Continental TurboProp crash inbound for Buffalo
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First, with regard to Pool’s comment about groundings: we did effectively ground the ATR during the winter of 94 to 95 by prohibiting its operation in icing conditions until a redesigned set of boots had been retrofitted. I was there, and it was not a happy time, but it was the right thing to do.
This thread is so long that my next comments are statistically almost sure to be repetitive, so please forgive me if that is the case.
There may be some confusion about the nature of a stick pusher. FAA Advisory Circular 25-7A, Flight Test Guide For Certification Of Transport Category Airplanes, never refers to a stick pusher as a stall “avoidance” device. The promulgation of this myth in training may be part of the problem. Rather, the AC identifies the stick pusher as one of several types of stall identification devices. The role of the pusher as a stall identification device is thoroughly explored by Dave Davies in Handling the Big Jets.
A conventional marriage between airfoil section and configuration results in an early flow separation, consequent aerodynamic buffet (felt through the control column in the case of unboosted elevators), and a pronounced nose down pitch at the stall. More contemporary combinations of airfoil section and configuration, as well as wing sweep, may seriously compromise the traditional stall warning, identification and characteristics. There may be no early aerodynamic buffet, or due to powered elevators and/or T-tail, the turbulent flow may not be felt as clearly as need be. The actual stall may not yield a nose down pitch. Indeed, it may result in a nose-up pitch in some swept wing cases. Hence the stick shaker, which is intended to artificially replace the early aerodynamic buffet, and the stick pusher, which is likewise intended to replace the traditional pitch down of a conventional airfoil section. The general idea was to replicate the conventional stall behavior.
For a good review of this, take a look at FAR 25.201 and 25.203, AC 25-7A and, if you can get one, Davies wonderful book.
Davies makes one point that is very powerful and, in the Colgan case, poignant. On page 135, he says, “Get to know what the push feels like during training.” As I sat in the audience at the NTSB Public Hearing for the Colgan case, I listened to testimony to the effect that Captain Renslow had been exposed to the Saab 340 stick pusher, but not the Q400 pusher. I thought this to be very sad. In an earlier part of my career, I was a check airman on the Metroliner. The early Metro II’s would periodically require an inflight calibration of the stall warning horn, AoA indicator and stick pusher. This allowed me to develop some expertise in performing a sort of falling leaf at around 85 knots while the technician in the right seat rapidly twirled his little jeweler’s screwdriver to make the adjustments. As you might imagine, this system was soon replaced through an STC allowing bench calibration. But the experience with it led me to always demonstrate a stall right into the pusher during while training new captains and first officers. I like to think that everyone I trained would have recognized the pusher for what it was, and been comfortable managing it.
I cannot understand why the industry finds this so difficult. If we did it in the airplane, it can surely be done in the simulator.
This thread is so long that my next comments are statistically almost sure to be repetitive, so please forgive me if that is the case.
There may be some confusion about the nature of a stick pusher. FAA Advisory Circular 25-7A, Flight Test Guide For Certification Of Transport Category Airplanes, never refers to a stick pusher as a stall “avoidance” device. The promulgation of this myth in training may be part of the problem. Rather, the AC identifies the stick pusher as one of several types of stall identification devices. The role of the pusher as a stall identification device is thoroughly explored by Dave Davies in Handling the Big Jets.
A conventional marriage between airfoil section and configuration results in an early flow separation, consequent aerodynamic buffet (felt through the control column in the case of unboosted elevators), and a pronounced nose down pitch at the stall. More contemporary combinations of airfoil section and configuration, as well as wing sweep, may seriously compromise the traditional stall warning, identification and characteristics. There may be no early aerodynamic buffet, or due to powered elevators and/or T-tail, the turbulent flow may not be felt as clearly as need be. The actual stall may not yield a nose down pitch. Indeed, it may result in a nose-up pitch in some swept wing cases. Hence the stick shaker, which is intended to artificially replace the early aerodynamic buffet, and the stick pusher, which is likewise intended to replace the traditional pitch down of a conventional airfoil section. The general idea was to replicate the conventional stall behavior.
For a good review of this, take a look at FAR 25.201 and 25.203, AC 25-7A and, if you can get one, Davies wonderful book.
Davies makes one point that is very powerful and, in the Colgan case, poignant. On page 135, he says, “Get to know what the push feels like during training.” As I sat in the audience at the NTSB Public Hearing for the Colgan case, I listened to testimony to the effect that Captain Renslow had been exposed to the Saab 340 stick pusher, but not the Q400 pusher. I thought this to be very sad. In an earlier part of my career, I was a check airman on the Metroliner. The early Metro II’s would periodically require an inflight calibration of the stall warning horn, AoA indicator and stick pusher. This allowed me to develop some expertise in performing a sort of falling leaf at around 85 knots while the technician in the right seat rapidly twirled his little jeweler’s screwdriver to make the adjustments. As you might imagine, this system was soon replaced through an STC allowing bench calibration. But the experience with it led me to always demonstrate a stall right into the pusher during while training new captains and first officers. I like to think that everyone I trained would have recognized the pusher for what it was, and been comfortable managing it.
I cannot understand why the industry finds this so difficult. If we did it in the airplane, it can surely be done in the simulator.
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Hmm...
I don't propose to read stuff written in such a violently unreadable style as that rant a few posts ago, sorry. That would be like trying to have a chat with the guy out in the street with a sign reading "The End is Nigh!" When I see something written in that style (?) I think, "Here we have someone with SERIOUS ISSUES THAT DEMAND OUR IMMEDIATE ATTENTION," way too serious for me to deal with.
70% of statistics are made up off the top of one's head, just like the 70% of "airline pilots" who are going to give an almighty heave back on the controls when the speed is sinking, the shaker is going and now the pusher is, uh, pushing! Where do you find so many guys so tired of life that they try to end it all with a self-provoked deep stall that flies in the face of everything we are taught to do? The only one I ever heard of is the unfortunate Captain Renslow there. Even the NTSB guy on the report panel couldn't explain what he did.
This is like I drop something in your lap, you clap your legs together, assuming you are a male. It is a well-learned response, almost a reflex action. Well, same with the cues for a stall, you relax the back pressure and add power and that is just for starters. Remember what we have to learn before we go solo? Slow flight, stalls and stall recovery and most students get that within the first few hours of primary training; if they cannot get that right that pretty much ends "learning to fly" in fact!
Ever heard of Henri Mignon and his "flying flea"? He decided normal aircraft were just too darn complicated so he started leaving stuff out until he got what he liked. No stick shaker or pusher for that boy either! He was French, of course...
The rest of us have had to learn to cope with normal slow flight, pre-stall and stalls, eh, Matey? If you seriously think that 70% of all Airline Transport Pilot Licence holders are going to sit there unaware of the airspeed dropping and the shaker rattling the bejusus out of the yoke so that the pusher firing comes as a total shock to them... You are having us on there, right?
I just happen to have a copy of Captain Davies' book right here, the one where he writes that "the stick pusher must always prevent the natural stall being reached in service." (P.132) You know, that reads an awful lot like a stall protection device (what it is) and not a stall notification device (what the shaker is). That must be why you get the shaker pre-stall and the pusher to prevent the stall itself, I guess. The pusher had to be invented to prevent an unrecoverable deep stall, a most unwelcome phenomenon that came to light in some of the early t-tail jets, when the tail was blanked at high AoA so that there was no nose-down pitch authority available to the pilot for stall recovery. Some guys ended up doing a very convincing imitation of a toolbox with the lid open, crashing in a near-vertical descent in what Davies called a "super-stall," what we now call a deep stall.
If you really, really must stall any old airplane fitted with a stick pusher, well, some you can get away with that, others you will DIE! I wouldn't put that little aeronautical insight out there without pointing this fact out to the unwary, if I were you. Think of spins, which you can do in Cessna 150, no sweat. Don't try one in your Metroliner, but you probably know that already. Like a deep stall in some jets, you can get into one no problem; it is the recovery that generally is going to be im-bleedin'-possible.
70% of statistics are made up off the top of one's head, just like the 70% of "airline pilots" who are going to give an almighty heave back on the controls when the speed is sinking, the shaker is going and now the pusher is, uh, pushing! Where do you find so many guys so tired of life that they try to end it all with a self-provoked deep stall that flies in the face of everything we are taught to do? The only one I ever heard of is the unfortunate Captain Renslow there. Even the NTSB guy on the report panel couldn't explain what he did.
This is like I drop something in your lap, you clap your legs together, assuming you are a male. It is a well-learned response, almost a reflex action. Well, same with the cues for a stall, you relax the back pressure and add power and that is just for starters. Remember what we have to learn before we go solo? Slow flight, stalls and stall recovery and most students get that within the first few hours of primary training; if they cannot get that right that pretty much ends "learning to fly" in fact!
Ever heard of Henri Mignon and his "flying flea"? He decided normal aircraft were just too darn complicated so he started leaving stuff out until he got what he liked. No stick shaker or pusher for that boy either! He was French, of course...
The rest of us have had to learn to cope with normal slow flight, pre-stall and stalls, eh, Matey? If you seriously think that 70% of all Airline Transport Pilot Licence holders are going to sit there unaware of the airspeed dropping and the shaker rattling the bejusus out of the yoke so that the pusher firing comes as a total shock to them... You are having us on there, right?
I just happen to have a copy of Captain Davies' book right here, the one where he writes that "the stick pusher must always prevent the natural stall being reached in service." (P.132) You know, that reads an awful lot like a stall protection device (what it is) and not a stall notification device (what the shaker is). That must be why you get the shaker pre-stall and the pusher to prevent the stall itself, I guess. The pusher had to be invented to prevent an unrecoverable deep stall, a most unwelcome phenomenon that came to light in some of the early t-tail jets, when the tail was blanked at high AoA so that there was no nose-down pitch authority available to the pilot for stall recovery. Some guys ended up doing a very convincing imitation of a toolbox with the lid open, crashing in a near-vertical descent in what Davies called a "super-stall," what we now call a deep stall.
If you really, really must stall any old airplane fitted with a stick pusher, well, some you can get away with that, others you will DIE! I wouldn't put that little aeronautical insight out there without pointing this fact out to the unwary, if I were you. Think of spins, which you can do in Cessna 150, no sweat. Don't try one in your Metroliner, but you probably know that already. Like a deep stall in some jets, you can get into one no problem; it is the recovery that generally is going to be im-bleedin'-possible.
Last edited by chuks; 9th Feb 2010 at 17:12.
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Nice to see people Quoting from "Handling the Big Jets". DP Davies Book, along with "Fly the Wing" by Webb are mandatory in my mind for good airline pilots
I'll bet no one at Colgan has read the two above books.
PS...metroliner SAS clutch...what a piece of #@$%^
I'll bet no one at Colgan has read the two above books.
PS...metroliner SAS clutch...what a piece of #@$%^
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Once upon a time I was flying a Shorts 3-60 (in the RHS) when the shaker came on and stayed on continuously.
We were descending IMC on an early morning freight flight into BEB.
I may as well add that this a/c had no auto-anything or even a flight director. We were going fast for us, at least we thought we were (!) but why the shaker?
Had to hand fly it for about 10 mins like that by which time I don't know which was shakier, me or the plane.
Fixed it by (the Capt.) pulling the CB.
Just to say, these things are not infallible.
We were descending IMC on an early morning freight flight into BEB.
I may as well add that this a/c had no auto-anything or even a flight director. We were going fast for us, at least we thought we were (!) but why the shaker?
Had to hand fly it for about 10 mins like that by which time I don't know which was shakier, me or the plane.
Fixed it by (the Capt.) pulling the CB.
Just to say, these things are not infallible.
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PBS Frontline
PBS Frontline will air "Flying Cheap" with an investigation of this flight. It might be worth look-see as Frontline is usually very thorough and fair in its presentations
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"Handling the big jets" was one of the most informative books I have read about obscure questions that weren't addressed elsewhere. Things like low speed mach buffet at altitude puzzled me until I read that book. I was flying a Lockheed Jetstar then, not in the airline group that gets all the training, so you had to train yourself. Found out that the airline training isn't that deep so am happy I learned it then.
Knowledge is every pilots responsibility. Don't expect the airline training program with their cost analysis team to teach you more than what is required to be legal. Sully didn't do what he did by airline training, he did it himself.
Knowledge is every pilots responsibility. Don't expect the airline training program with their cost analysis team to teach you more than what is required to be legal. Sully didn't do what he did by airline training, he did it himself.
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Another shaker-caused crash -- TWA flight 843 at JFK.
TWA Flight 843 - Wikipedia, the free encyclopedia
TWA Flight 843 - Wikipedia, the free encyclopedia
Originally Posted by Mansfield
Flight Test Guide For Certification Of Transport Category Airplanes, never refers to a stick pusher as a stall “avoidance” device.
Originally Posted by DP Davies
It follows from all these considerations, therefore, that the stick pusher must always prevent the natural stall being reached in service.
Originally Posted by DP Davies
If a stick pusher is used to meet the stall requirements it must provide two qualities: clear and unmistakable identification of the stall, by a sharp positive forward movement of the control column, and an adequate nose down pitch by the aircraft.
Originally Posted by Pool
We all know about the shortcomings of big props in severe weather (ATR72 Q400). Was there ever a major grounding and redesign?
Last edited by Clandestino; 10th Feb 2010 at 05:09. Reason: Typo... severe one
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Back in the 70's we flew a Lear 23 that had a stick pusher that sometimes went off during flair. We turned it off on close final to not screw up the landing so it was kind of worthless. Otherwise we would have landed on the nose wheel if we let it do it's job.
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Originally Posted by Diamond Bob
Another shaker-caused crash -- TWA flight 843 at JFK.
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airrabbit is quite right. the TWA L1011 in question would have flown just fine...knowing if a system like a shaker or pusher is in action for the wrong reason is part of the pilot's job.
certainly a pilot might have a moment of "what the F..." but a quick look at the airspeed and other instruments would garner a response like: Stick Shaker in error...ignore...get the checklist out.
I had an eroneous shaker on takeoff...ignored it and returned to home base with a normal landing...mx dried out the circuit with a hair dryer and it worked fine.
IF the crew of Colgan 3407 had done NOTHING when the pusher pushed...absolutely nothing...more people would have survived a crash in an unstalled airplane than what did happen.
A good pilot is constantly (and on a subconscious level) analyzing many many things during a landing approach (see Davies book) watching out for a stall should be high on the list...
certainly a pilot might have a moment of "what the F..." but a quick look at the airspeed and other instruments would garner a response like: Stick Shaker in error...ignore...get the checklist out.
I had an eroneous shaker on takeoff...ignored it and returned to home base with a normal landing...mx dried out the circuit with a hair dryer and it worked fine.
IF the crew of Colgan 3407 had done NOTHING when the pusher pushed...absolutely nothing...more people would have survived a crash in an unstalled airplane than what did happen.
A good pilot is constantly (and on a subconscious level) analyzing many many things during a landing approach (see Davies book) watching out for a stall should be high on the list...
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A good pilot is constantly (and on a subconscious level) analyzing many many things during a landing approach (see Davies book) watching out for a stall should be high on the list...
Psychophysiological entity
Once upon a time I was flying a Shorts 3-60 (in the RHS) when the shaker came on and stayed on continuously.
Conflicting visual and or aural inputs, are in themselves, very dangerous.
I guess I'm getting to be one of the last lot to be trained on the real aircraft with stalls taken through to the push. (BAC 1-11) It really was a smooth procedure, with the Claxon leaving you with no doubts that it had happened.
The Stains accident hadn't happened by then, (18/6/72) but of course Mike Lithgow's deep stall had. (G-ASHG. 2/10/63) We had all seen pictures of the very short impact site and were acutely aware of the danger. In Davis' later editions, he talks almost passionately about more training in the real aircraft. I can not imagine flying without that kind of experience, yet I've just tonight, watched an hour long program on PBS about this accident. Frontline. Flying Cheap.
One guy, during an extensive face to face interview, said that he'd got his command at 500 hours. His F/O was in flight school with him and had 400.
All in all the program was damning. But then, so are many sensationalistic types of documentary, but it is obvious that there have to be huge changes. As one who is mystified how airline finances work in present times, I can not even imagine how the industry can afford to totally restructure its training standards and crew experience levels for the better.
An Applicable Chapter in Freakonomics
Why Crack Dealers Live with their Mothersdemonstrates interesting economic similarities between dealing crack and flying airplanes.
There is a vast pyramid from associate gang members paying monthly membership to street level dealers making little more than welfare to the local gang leader making $100K tax free to the directors making millions.
The authors characterise this situation as a tournament with low level aspirants tolerating unliveable wages and dangerous working conditions for a shot at the very well paid gang leader position.
Instructors and feeder airline pilots tolerate the same low wages and poor working conditions as a means to get into a well paid jet job.
This is very much a North American situation as many young people can pay their way onto that low rung of the career ladder. Any flying position can attract hundreds of resumes. In earlier times, North American airlines were able to fill a major portion of their positions from retired military, but that pool has shrunk considerably.
In Europe, self-sponsorship is far more expensive; so we find many airlines taking on cadets and training them ab initio.
There is a vast pyramid from associate gang members paying monthly membership to street level dealers making little more than welfare to the local gang leader making $100K tax free to the directors making millions.
The authors characterise this situation as a tournament with low level aspirants tolerating unliveable wages and dangerous working conditions for a shot at the very well paid gang leader position.
Instructors and feeder airline pilots tolerate the same low wages and poor working conditions as a means to get into a well paid jet job.
This is very much a North American situation as many young people can pay their way onto that low rung of the career ladder. Any flying position can attract hundreds of resumes. In earlier times, North American airlines were able to fill a major portion of their positions from retired military, but that pool has shrunk considerably.
In Europe, self-sponsorship is far more expensive; so we find many airlines taking on cadets and training them ab initio.
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Oh really?
So if this rather dozy crew had turned off the switch without adding power, the shaker would have activated at a somewhat lower speed as the speed continued to drop, then the pusher would have activated, startling the crew so that the PF still would have pulled back hard on the control column while the PNF raised the flaps and... same sad result I guess. The problem there was not primarily with the aircraft, as the accident report clearly states.
Someone said of the Piper Cub that it was the safest airplane he knew of because "it can just barely kill you." Perhaps it is so that we have a generation of people who just mark time in the cockpit until they get that dream job. Really, if you do not approach each airplane with respect, learning all that you can about it, not just enough to get through your next sim check... they can and do bite. That's part of the fun, actually, mastering something slightly dangerous. If you think one of these highly automated modern machines is easy and fun to fly, just a matter of pushing a few buttons, perhaps you really should think about a career in photocopy machine maintenance instead.
Someone said of the Piper Cub that it was the safest airplane he knew of because "it can just barely kill you." Perhaps it is so that we have a generation of people who just mark time in the cockpit until they get that dream job. Really, if you do not approach each airplane with respect, learning all that you can about it, not just enough to get through your next sim check... they can and do bite. That's part of the fun, actually, mastering something slightly dangerous. If you think one of these highly automated modern machines is easy and fun to fly, just a matter of pushing a few buttons, perhaps you really should think about a career in photocopy machine maintenance instead.
Last edited by chuks; 11th Feb 2010 at 06:34. Reason: Attempt to make clear what point I was making!
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Interesting Show
Frontline are a well respected organisation on this side of the pond...this is worth watching.
FRONTLINE: flying cheap: watch the full program | PBS
FRONTLINE: flying cheap: watch the full program | PBS
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'Colgan 3407 experienced an erroneous stick shaker too'
No it was not erroneous - the system operated exactly as it was supposed to.
It was the inability of the crew to correctly fly the aircraft for the conditions they were in.
A lot of talk about stick shake / pushers being bad - wrong. What is bad is people not learning about and flying correctly their current type of aircraft. That involves learning about all the differences and special procedures (inc ref etc)
No it was not erroneous - the system operated exactly as it was supposed to.
It was the inability of the crew to correctly fly the aircraft for the conditions they were in.
A lot of talk about stick shake / pushers being bad - wrong. What is bad is people not learning about and flying correctly their current type of aircraft. That involves learning about all the differences and special procedures (inc ref etc)
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Weak Possible Explanation
I was taught the following sequence for stall or incipient stall recovery:
- Nose on horizon
- apply power
- retract flaps when airspeed adequate
It is therefore possible the PF pulled back to get the nose on the horizon. He may have glanced at the PFD and thought he saw nose low (turbulence maybe) and scanned on to other instruments.
I know, its a stretch, but there must have been SOME reason for what he did.
- Nose on horizon
- apply power
- retract flaps when airspeed adequate
It is therefore possible the PF pulled back to get the nose on the horizon. He may have glanced at the PFD and thought he saw nose low (turbulence maybe) and scanned on to other instruments.
I know, its a stretch, but there must have been SOME reason for what he did.
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I watched the specail on Frontline last night about the Colgan crash and "Flying Cheap". And although the program was decent it did not go into detail about what happened. One point that it brought up that was interesting was the fact that the Q400 was new to Colgan and the pilots really didn't understand the aircraft. This was shocking news. How could this be. Is the Q8 that difficult to master? And if so how could they have pilots flying an aircraft with little experience? Shame on Colgan......
Last edited by Razoray; 11th Feb 2010 at 00:36.