyone done an AOA installation in fabric wings? Any tips you would like to share?

An AOA installation is no different between fabric, aluminum, composite, wood, etc. Any installation off the surface will be the same. A differential pressure on the surface may be affected due to the fabric vibrating, unsteady flow and the very small differential pressures. If I may ask, what are you thinking?