Take off with snow on wing
DOVE
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For some reason my thread was deleted. So I will repeat it with some sweetening (and I will save my hard work this time ).
Mr AirRabbit: You’re so pathetic for the ardour with which you are defending the indefensible.
Anyone, with no exception, has the right to an advocacy, but in the trial, not from the trial.
We always say pompously: “to know exactly who or what is at fault for this crash before the plane's black boxes are examined and a full, professional investigation is completed. Let's wait for that to happen before we decide who deserves the blame.”
In this case we know exactly what happened thanks to the NTSB investigation.
All my Quotes (http://www.pprune.org/7151865-post357.html) have been extracted from the NTSB Aicraft Accident Report in spite you ascribe them to me (http://www.pprune.org/7152158-post362.html)
I urge all those who have not yet done so to read the report: Volo Air Florida 90 - Wikipedia http://www.airdisaster.com/reports/ntsb/AAR82-08.pdf
and:
http://www.airdisaster.com/reports/ntsb/AAR82-08.pdf
NTSB Report, page 5 line 25: “Eight seconds after the captain called “Vee one” and 2 seconds after he called “Vee two,” the sound of the stickshaker 91 was recorded.”
1) Did anybody call “Vr”? (Or rotate as US Pilots use to say?)
2) V2 was only 2 knots higher then Vr. And in spite of that they were already airborne (stickshaker activated).
Usually it takes 5 to10 seconds (6”: normal rate beeing 3° per second) to achieve a normal take off attitude of 20°
In science the interpretation of a phenomenon is recognized as a law only if its experience is replicable, otherwise it’s a chimera.
We, therefore, must learn from the mistakes of others in order not to repeat them, and must ignore their fortunes, unrepeatable.
I say in a choir with warmkiter: make it clean and keep it clean
and Rabski: Contamination = no go.
And many others.
You should too shout with me: “HOW CAN YOU KNOW IF ANY KIND OF SNOW IS ‘ADHERING’ TO THE SURFACES OF YOUR AIRPLANE, AND NO ICE IS BENEATH IT, IF YOU DON'T REMOVE IT?”
“No clean aircraft? No Fly!”
Mr AirRabbit: You’re so pathetic for the ardour with which you are defending the indefensible.
Anyone, with no exception, has the right to an advocacy, but in the trial, not from the trial.
We always say pompously: “to know exactly who or what is at fault for this crash before the plane's black boxes are examined and a full, professional investigation is completed. Let's wait for that to happen before we decide who deserves the blame.”
In this case we know exactly what happened thanks to the NTSB investigation.
All my Quotes (http://www.pprune.org/7151865-post357.html) have been extracted from the NTSB Aicraft Accident Report in spite you ascribe them to me (http://www.pprune.org/7152158-post362.html)
I urge all those who have not yet done so to read the report: Volo Air Florida 90 - Wikipedia http://www.airdisaster.com/reports/ntsb/AAR82-08.pdf
and:
http://www.airdisaster.com/reports/ntsb/AAR82-08.pdf
As I indicated to you in my earlier response ... the F/O did NOT begin the rotation “well before Vr. The computed V-speeds (again, for your information) were V1 = 138 knots; Vr = 140 knots; and V2 = 144 knots. The CVR clearly shows the Captain calling out “Vee One.” It was 2 seconds later that the Captain said “Easy!”
1) Did anybody call “Vr”? (Or rotate as US Pilots use to say?)
2) V2 was only 2 knots higher then Vr. And in spite of that they were already airborne (stickshaker activated).
Usually it takes 5 to10 seconds (6”: normal rate beeing 3° per second) to achieve a normal take off attitude of 20°
And as I said the airplane immediately preceding and the airplane immediately following
were both subjected to the same inclement weather that affected the accident airplane.
Yet it was only the accident airplane that crashed.
were both subjected to the same inclement weather that affected the accident airplane.
Yet it was only the accident airplane that crashed.
We, therefore, must learn from the mistakes of others in order not to repeat them, and must ignore their fortunes, unrepeatable.
I say in a choir with warmkiter: make it clean and keep it clean
and Rabski: Contamination = no go.
And many others.
You should too shout with me: “HOW CAN YOU KNOW IF ANY KIND OF SNOW IS ‘ADHERING’ TO THE SURFACES OF YOUR AIRPLANE, AND NO ICE IS BENEATH IT, IF YOU DON'T REMOVE IT?”
“No clean aircraft? No Fly!”
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The Patience I Started With is Waning Quickly
Mr. Doves:
First, I am going to ignore the blatant insult, in the hope that it was only because you cannot understand my position … because of issues you cannot understand or choose to ignore. With all due respect … and, unfortunately, I fear, what is actually due with regard to that respect, is quickly expiring! You claim to know “exactly what happened,” and you cite the singular source for “knowing” all you say you know is that NTSB report … and I would presume, only, that report. The clear error you are making is believing only what you want to believe of that text and ignoring the blatant inconsistencies in that very same text.
Sir, as I believe I’ve said previously, I am fully aware of where you obtained the information you have “quoted” in your posts here. I am also aware, at least I believe, that the English language is not your first language (and if correct, you have my compliments for being as conversant as you are in English – I am conversant only in English – one of the not-so-admirable traits many of us Americans share…) but in that understanding there may be some room for your apparent misunderstanding of what is said in that report.
As merely one example of the confusion I am experiencing … are we who read your posts, to understand that if you do not hear the other pilot in your cockpit actually say out-loud, “Vee R” or “Rotate,” and failing to hear that verbal call-out you would not rotate? If you pass “Vee One” speed, later arriving at “Vee Two” speed … how is it that, in your opinion, you believe that the airplane did not achieve “Vee R” or “rotate” speed? Oh, by the way, one error in your reading of the transcript, sir … is your statements regarding “V2 speed” … the computed, briefed, (and believed set) “Vee Two” speed was actually 144 knots, and that is actually 4 knots higher than “Vee R” speed, which was also computed, briefed (and believed set) at 140 knots – although, admittedly, I’m at a loss to understand the significance you seem to attach to that relationship – whether it was the 4 knots the crew briefed (and most believe) used … or the 2 knots that you state. And NO, it’s not a requirement to call-out “Rotate” – and, while there are certainly some who do, not all flight crews make that call.
I also see that you note it wasn’t long after reaching “Vee Two” speed that the CVR transcript indicates the sound of the “stick shaker” begins. What that CVR transcript does not show is that on the actual recording there were very clear sounds of substantial buffeting – in fact, the buffeting noise was almost distracting to anyone listening to the CVR for the remainder of its recording. The airplane had not merely exceeded the AoA at which the stall warning was to be activated – it also achieved an AoA at least equal to, and very likely well beyond, the critical (stall) AoA – putting the airplane into an aerodynamic stall – from which all the obtrusive buffeting noise was generated.
Interestingly, you say that you are familiar with circumstances where it usually “…takes 5 to10 seconds (as you say "...the normal rate beeing 3° per second") to achieve a normal take off attitude of 20°” My suspicions are that you might be surprised to learn that I completely agree with your statements here … as, I too, am familiar with similar time requirements to rotate from a normal 3-point, ground contact position, to that normal takeoff attitude … although we used 18 degrees as “normal” … I’ll not quarrel with 20 degrees. At 3 degrees per second (a traditionally normal takeoff rotation rate) would take something on the order of 6 to 6 ½ seconds to achieve that normally achieved 18-20-degree attitude. With some of that waning respect I have left, I would question why it is that you choose to disbelieve, or you choose not to apply any relevance to the fact that the airplane rotated from the “3-point ground contact position” all the way to an attitude that exceeded the critical AoA (some witnesses said the pitch attitude was above 40 degrees) in in something on the order of a half to a third of the time it should have taken to rotate to what you describe as a “normal takeoff attitude.” For what it’s worth, you are not alone in that lack of understanding or that disbelief! But it happened. The facts are there. Clearly. It’s evident in the transcript, but those facts – as blatantly incongruous with other facts as they are – they are completely without comment, and are clearly indicative of some other factor that was either overlooked or was not given sufficient consideration, or was (and I do not like saying it) either deliberately or ignorantly suppressed in the deliberations that followed. The question remains … why would a B-737 rotate from a 3-point ground contact position to an attitude that puts the airplane at or beyond the critical AoA into an aerodynamic stall and do so well short of the time it would normally take to rotate only to 18 – 20 degrees? Is there anyone who really believes it was the F/O that “snatched” the airplane to that kind of attitude in that short period of time?? … when he had just stated that he was only going to rotate to get the nose gear into the air and “…just let (the airplane) fly off the ground”?? No one addressed this terribly obvious question. Additionally, after getting airborne, the transcript clearly shows the Captain repeatedly urging the F/O to move the control column “forward” … “come on forward” … “forward” … “just barely climb” … “we only want 500” … “forward.” Why doesn’t anyone question what that conversation was all about – and more importantly – why didn’t the F/O do what the Captain was urging him to do! Why didn’t someone take note of the fact that the Accident Report also includes statements from the airplane manufacturer that clearly shows that there was a “known tendency” for that airplane to “pitch-up” and/or “roll-off” when subjected to very minor amounts of freezing precipitation?? It seems more than just a little strange to me that such a potential was virtually ignored in the report and certainly was ignored in the conclusions reached ... particularly given the level of tragedy that occurred.
So, Mr. Doves … you continue to advocate a choir to sing the mantra that you so fervently desire … I’d just ask that if you’re going to put confidence into a report – that you do so with the ENTIRE report – and not selectively pick and choose portions of the report that seem to match and completely disregard any and all of those points that are horribly outside of any reasonable boundary for what you’ve chosen to believe.
First, I am going to ignore the blatant insult, in the hope that it was only because you cannot understand my position … because of issues you cannot understand or choose to ignore. With all due respect … and, unfortunately, I fear, what is actually due with regard to that respect, is quickly expiring! You claim to know “exactly what happened,” and you cite the singular source for “knowing” all you say you know is that NTSB report … and I would presume, only, that report. The clear error you are making is believing only what you want to believe of that text and ignoring the blatant inconsistencies in that very same text.
Sir, as I believe I’ve said previously, I am fully aware of where you obtained the information you have “quoted” in your posts here. I am also aware, at least I believe, that the English language is not your first language (and if correct, you have my compliments for being as conversant as you are in English – I am conversant only in English – one of the not-so-admirable traits many of us Americans share…) but in that understanding there may be some room for your apparent misunderstanding of what is said in that report.
As merely one example of the confusion I am experiencing … are we who read your posts, to understand that if you do not hear the other pilot in your cockpit actually say out-loud, “Vee R” or “Rotate,” and failing to hear that verbal call-out you would not rotate? If you pass “Vee One” speed, later arriving at “Vee Two” speed … how is it that, in your opinion, you believe that the airplane did not achieve “Vee R” or “rotate” speed? Oh, by the way, one error in your reading of the transcript, sir … is your statements regarding “V2 speed” … the computed, briefed, (and believed set) “Vee Two” speed was actually 144 knots, and that is actually 4 knots higher than “Vee R” speed, which was also computed, briefed (and believed set) at 140 knots – although, admittedly, I’m at a loss to understand the significance you seem to attach to that relationship – whether it was the 4 knots the crew briefed (and most believe) used … or the 2 knots that you state. And NO, it’s not a requirement to call-out “Rotate” – and, while there are certainly some who do, not all flight crews make that call.
I also see that you note it wasn’t long after reaching “Vee Two” speed that the CVR transcript indicates the sound of the “stick shaker” begins. What that CVR transcript does not show is that on the actual recording there were very clear sounds of substantial buffeting – in fact, the buffeting noise was almost distracting to anyone listening to the CVR for the remainder of its recording. The airplane had not merely exceeded the AoA at which the stall warning was to be activated – it also achieved an AoA at least equal to, and very likely well beyond, the critical (stall) AoA – putting the airplane into an aerodynamic stall – from which all the obtrusive buffeting noise was generated.
Interestingly, you say that you are familiar with circumstances where it usually “…takes 5 to10 seconds (as you say "...the normal rate beeing 3° per second") to achieve a normal take off attitude of 20°” My suspicions are that you might be surprised to learn that I completely agree with your statements here … as, I too, am familiar with similar time requirements to rotate from a normal 3-point, ground contact position, to that normal takeoff attitude … although we used 18 degrees as “normal” … I’ll not quarrel with 20 degrees. At 3 degrees per second (a traditionally normal takeoff rotation rate) would take something on the order of 6 to 6 ½ seconds to achieve that normally achieved 18-20-degree attitude. With some of that waning respect I have left, I would question why it is that you choose to disbelieve, or you choose not to apply any relevance to the fact that the airplane rotated from the “3-point ground contact position” all the way to an attitude that exceeded the critical AoA (some witnesses said the pitch attitude was above 40 degrees) in in something on the order of a half to a third of the time it should have taken to rotate to what you describe as a “normal takeoff attitude.” For what it’s worth, you are not alone in that lack of understanding or that disbelief! But it happened. The facts are there. Clearly. It’s evident in the transcript, but those facts – as blatantly incongruous with other facts as they are – they are completely without comment, and are clearly indicative of some other factor that was either overlooked or was not given sufficient consideration, or was (and I do not like saying it) either deliberately or ignorantly suppressed in the deliberations that followed. The question remains … why would a B-737 rotate from a 3-point ground contact position to an attitude that puts the airplane at or beyond the critical AoA into an aerodynamic stall and do so well short of the time it would normally take to rotate only to 18 – 20 degrees? Is there anyone who really believes it was the F/O that “snatched” the airplane to that kind of attitude in that short period of time?? … when he had just stated that he was only going to rotate to get the nose gear into the air and “…just let (the airplane) fly off the ground”?? No one addressed this terribly obvious question. Additionally, after getting airborne, the transcript clearly shows the Captain repeatedly urging the F/O to move the control column “forward” … “come on forward” … “forward” … “just barely climb” … “we only want 500” … “forward.” Why doesn’t anyone question what that conversation was all about – and more importantly – why didn’t the F/O do what the Captain was urging him to do! Why didn’t someone take note of the fact that the Accident Report also includes statements from the airplane manufacturer that clearly shows that there was a “known tendency” for that airplane to “pitch-up” and/or “roll-off” when subjected to very minor amounts of freezing precipitation?? It seems more than just a little strange to me that such a potential was virtually ignored in the report and certainly was ignored in the conclusions reached ... particularly given the level of tragedy that occurred.
So, Mr. Doves … you continue to advocate a choir to sing the mantra that you so fervently desire … I’d just ask that if you’re going to put confidence into a report – that you do so with the ENTIRE report – and not selectively pick and choose portions of the report that seem to match and completely disregard any and all of those points that are horribly outside of any reasonable boundary for what you’ve chosen to believe.
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I'm curious.. It's well known contamination can increase the stalling speed but would the stick shaker also operate at a higher airspeed? How does the stall warning sensor know there is contamination or is it only looking at air speed and AOA?
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Just beating your head
Relax AirRabbit, you're never going to get through to those "holier than thou" who live in a more perfect world than ours. Just know that there are those of us who do get what you are saying--that deicing procedures & culture at that time & place were much less precise than now, there was no stated holdover time, & the cockpit crew knew that if they went back for another deice that they would encounter the same or worse delay for takeoff. We understand your very plausible theory that the airplane was thoroughly ICED by faulty deicing procedures which made it unflyable due to a sudden uncontrollable pitch-up at the point of rotation. We also understand that many of the contributing facts you mention were not included or were glossed over in the NTSB report.Thank you for your very knowledgeable input.
Our esteemed PPRuNe colleague seems to share another trait with the legendary captain Dudley: persistence. While obvious t-person is obvious, his marveling on application of the second Newton's law on the frozen 737 racing down the runway with too low thrust (How did he achieve the V2? - See NTSB report, findings, #20) shows where many a debate here takes a wrong turn; folks with feeble grasp of elementary physics, building up advanced aerodynamic theories on flawed basic notions.
Connets has made an interesting point:
What is very well known to psychologists, penal law experts and sociologists but is cheerfully ignored by lawmakers and general public is that high chance of getting caught is far more powerful deterrent than severe punishment. It neatly explains people being pick-pocketed while watching the execution of pickpockets in Dickensian England or numerous executions for graft in country I shall not name due to political correctness.
Considering the laws of aerodynamics, that Mother Nature applies with absolute impartiality while showing no mercy, this observation might help to explain why-oh-why pilots keep on taking off with snowy or iced over wings. Possible punishment is capital, yet the chances that it will be meted out are slim. The snow might indeed slip off the wings and anything still clinging on as the aeroplane climbs out of ground effect is usually not enough to completely reduce the lift to the point below the weight. Afterwards, as ice melts, there's no way to tell whether the disaster was averted by a knot, five or ten and ignoramuses in cockpit go very long way to prove their experiment was both safe and legal. I find definition of take-off as being only the actual liftoff quite amusing, taken in combination with the big red warning at the bottom of the page.
However, I have seen far too many successful takeoffs with snow on the wings in the real life to kid myself with the notion that anyone advocating laissez-fair approach to ice is really an impostor. Seemingly, some Russians are not the only one susceptible to the malaise of ignorance. Or Spaniards. Or LoCo drivers. Or third world pilots. That fellow next to you might be infected too.
No, unless aeroplane has modified stall warning threshold when operating anti ice devices, e.g. automatically with selection of flight controls horn heating (I forgot exactly which one) on ATR or manually selected on DHC-8. No such thing on A320 and I never heard about it on B737.
Connets has made an interesting point:
Originally Posted by Connets
During my working years as an academic, I realised that we don't always ask what, precisely, we hope to acheive by the use of the penal sanction (and I include internal disciplinary proceedings). I would have thought that here it is not to exact vengeance, but to prevent the harm from happening.
Considering the laws of aerodynamics, that Mother Nature applies with absolute impartiality while showing no mercy, this observation might help to explain why-oh-why pilots keep on taking off with snowy or iced over wings. Possible punishment is capital, yet the chances that it will be meted out are slim. The snow might indeed slip off the wings and anything still clinging on as the aeroplane climbs out of ground effect is usually not enough to completely reduce the lift to the point below the weight. Afterwards, as ice melts, there's no way to tell whether the disaster was averted by a knot, five or ten and ignoramuses in cockpit go very long way to prove their experiment was both safe and legal. I find definition of take-off as being only the actual liftoff quite amusing, taken in combination with the big red warning at the bottom of the page.
However, I have seen far too many successful takeoffs with snow on the wings in the real life to kid myself with the notion that anyone advocating laissez-fair approach to ice is really an impostor. Seemingly, some Russians are not the only one susceptible to the malaise of ignorance. Or Spaniards. Or LoCo drivers. Or third world pilots. That fellow next to you might be infected too.
I'm curious.. It's well known contamination can increase the stalling speed but would the stick shaker also operate at a higher airspeed?
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Actually that sort of makes AirRabbit's point, since the AOA vane only reads angle of airflow. If the airplane was rotated normally with the wing stalled at a lower than normal AOA due to ice affect, there would only be buffet sounds on the CVR. The stick shaker would not have activated.
Controversial, moi?
We will never know but AirRabbit's calm and persistent statements do make me inclined to believe that what he says may well be the reality of what caused the accident that fateful day.
The 'pitch up, roll off' characteristic of the B737 was well known. BA had a serious incident caused by this very phenomenon on take off out of Helsinki on a B737-200. It directly led to an increased speed procedure (possibly unique to BA), whose details I forget, in given conditions. The training captain who completed my training on the B737 was the co-pilot on the incident flight out of Helsinki and his description of the event when he related it to me in 1989 was as vivid and scary as it was when it occurred many years earlier.
The 'pitch up, roll off' characteristic of the B737 was well known. BA had a serious incident caused by this very phenomenon on take off out of Helsinki on a B737-200. It directly led to an increased speed procedure (possibly unique to BA), whose details I forget, in given conditions. The training captain who completed my training on the B737 was the co-pilot on the incident flight out of Helsinki and his description of the event when he related it to me in 1989 was as vivid and scary as it was when it occurred many years earlier.
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Originally Posted by Clandestino
Our esteemed PPRuNe colleague seems to share another trait with the legendary captain Dudley: persistence. While obvious t-person is obvious, his marveling on application of the second Newton's law on the frozen 737 racing down the runway with too low thrust (How did he achieve the V2? - See NTSB report, findings, #20) shows where many a debate here takes a wrong turn; folks with feeble grasp of elementary physics, building up advanced aerodynamic theories on flawed basic notions.
Considering the laws of aerodynamics, that Mother Nature applies with absolute impartiality while showing no mercy….
Considering the laws of aerodynamics, that Mother Nature applies with absolute impartiality while showing no mercy….
Oh wait, wait … I think I’ve got it … perhaps Clandestino wants all of us to understand that when you have a group of “psychologists” who engage in a debate on penal law while attempting to rush a “frozen 737” down a runway, if they use “too low thrust” they just may “take a wrong turn” and have to appeal to Mother Nature, who will, as he correctly points out, meet out her decisions, “…with absolute impartiality while showing no mercy.” Or .... well ... maybe not.
DOVE
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Mr AirRabbit
I am sorry that you have interpreted as a blatant insult the adjective “pathetic”.
The semiotic origin of the word is:
Pathos; plural: patha or pathea; Greek: πάθος, for "suffering" or "experience;" adjectival form: 'pathetic' from παθητικός) represents an appeal to the audience's emotions. Pathos is a communication technique used most often in rhetoric (where it is considered one of the three modes of persuasion, alongside ethos and logos).
Is there anything hurting someone’s feelings? On the contrary!
It has already been noticed that I'm not very familiar with the English language, that’s why I didn’t struggle to choose the most appropriate word to express the feelings given to me by your stubbornness in defending the actions of the pilots of Air Florida Flight 90, of January 13, 1982.
I do not know what’s the reason why you do so.
I can tell you that my ethical and logical motivation is that I am sick and tired of hearing and reading about plane crashes (which, thanks to God I am avoiding since more than 45 years) due to "Pilot error". And if I cannot save the world, all I need to know is that I gave someone a bit of my experience thus making him spare his aircraft and a number of lives.
I cannot be in an ailiner’s cockpit anymore to deice when needed, but I swear that I will claim, as a SLF, the airplane to be de-icede/anti-iced if I find myself in a situation like:
http://www.pprune.org/7127125-post1.html
And like Plutarch used to write at the end of a treaty.
On this subject it’s enough.
I am sorry that you have interpreted as a blatant insult the adjective “pathetic”.
The semiotic origin of the word is:
Pathos; plural: patha or pathea; Greek: πάθος, for "suffering" or "experience;" adjectival form: 'pathetic' from παθητικός) represents an appeal to the audience's emotions. Pathos is a communication technique used most often in rhetoric (where it is considered one of the three modes of persuasion, alongside ethos and logos).
Is there anything hurting someone’s feelings? On the contrary!
It has already been noticed that I'm not very familiar with the English language, that’s why I didn’t struggle to choose the most appropriate word to express the feelings given to me by your stubbornness in defending the actions of the pilots of Air Florida Flight 90, of January 13, 1982.
I do not know what’s the reason why you do so.
I can tell you that my ethical and logical motivation is that I am sick and tired of hearing and reading about plane crashes (which, thanks to God I am avoiding since more than 45 years) due to "Pilot error". And if I cannot save the world, all I need to know is that I gave someone a bit of my experience thus making him spare his aircraft and a number of lives.
I cannot be in an ailiner’s cockpit anymore to deice when needed, but I swear that I will claim, as a SLF, the airplane to be de-icede/anti-iced if I find myself in a situation like:
http://www.pprune.org/7127125-post1.html
And like Plutarch used to write at the end of a treaty.
On this subject it’s enough.
Last edited by DOVES; 26th Apr 2012 at 19:32.
Originally Posted by M. Mouse
We will never know
Originally Posted by M. Mouse
calm and persistent statements do make me inclined to believe that what he says may well be the reality of what caused the accident that fateful day.
Originally Posted by The National Safety Transportation Board
The National Transportation Safety Board determines that the probable cause
of this accident was the flightcrew’s failure to use engine anti-ice during ground operation
and takeoff, their decision to take off with snow/ice on the airfoil surfaces of the
aircraft, and the captain’s failure to reject the takeoff during the early stage when his
attention was called to anomalous engine instrument readings. Contributing to the
accident were the prolonged ground delay between deicing and the receipt of ATC takeoff
clearance during which the airplane was exposed to continual precipitation, the known
inherent pitchup characteristics of the B-737 aircraft when the leading edge is
contaminated with even small amounts of snow or ice, and the limited experience of the
- flightcrew in jet transport winter operations.
Originally Posted by cwattters
I'm curious.. It's well known contamination can increase the stalling speed but would the stick shaker also operate at a higher airspeed? How does the stall warning sensor know there is contamination or is it only looking at air speed and AOA?
Originally Posted by NTSB report AAR82-08
Most air carrier aircraft are equipped with a stickshaker or some other type of
alarm to alert the pilot that his aircraft is approaching the stall angle of attack. In the
B-737, the stickshaker is activated when a fuselage-mounted vane aligns itself with the
airflow and reaches a preset angle of attack which is less than the stall angle of attack.
The normal alarm margin is equivalent to about 10 percent of the stall airspeed. Since
the stall warning activation is independent of the actual airflow conditions on the wing,
the angle of attack at which it will activate is not affected by snow or ice contamination
on the wing. However, if the wing’s lift-producing efficiency is reduced by such
contamination, the aircraft will be maintaining a higher than normal airspeed when flown
at the angle of attack at which the stickshaker will activate in order to compensate for
the degraded efficiency of the wing.
Thus, the stickshaker will activate at a higher-than-normal airspeed.
Furthermore, the angle of attack margin, and thus the airspeed margin, between
stall warning, stall buffet, and stall will be reduced significantly
or negated entirely.
Controversial, moi?
You should read the report.
They were the official reports so we must unquestioningly accept them, I agree.
You are agreeing with whom? Who said/wrote that official reports have to be accepted unquestioningly?
If there is a conclusion in the report, there must be a method described which led to it. This method has to be scrutable and found to be valid. Otherwise, it's not a report but rather a pamphlet.
Science is not a cult! It is not scientific if scientist says so. It is scientific if it is open to independent validation and confirmation (or disproving, if you're into Popper)
If there is a conclusion in the report, there must be a method described which led to it. This method has to be scrutable and found to be valid. Otherwise, it's not a report but rather a pamphlet.
Science is not a cult! It is not scientific if scientist says so. It is scientific if it is open to independent validation and confirmation (or disproving, if you're into Popper)
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In an earlier post, I said that ”…my motive in saying what I’m saying (and what I’ve said previously), is in no way intending to impugn the fine reputation or the integrity of the NTSB or of the dedicated and professional employees at the Safety Board.”
…and you respond with ”There you have it! It not just their integrity, dedication and professionalism that counts, it is their expertize laid open in their reports for all world to see and discuss.”
..and that is all I am doing. Taking their integrity, dedication, and professionalism … and discussing the conclusions they reached… which are the following.
The National Transportation Safety Board determines that:
The probable cause of this accident was
1) the flightcrew’s failure to use engine anti-ice during ground operation and takeoff,
2) their decision to take off with snow/ice on the airfoil surfaces of the aircraft, and
3) the captain’s failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings.
Contributing to the accident were
1) the prolonged ground delay between deicing and the receipt of ATC takeoff clearance during which the airplane was exposed to continual precipitation,
2) the known inherent pitchup characteristics of the B-737 aircraft when the leading edge is contaminated with even small amounts of snow or ice, and
3) the limited experience of the - flightcrew in jet transport winter operations.
Probable Causes … one at a time:
1. “…the flightcrew’s failure to use engine anti-ice during ground operation and takeoff…”
Just the other day, one of the PPRuNe Forum participants, J.O. posted the following:
Clearly, this person must also have the same level of integrity, dedication, and professionalism as other members of the NTSB investigation team … right? Well … where was this person’s comments in the report? Selective editing? Comments are inserted on the basis of what … votes?
2. “…their decision to take off with snow/ice on the airfoil surfaces of the aircraft…”
While I know some will cringe once again – but facts are facts … there were other airplanes in that same takeoff line – exposed to exactly the same snow fall as the accident airplane was exposed … why the difference? You all know what I’m going to say … the difference was that no other airplane that day was deiced / anti-iced by the same deicing vehicle that deiced that accident airplane. Where was that comment in the report?
3. “…the captain’s failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings.”
This is another path we’ve been down several times. I’ve always wondered why it was that the NTSB was under the impression that the Captain’s attention was called to “anomalous engine instrument readings.” The F/O is the one who was asking questions. Did he say anything about the engines? No. He was rather vocal about something … no doubt. But he also seemed to be vacillating between questioning something and believing everything was OK. This issue was going on for quite a while – something like 20 seconds or so. Yet, nothing conclusive was ever said - and the engines were not mentioned. The interesting note here is that when the F/O made what I would call his first “declaration” and no longer questioning, when he said “Ah, that’s not right.” That’s not a question. But it was that F/O who 2 seconds later, apparently satisfied himself … he said “(Well”). Two seconds later the Captain said “Yes it is. There’s eighty.” A quick question for you aviators out there. Where was the accident airplane when the Captain said “Yes it is. There’s eighty”? How far down the runway do you get when your airplane gets to "eighty knots?" I ask because a scant 2 seconds later, the B-727 landing behind them called “Fourteen fifty-one cleared to land - over the lights.” Where was this B-727? Where was the accident airplane? If you were the Captain … would you have said “I’ve got the airplane” … taken over the controls … and the F/O would have to release control of the airplane (primarily getting his feet off of the rudder pedals). The Captain would then have gone through the abort procedures … bringing the throttles to idle smartly … and then into reverse, while applying as much toe brakes as he could muster … keeping the control column firmly forward (not too much) so that the nose gear would be firmly on the ground through all that ice and snow on the runway … maintain rudder pedal steering down the runway … while the F/O would have grabbed the microphone, raised it to his mouth and said something like “Palm 90 … aborting on the runway!” Where would that B-727 have been at THAT time? Again, I ask, if you were the Captain, knowing what that Captain knew, would you have aborted? I know a lot of folks who answered “yes” and a lot who answered “no.”
Contributing Causes … one at a time:
1. “…the prolonged ground delay between deicing and the receipt of ATC takeoff clearance during which the airplane was exposed to continual precipitation…”
Guess what gang … same response as provided in #2, above … there were other airplanes in that same takeoff line – exposed to exactly the same snow fall as the accident airplane was exposed … why the difference? Same answer … again … You all know what I’m going to say … the difference was that no other airplane that day was deiced / anti-iced by the same deicing vehicle that deiced that accident airplane. Where was that comment in the report?
2. “…the known inherent pitchup characteristics of the B-737 aircraft when the leading edge is contaminated with even small amounts of snow or ice…”
Whoa there folks! What is this? A characteristic of the airplane to pitch up – without any input from the crew? When would this happen? Oh … when there were “even small amounts of snow or ice” on the leading edge of the wing? Well … THIS could be really significant … right? Well, no actually … the NTSB decided that this was merely a contributing factor … not a “cause” of the accident. Really? I mean … really!?
Again, just the other day, another one of the PPRuNe Forum participants, this time it was M.Mouse posted the following:
Hmm … another “serious” incident … the NTSB had no interest in this or any other information about similar circumstances … even though they acknowledge – right there in the report – that this airplane type is KNOWN to do this? And it’s not significant enough to look any further? Really! Really?
3. “…the limited experience of the flightcrew in jet transport winter operations…”
This is easily one of the most questionable comments in the entire report. First, let’s look at what NTSB says about their experience. The report says the following:
Hmm… sounds pretty skinny … right? Let me ask a question of each pilot out there. Do you remember your first takeoff in ice or snow conditions? How experienced were you in making that kind of takeoff? How much experience should be required of pilots in making takeoffs in ice and snow before we should let them make takeoffs in ice and snow? Did the NTSB examine what the Captain and F/O did for a living before coming to work at Air Florida? Would that … could that have been an important issue? Don’t know about you … but I do. Unfortunately, I don’t know what the Captain had done in his years of flying prior to working at Air Florida … and I wonder if he had made any takeoffs or landings in ice and snow when he was a First Officer for Air Florida. Would that have made an interesting fact? Hmm… What was the F/O doing prior to coming to work at Air Florida? Well, he was an all-weather fighter/interceptor pilot, flying F-15’s, out of Minot, North Dakota. Hmm … probably not much ice or snow in Minot, North Dakota … right? (Shessh)
So ... we've had the "official" NTSB Accident Report for almost 30 years now. Will anything I say cause anything in that report to be changed ... no, certainly no. Does that mean that everything they said in that report is accurate and complete ... same answer ... no, certainly no. Why bring it up? Simple answer (not chacteristic of me but...) because I think the truth deserves its time in the light.
…and you respond with ”There you have it! It not just their integrity, dedication and professionalism that counts, it is their expertize laid open in their reports for all world to see and discuss.”
..and that is all I am doing. Taking their integrity, dedication, and professionalism … and discussing the conclusions they reached… which are the following.
The National Transportation Safety Board determines that:
The probable cause of this accident was
1) the flightcrew’s failure to use engine anti-ice during ground operation and takeoff,
2) their decision to take off with snow/ice on the airfoil surfaces of the aircraft, and
3) the captain’s failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings.
Contributing to the accident were
1) the prolonged ground delay between deicing and the receipt of ATC takeoff clearance during which the airplane was exposed to continual precipitation,
2) the known inherent pitchup characteristics of the B-737 aircraft when the leading edge is contaminated with even small amounts of snow or ice, and
3) the limited experience of the - flightcrew in jet transport winter operations.
Probable Causes … one at a time:
1. “…the flightcrew’s failure to use engine anti-ice during ground operation and takeoff…”
Just the other day, one of the PPRuNe Forum participants, J.O. posted the following:
Many years ago I met a member of the NTSB team that investigated Palm 90. I asked him if he believed that the accident would have been avoided if the crew had applied full thrust. His response was that if they'd have had full thrust, all it would have done was make an unflyable airplane unflyable a little bit sooner.
2. “…their decision to take off with snow/ice on the airfoil surfaces of the aircraft…”
While I know some will cringe once again – but facts are facts … there were other airplanes in that same takeoff line – exposed to exactly the same snow fall as the accident airplane was exposed … why the difference? You all know what I’m going to say … the difference was that no other airplane that day was deiced / anti-iced by the same deicing vehicle that deiced that accident airplane. Where was that comment in the report?
3. “…the captain’s failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings.”
This is another path we’ve been down several times. I’ve always wondered why it was that the NTSB was under the impression that the Captain’s attention was called to “anomalous engine instrument readings.” The F/O is the one who was asking questions. Did he say anything about the engines? No. He was rather vocal about something … no doubt. But he also seemed to be vacillating between questioning something and believing everything was OK. This issue was going on for quite a while – something like 20 seconds or so. Yet, nothing conclusive was ever said - and the engines were not mentioned. The interesting note here is that when the F/O made what I would call his first “declaration” and no longer questioning, when he said “Ah, that’s not right.” That’s not a question. But it was that F/O who 2 seconds later, apparently satisfied himself … he said “(Well”). Two seconds later the Captain said “Yes it is. There’s eighty.” A quick question for you aviators out there. Where was the accident airplane when the Captain said “Yes it is. There’s eighty”? How far down the runway do you get when your airplane gets to "eighty knots?" I ask because a scant 2 seconds later, the B-727 landing behind them called “Fourteen fifty-one cleared to land - over the lights.” Where was this B-727? Where was the accident airplane? If you were the Captain … would you have said “I’ve got the airplane” … taken over the controls … and the F/O would have to release control of the airplane (primarily getting his feet off of the rudder pedals). The Captain would then have gone through the abort procedures … bringing the throttles to idle smartly … and then into reverse, while applying as much toe brakes as he could muster … keeping the control column firmly forward (not too much) so that the nose gear would be firmly on the ground through all that ice and snow on the runway … maintain rudder pedal steering down the runway … while the F/O would have grabbed the microphone, raised it to his mouth and said something like “Palm 90 … aborting on the runway!” Where would that B-727 have been at THAT time? Again, I ask, if you were the Captain, knowing what that Captain knew, would you have aborted? I know a lot of folks who answered “yes” and a lot who answered “no.”
Contributing Causes … one at a time:
1. “…the prolonged ground delay between deicing and the receipt of ATC takeoff clearance during which the airplane was exposed to continual precipitation…”
Guess what gang … same response as provided in #2, above … there were other airplanes in that same takeoff line – exposed to exactly the same snow fall as the accident airplane was exposed … why the difference? Same answer … again … You all know what I’m going to say … the difference was that no other airplane that day was deiced / anti-iced by the same deicing vehicle that deiced that accident airplane. Where was that comment in the report?
2. “…the known inherent pitchup characteristics of the B-737 aircraft when the leading edge is contaminated with even small amounts of snow or ice…”
Whoa there folks! What is this? A characteristic of the airplane to pitch up – without any input from the crew? When would this happen? Oh … when there were “even small amounts of snow or ice” on the leading edge of the wing? Well … THIS could be really significant … right? Well, no actually … the NTSB decided that this was merely a contributing factor … not a “cause” of the accident. Really? I mean … really!?
Again, just the other day, another one of the PPRuNe Forum participants, this time it was M.Mouse posted the following:
The 'pitch up, roll off' characteristic of the B737 was well known. BA had a serious incident caused by this very phenomenon on take off out of Helsinki on a B737-200. It directly led to an increased speed procedure (possibly unique to BA), whose details I forget, in given conditions. The training captain who completed my training on the B737 was the co-pilot on the incident flight out of Helsinki and his description of the event when he related it to me in 1989 was as vivid and scary as it was when it occurred many years earlier.
3. “…the limited experience of the flightcrew in jet transport winter operations…”
This is easily one of the most questionable comments in the entire report. First, let’s look at what NTSB says about their experience. The report says the following:
The Safety Board reviewed the winter operations conducted by the captain and first officer and found that the captain, after upgrading to captain in B-737 aircraft, had flown eight takeoffs or landings in which precipitation and freezing or near-freezing conditions occurred, and that the first officer had flown two takeoffs or landings in such conditions during his employment with Air Florida, Inc.
So ... we've had the "official" NTSB Accident Report for almost 30 years now. Will anything I say cause anything in that report to be changed ... no, certainly no. Does that mean that everything they said in that report is accurate and complete ... same answer ... no, certainly no. Why bring it up? Simple answer (not chacteristic of me but...) because I think the truth deserves its time in the light.
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Hmm… sounds pretty skinny … right? Let me ask a question of each pilot out there. Do you remember your first takeoff in ice or snow conditions? How experienced were you in making that kind of takeoff? How much experience should be required of pilots in making takeoffs in ice and snow before we should let them make takeoffs in ice and snow?
Every qualified airline captain should be able to read and do procedures laid down in their company FCOM during winter operations.
No need to be Einstein,just be able to read and follow the steps.
Now some captains who have a poor self discipline will tend to disregard standard AND supplementary procedures and this with a lack of winter ops has the potential to end up very badly indeed.
The skills needed to take off on a contaminated runway is purely based on experience/skills and therefore a new pilot in winter ops may have some problems in controlling the aircaft properly and/or during a reject if the case but should not be a danger in itself.
Company SOPs though normally have wind limitations for different level of contamination.
To make a long story short,even a baboon could follow the steps for a successful winter ops take off.
SELF DISCIPLINE is the lacking factor in most cases.
Last edited by de facto; 27th Apr 2012 at 11:06.
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Thread drift - BIG time....................
I’m surprised the moderator(s) have not moved this extensive and ongoing discussion of Air Florida-Palm 90 in Washington DC somewhere else as it has just about completely eclipsed the original post and direction of the thread discussing a recent takeoff with contaminated surfaces.
AirRabbit who obviously has an extensive knowledge base of the facts surrounding Palm 90 in DC, perhaps even worked for the operator or knew those directly involved, presents his position in great detail and with tremendous patience. Perhaps this discussion of the accident deserves its own thread.
With no disrespect to the dead, I am not interested in opening up a new investigation of that accident on this thread.
Let’s see if I understand AirRabbit’s point. It was not snow on the wing that doomed Palm 90, the aircraft had been deiced imperfectly and the wing was covered with ice as it rolled down the departure runway. The 737 pitches up with even a small amount of ice or contamination on the wing, a point that needs to be better understood. What doomed Air Florida was the 737’s pitch up tendency with a contaminated wing of the 737 design combined with ice that was present due to the method and equipment used to “deice” that jet on that day. The accident was not primarily caused by snow accumulation combined with the poor flight crew performance.
So, trying to summarize the multiple posts regarding Air Florida and applying them to the video on the original post I come up with the following. Contamination of any sort on the wing of a commercial T Category jet transport has the potential of rendering the wing incapable of safe flight. Therefore it should be removed prior to flight.
That puts us back to the “clean wing” concept right? Therefore the takeoff video clip that opened up this thread was a dangerous act and an expample of poor airmanship and decision making.
AirRabbit who obviously has an extensive knowledge base of the facts surrounding Palm 90 in DC, perhaps even worked for the operator or knew those directly involved, presents his position in great detail and with tremendous patience. Perhaps this discussion of the accident deserves its own thread.
With no disrespect to the dead, I am not interested in opening up a new investigation of that accident on this thread.
Let’s see if I understand AirRabbit’s point. It was not snow on the wing that doomed Palm 90, the aircraft had been deiced imperfectly and the wing was covered with ice as it rolled down the departure runway. The 737 pitches up with even a small amount of ice or contamination on the wing, a point that needs to be better understood. What doomed Air Florida was the 737’s pitch up tendency with a contaminated wing of the 737 design combined with ice that was present due to the method and equipment used to “deice” that jet on that day. The accident was not primarily caused by snow accumulation combined with the poor flight crew performance.
So, trying to summarize the multiple posts regarding Air Florida and applying them to the video on the original post I come up with the following. Contamination of any sort on the wing of a commercial T Category jet transport has the potential of rendering the wing incapable of safe flight. Therefore it should be removed prior to flight.
That puts us back to the “clean wing” concept right? Therefore the takeoff video clip that opened up this thread was a dangerous act and an expample of poor airmanship and decision making.
Last edited by Northbeach; 27th Apr 2012 at 21:34.
AirRabbit
It’s a shame that the crew of that accident airplane in January of 1982 were not aware of the kinds of things regarding airplane operations in icing conditions you listed. However, I would point out, for your careful consideration that most (if not ALL) of this information, these recommended practices, and these scientifically derived experimentation results you just provided were gained a result of the examinations, experimentations, arguments, discussions, decisions, and considerations conducted because there wasn’t sufficient information on these issues very readily apparent, or even available, prior to this accident?
It’s a shame that the crew of that accident airplane in January of 1982 were not aware of the kinds of things regarding airplane operations in icing conditions you listed. However, I would point out, for your careful consideration that most (if not ALL) of this information, these recommended practices, and these scientifically derived experimentation results you just provided were gained a result of the examinations, experimentations, arguments, discussions, decisions, and considerations conducted because there wasn’t sufficient information on these issues very readily apparent, or even available, prior to this accident?
Air Rabbit quote;.. but, at the same time, if the wing must be absolutely clear of any accumulation of snow (to see that there is absolutely no ice adhering) wouldn’t that effectively eliminate any takeoff during a snow shower? Is that acceptable to the myriad of operations that take place daily in locations where snow appears during winter operations?.
It's true 1982 crews didn't have those A/I fluids we enjoy now, relying only de-ice fluid with some assumed (but vague) anti-ice properties when applied as an aftercoat/overspray. That being said, I'll re-quote the main point I did make pertaining to what was known back in 1982..
..and it was already loud and clear that frost, ice, or snow on the wings during takeoff could kill you. At least in my neck of the woods where it was lousy with all 3. It was certainly widely disseminated aviation knowledge, but I realize that doesn't preclude pilots out there making up their own theories that become culture within fenced-off circles, those within convincing themselves it's routine thinking; "This type of wing handles it", "That'll slide off I've seen it before".
1. FAA regulations. From the report: "The Federal Aviation Regulations are very specific, requiring that "no person may take off an aircraft when frost snow or ice is adhering to the wings, control surfaces, or propellers of the aircraft." The crew knew they had a contaminated wing with frozen precip adhering, yet they took-off it anyway. The Captain made light of the Regs, and yet it's one clearly written in blood long before 1982. Ignorance?..when he said "satisfying the Feds" was he speaking of the act of de-icing but not know that no adhering frost, ice, or snow was the requirement? Or was it feigned, know-it-all parroting of something he'd heard from someone else equally out of their depth. Either way, when they got to the runway they were required to not attempt a takeoff.
2. The Air Florida company Ops Manual mirrored that same Reg, but with relief granted for dry snow if the Captain and person releasing the aircraft agreed conditions precluded adhering. That relief was never sought, and the mod-heavy wet snowy conditions weren't of that nature anyway. So with regards to "clean wing"/contamination", there's no question the crew didn't follow their own Ops Manual either as it existed in 1982. Ignorance of his own Manual?..or disregard for it.
3. Inspection after de-icing. From the Report: "Neither the Air Florida maintenance representative who should have been responsible for proper accomplishment of the deicing/anti-icing operation, nor the captain of Flight 90, who was responsible for assuring that the aircraft was free from snow or ice at dispatch, verified that the aircraft was free of snow or ice contamination before pushback. Ignorance of his own Manual? or disregard for it.
4. Use of reversers. The Air Florida Ops Manual at that time also included Bulletins warning of possible clear ice formation on leading edge devices while using reversers on the ground with snow present. There were also a series of Bulletins and avisories regarding rotation/pitch and roll issues with contamination on the leading edges, and recommended procedures for takeoffs into icing conditions or where contamination may be present. The Captain used the reversers for 30 to 90 seconds at the gate, after de-icing. Ignorance of his own Manual? or disregard for it.
At almost every step where compliance to Air Florida Ops Manual or Regs re winter ops was required there is nothing on the CVR or actions witnessed to indicate the crew was even aware of these requirements, let alone adhered to them. Their actions of using reverse within the confined spaces next to concourse and jetbridge after de-icing was applied, and later trying to position thier aircraft behind Apple's jet blast during taxi to try and melt snow on their own wing, would degrade the minimul anti-ice properties of the de-ice fluid even if that fluid was correctly mixed. These combined, non-approved actions could easily create conditions for ice to form, and this was known information. The F/Os declaration about only needing the inboard portions clean because "with the sweep the rest will slide off after 80" is based on...who knows where he heard that. The Captain's lassaize-faire, non-answer to the F/Os question if there was "anything special" to do for takeoff on that contaminated runway into heavy snow/icing conditions resulting in the F/Os deciding on a "soft field takeoff" solution when there were actual published procedures in their Ops Manual for that situation is another example of apparent ignorance or disregard to applicable procedures.
I mention all this to re-iterate that this crew, on that day and in those particular adverse conditions was virtual green on green. The Captain's experience in bona-fide, winter weather was virtually nonexistant. His previous company, where he had been knocking around south Florida in DC-3s, had been aquired by Air Florida only a few years prior and upgrades were fast. The F/Os commercial aircraft experience in winter ops was even less than the Captains, and his F-15 experience is of dubious relevance..it can fly with an entire wing missing. He exhibited this inexperience by deferring to the Captain's assurances, assurances based on nothing.
Between them there was a big, fat lack-of-experience cheesehole on an unforgiving, wintery day, and in that situation it's critical and incumbent upon any crew to recognize their own limitations and act accordingly. "Accordingly" means conservatively, screwing your flying head down even tighter, and when experience can't guide you the final backstop for safety is strict adherance to Regulation, Manual/SOPs, and applicable recommended procedures for the your specific aircraft. This crew did NONE of those things when faced with conditions unfamiliar to them. They didn't even talk about seeking guidance, and this certainly wasn't one of those rare instances where saving an aircraft means rightfully throwing the Book out. They never had their 1982 Book IN to begin with.
The record shows some of the Captain's proficiency checks went poorly (and failed) due to trouble with the Regs, procedures, systems, and even Limitations of his own aircraft, which is hard to fathom for a new Captain who's nose should be in the books. Those are study-and-preparation issues, and perhaps those subject deficiencies had been rectified, but there's nothing in the Report or CVR to indicate he had prepared himself to gain a working knowledge of his own Air Florida manuals with regards to winter ops, and we heard how seriously he took the regs regarding contamination. Given the series of omissions, non-adherence to Company Policy, and examples of doing things that were known, potential detriments to safety I find it hard to believe the Captain was even aware his Ops Manual contained applicable things he needed to comply with.
"Just to make the Feds happy", "You just need the inboard clear", notions about wing-sweep as it affects shedding..neither of them challenged the other when voicing left-field ideas in areas neither was versed, let alone well-versed in. On the contrary, in both omission and action both exhibited feigned confidence on matters with no experience to draw from, sounding instead like fair-weather pilots revisiting myths told around a Florida crew room campfire back home. The same type of false assurance was exhibited again by the Captain during slow T/O acceleration on a runway aleady accumulating more snow when the F/O raised doubts about it 4 times after mentioning funky engine indications during taxi. Regardless of why it was degraded acceleration, the last chance for the blind to stop leading the blind through a minefield and stopping the show was lost.
You can argue that the de-icing was really icing due to dissimilar mixes and a bad nozzle and that's what caused this accident, it was known that reversers on the ground could cause leading edge contamination, not to mention that swirling your own engine exhaust in the confines next to a concourse and jet bridge would degrade even correctly-mixed de-icing fluid's anti-ice properties or overspray coat. Purposely placing your aircraft into another's jet blast attempting to melt snow accumulations would also ruin any anti-ce properties, and worse, create conditions for re-freezing. Why didn't other aircraft experience the same fate? Those other crews probably weren't using those non-approved procedures or making up their own on the way to the runway that made the situation worse.
You make decent enough arguments on a few points, food for thought anway, but wrapping them in a suggestion that this crew's actions and words represent anything like a barometer of "what was known", done, and disseminated (including to them) re winter ops/contamination/ etc 1982 is a gross misrepresentation. This crew was nothing of the kind, and you whitewashing this crew's inexperience and non-compliance for the sake of focusing on the de-icing issue hints of an agenda.
They were not idiots in the medical sense but that they were ignoramuses is beyond doubt.
How could pilots be so ignorant to perform such a hazardous act ? IMHO, first: they have to be ignorant of aerodynamics and meteorology, second: gaps in their knowledge have to be filled by someone delivering his dead wrong message with great detail, patience and perseverance. Higher he be on the airline totem pole, it's easier for him to get the messages such as: "it will be blown off anyway" or "de-icing is useless but satisfies the authorities" across.
Unrealistic theory? Have a look at the last couple of pages on this thread.
How could pilots be so ignorant to perform such a hazardous act ? IMHO, first: they have to be ignorant of aerodynamics and meteorology, second: gaps in their knowledge have to be filled by someone delivering his dead wrong message with great detail, patience and perseverance. Higher he be on the airline totem pole, it's easier for him to get the messages such as: "it will be blown off anyway" or "de-icing is useless but satisfies the authorities" across.
Unrealistic theory? Have a look at the last couple of pages on this thread.
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It is easier to inadvertently take-off with ice than generally accepted. As pax in crew bus to stand-off bay I checked surroundings for ice. None on aero bridges, trolleys, various tugs and other vehicles. Couldn't see ice on other aircraft as we drove, or on the tarmac. Nobody was de-icing before departure etc etc. It was a fair bet that there would be no ice on my A321.
I looked for ice during a slow and careful external check. No visible ice. As best able I looked through each open cockpit window at what I could see of the wing leading edges. Looked carefully through the over wing emergency exits and other pax windows. Still no ice. But there was still one duck to line up, so I opened the aft galley door and had a good look at everything I could see from there. About to call it a satisfactory check and decided that while there I would also check the left horizontal stabilizer.
There was sufficient clear ice there to cause concern. In all cases, any is unacceptable. We were critically questioned about our need for de-icing by my culturally conditioned airline, but of course I insisted.
Except for my local F/O, who trusted my decision, there was not a single person who believed we just saved an aircraft and over a hundred lives by insisting on de-icing. The problem with such situations is that the de-ice equipment is not fully staffed, schedule will be disrupted, crew duty hours may be a problem with no replacements available, the cost of the de-ice, and most significantly, the loss of face when competing airlines depart without de-icing.
So while the principle of no ice, holdover times and so on are clear, there are multiple considerations that together conspire to reduce our confidence in the need for de-icing. As pilots, we are absolutely required to follow all the procedures needed to keep our aircraft airworthy.
I looked for ice during a slow and careful external check. No visible ice. As best able I looked through each open cockpit window at what I could see of the wing leading edges. Looked carefully through the over wing emergency exits and other pax windows. Still no ice. But there was still one duck to line up, so I opened the aft galley door and had a good look at everything I could see from there. About to call it a satisfactory check and decided that while there I would also check the left horizontal stabilizer.
There was sufficient clear ice there to cause concern. In all cases, any is unacceptable. We were critically questioned about our need for de-icing by my culturally conditioned airline, but of course I insisted.
Except for my local F/O, who trusted my decision, there was not a single person who believed we just saved an aircraft and over a hundred lives by insisting on de-icing. The problem with such situations is that the de-ice equipment is not fully staffed, schedule will be disrupted, crew duty hours may be a problem with no replacements available, the cost of the de-ice, and most significantly, the loss of face when competing airlines depart without de-icing.
So while the principle of no ice, holdover times and so on are clear, there are multiple considerations that together conspire to reduce our confidence in the need for de-icing. As pilots, we are absolutely required to follow all the procedures needed to keep our aircraft airworthy.
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Originally Posted by PukinDog
1. From the report: "The Federal Aviation Regulations are very specific, requiring that "no person may take off an aircraft when frost snow or ice is adhering to the wings, control surfaces, or propellers of the aircraft." The crew knew they had a contaminated wing with frozen precip adhering, yet they took-off it anyway.
If its not wet and glossy but turned opaque, and especially if there's snow present on the fluid surface, the solution has lost the ability to melt frozen precip and absorb/suspend/depress the freezing point of the water. Unless other procedures have been approved in the Ops Specs, the general rule for U.S. air carriers (121.629) if HOT has been exceeded there must be pre-takeoff contamination check accomplished within 5 mins before T/O, and it must be done from outside the aircraft.
I’ll also point to your description of some snow where you certainly imply it be allowed on an airplane’s surface…
In any case, no matter how you're trying to parse it, if it's not a dry, feathering snow readily sliding off a cold-soaked wing but is accumulating on it instead, then it must adhering somewhere...
…accumulated on de/anti-ice fluid, the fluid has failed (and) this "accumulation" of snow … doesn't meet the criteria "free of" (therefore it is considered) contaminated.
Originally Posted by PukinDog
2. The Air Florida company Ops Manual mirrored that same Reg, but with relief granted for dry snow if the Captain and person releasing the aircraft agreed conditions precluded adhering. That relief was never sought, and the mod-heavy wet snowy conditions weren't of that nature anyway. So with regards to "clean wing"/contamination", there's no question the crew didn't follow their own Ops Manual either as it existed in 1982. Ignorance of his own Manual?..or disregard for it.
And
3. Inspection after de-icing. From the Report: "Neither the Air Florida maintenance representative who should have been responsible for proper accomplishment of the deicing/anti-icing operation, nor the captain of Flight 90, who was responsible for assuring that the aircraft was free from snow or ice at dispatch, verified that the aircraft was free of snow or ice contamination before pushback. Ignorance of his own Manual? or disregard for it.
And
3. Inspection after de-icing. From the Report: "Neither the Air Florida maintenance representative who should have been responsible for proper accomplishment of the deicing/anti-icing operation, nor the captain of Flight 90, who was responsible for assuring that the aircraft was free from snow or ice at dispatch, verified that the aircraft was free of snow or ice contamination before pushback. Ignorance of his own Manual? or disregard for it.
Originally Posted by PukinDog
4. Use of reversers. The Air Florida Ops Manual at that time also included Bulletins warning of possible clear ice formation on leading edge devices while using reversers on the ground with snow present. There were also a series of Bulletins and avisories regarding rotation/pitch and roll issues with contamination on the leading edges, and recommended procedures for takeoffs into icing conditions or where contamination may be present. The Captain used the reversers for 30 to 90 seconds at the gate, after de-icing. Ignorance of his own Manual? or disregard for it.
A buildup of ice on the leading edge devices may occur during ground operations involving use of reversers in light snow conditions. Snow is melted by the deflected engine gases and may refreeze as clear_ ice upon contact with cold leading edge devices. This buildup, which is difficult to see, occurs in temperature conditions at or moderately below freezing. Crosswind conditions can cause the ice buildup to be asymmetrical, resulting in a tendency to roll at higher angles of attack during subsequent takeoffs.
In your incessant arguments that this situation was complicated by a couple of bafoons to knew little and cared less. You continue to cite what you believe was a deliberate maneuvering of their aircraft to be “deiced” by the jet blast of a preceding airplane. I hope to goodness that you are never recorded, in a moment of utter frustration, uttering a hyperbole (such as “I’d sell my oldest child for a parking place!) because someone with your penchant for not understanding the potential uses of such parts of speech in, at least the Americanized version of, the English language is going to think you more than just a bit nuts – when those of us here have come to recognize that you are certainly not nuts.
While we are looking more carefully at the contents of that company’s Ops Manual, it might interest you know that the following was contained in that manual as well – as prescribed by the airplane manufacturer (again, from the Accident Report, page 37)
Section 3A-7, page 2, of the August 20, 1973, issue of the B-737 Operations Manual, Supplementary Procedures, Ice and Rain Protection, “Wing Anti-ice,” states: There are two methods recommended for operating the anti-icing. The primary method is to use it as a deicer, by allowing the ice to accumulate before turning it on. This procedure will provide the cleanest airfoil surface, the least possible runback ice formation, and the least thrust and fuel penalty. Normally, it will not be necessary to shed ice periodically unless extended flight through icing conditions is necessary (holding). Ice less than 3 inches thick will have little effect on airplane handling, therefore, the ice accumulation may be allowed until the icing condition has been passed. The secondary method is to turn the wing anti-ice switch on when wing icing is possible and use the system as an anti-icer.
You can – and you have – criticized these crewmembers quite heavily – they and their families paid – quite heavily for any mistakes they may have made – certainly relying on what and how they were trained, relying on a competent ground crew to deice and anti-ice their plane – doing what everyone else that day appeared to be doing – wasn’t all a mistake.
Do I have an agenda? You bet. And I thought I made that perfectly clear in my first post on this thread. The reason I interjected my original comment into this thread was not to start an unwanted argument about what should have been done or what the flight crew should have known and did know. My original comment was to correct what I saw as an incorrect impression that it was a the low engine takeoff power that caused the accident. The NTSB officially, and at least one NTSB participant (quoted by one of the posters here) collectively agreed that the engine power setting did not cause that accident. The NTSB reached the conclusions they reached. Some of us in the aviation world disagree with those conclusions … welcome to the world of individuality. There will inevitably be doubts and incomplete knowledge in almost any accident scenario … and I sincerely believe THAT is the primary reason that the NTSB does not publish “Accident Causes.” They publish “Probable Causes” of accidents. Do I expect the conclusions reached in this accident to be changed? …not hardly! Does that mean I agree with all that was said in that report? …again, not hardly!
One thing I hope I am never caught doing is besmirching the reputation of fellow aviators that have experienced unfortunate turns of events. I’ll leave the allegations of “lack of awareness;” of “providing Laissez faire ‘non-answers’ to questions;” and the like to others. I would hope that any professional on this or any other forum, or in any other exchange of philosophy or ideas or questions, will examine all there is to examine – including the concerns, opinions, and beliefs of others – not to the exclusion of facts, but perhaps to bring slightly differing highlights to those facts … to better understand and appreciate what happened …and then do all they can to learn from what those actions have provided.