I have heard of "the rope trick" (either removing, or sometimes just "polishing smooth") being performed in Alaskan bush flying before.

No fair commenting on "interesting Chinese water" trick without telling what it is. :=

The rope technique is used by GA pilots in many places. Hardly a deep secret, since even I have used it.

This take-off would be illegal in Canada today, but only according to fairly recent regulations. Just a few years ago, it might have been legal.

Here is what the Regs say, in this part of the world anyway

The key word is "adhering".

That definition is the same as it was 10 years ago and is still unchanged because when an aircraft is de-iced and anti-iced and it continues to snow, by the time it begins its take-off roll, the wings may very well be covered in snow, but snow that does not adhere to the critical surfaces of the aircraft thanks to the anti-icing fluid. Before the new principles were adopted, (sept 1990 I think in Canada, following the accident report on the March 1989 Dryden accident) that same principle could be applied for dry snow: it did not "adhere".

After 1990, they had to keep the above definition but the philosophy changed, although I can't find the exact wording change in the regs they used to apply the new principles. .

When very dry snow falls on a very cold and clean aircraft (like when it's -25 Celsius on the ground) none of it sticks to the aircraft. One can blow on it and it flies off, leaving no trace on the surface of the aircraft. Back in those days, our spoilers were painted black. When we wanted to ascertain that our aircraft was "clean", one pilot would walk back in the cabin and look at the wings while the pilot remaining in the cockpit would raise the spoilers. If the spoilers were clean and free of snow while in the vertical position, we could take off, if not we would have to de-ice. They were painted black so that any snow or ice would stick out.

Russia is now where Canada was in August 1990 and everyone acts as though it was never done in these parts of the world.........

Here is a picture of such an aircraft with a black spoiler.......

https://lh3.googleusercontent.com/-K...-k/spoiler.jpg

Water check: Special book.
 

Checkboard;

My apology, just did not want to appear to know all. The procedure used as described by Captain Smith was to catch a few drops of fuel in the cupped palm of one hand and then gently blow on the fuel to cause some evaporation. If evaporation did not occurr then the liquid was water.
" China Pilot" is a very special book. It's a book written in pilots' language that only a fellow pilot can fully understand. An example is when converting onto the C119 Felix said of the stall sequence " I shoved the nose down and the power up and tucked the sounds and feeling into my memory " It's the flying life of a soldier of fortune who upon retirement back to the USA said " the world is flat after life in asia " Michael Collins of Apollo 11 said "China Pilot " is a wonderfull book. Buy it and give yourself a treat, at the moment Amazon Books have 5 copies in stock.

This is a totally incorrect and misleading statement which, in my opinion, should be removed before the less well informed start to believe it's true..!!

The glycol present in the anti-icing fluid will effectively melt the snow falling on it and the fluid will become progressively more and more diluted as time passes. Eventually the glycol will be diluted to a level where it becomes totally ineffective and the snow will start to form or accumulate on the treated surfaces. At this time the so called 'Holdover Time' will have run out and the aircraft will require a further de-icing/anti-icing treatment.

While under certain conditions any anti-icing fluid residues remaining in contact with the structure may prevent the accumulating snow from bonding or freezing to the surface of the aircraft, there is no guarantee of this and certainly no guarantee that this partially melted snow will effectively flow off on any anti-icing fluid residues that may be still present.

To quote from Section 3.15 in Edition 26 of the AEA Recommendations for De-icing/Anti-icing Aeroplanes on the Ground, "..Holdover time will have effectively run out when when frozen deposits start to form/accumulate on treated aeroplane surfaces.." At this time a further de-icing/anti-icing treatment would of course be required.

Thank you, Ice-bore! It's really surprising how little fellow pilots (?) understand when it comes to this subject. Or maybe scary is the correct word?

but to me the way to address the problem are the SOPs, being approved by a regulator, and monitored by the Operator. We can't afford to make all pilots believe, but we can try better to make them "adhere"

Are you claiming that when an aircraft takes off during snow showers and within the allowed hold-over time, thanks to the magical effect of glycol, the snow instantly turns into water and the wings just look wet, as though it was just raining? There is no presence of slush, partially melted snow, snow crystals, nothing that has consistence?

In fact there is, and that is why the Regs, here anyway, still allow take-off as long as none of that stuff adheres to the surfaces.......

Of course anyone here is free to offer their opinions ... but what I have offered is not “conjecture” any more than it is questioning the conclusions reached based on the information gathered ... as differentiated from the material eventually included in the official Accident Report. So, let’s look at facts and questions ... and let the reader come up with his/her own “conjecture.”

Fact: According to the Accident Report, the Trump De-Icing Vehicle did not incorporate the “mix-monitor” which allows the operator to ascertain that the desired mixture is indeed being delivered at the nozzle.

The Trump De-Icing Vehicle used to deice/anti-ice the accident airplane had recent “repairs” completed that resulted in the nozzle dispensing fluid at 18 percent glycol mixture from the deicing wand at a minimal flow rate, but when the operator increased the flow rate, all of the additional volume flow came from the heated water tank, and none from the glycol tank – effectively lowering the solution percentage by an unknown but substantial proportion, potentially reaching a solution of “zero glycol” being dispensed.

Question: Why is it that this information was not included in the Accident Report?

Answer: Up to you.

Question: Could the deicing/anti-icing solution provided by this “repaired” deicing vehicle, in combination with the ambient temperature of 24F, applied to a “cold-soaked” airplane, have had any effect on whether or not ice could accumulate on the aircraft? Could this solution, in combination with any potential snow fall, have had any effect on whether or not ice could accumulate on the aircraft?

Answer: Up to you.

Fact: Of course a snow-covered or an ice-covered wing would not be recovered from the Potomac. That is precisely why it is important to understand just how the deicing and anti-icing of the airplane took place – at least as important as knowing what snow actually fell between that process and the takeoff. All 3 aircraft (the accident aircraft, the aircraft preceding and the aircraft following) were in the same line for takeoff on the same runway. All 3 aircraft were exposed to the same weather conditions (including snow fall) for the same length of time.

Question: Why would only one of those aircraft (the one in the middle) have had a problem?

Answer: Up to you.


The first of the 3 causes of the accident, cited by the Accident Report:
“...the flightcrew’s failure to use engine anti -ice during ground operation and takeoff...”

Fact: The CVR transcript shows that during the “after start” checklist (which was conducted as a challenge/response exercise) at the F/O’s challenge (reading the checklist) item “Anti-ice” (referring to the engine anti-icing switches) the response, provided by the Captain, is indicated as “OFF,” and is shown within parentheses. The legend for the CVR shows that any transcript content contained within parentheses indicates “questionable text.”

Question: In that there are only two positions for those switches, either “ON” or “OFF,” when the response, as recorded on the cockpit voice recording tape, is not clear, why was “OFF” chosen to be placed within those parentheses instead of the only other alternative, “ON”? This is the only indication that engine anti-ice was not used. If the actual recording is not clear, and there are only 2 choices – why was “OFF” determined to be the response that should be included within those parentheses, instead of “ON”?

Answer: Up to you.

(Information: Just in case anyone may be interested ... when the wreckage of the airplane was retrieved, the position of the switches on the overhead panel and the position of each of the 3 associated valves in each of the engines were inconclusive – which is not uncommon for the amount of impact destruction experienced.)


The second of the 3 causes of the accident, cited by the Accident Report:
“...their decision to take off with snow/ice on the airfoil surfaces of the aircraft...”

Fact: for that day, the recorded information regarding snow fall was as follows...
Moderate snow began at 1240 and ended at 1320.
Heavy snow began at 1320 and ended at 1525.
Moderate snow began at 1525 and ended at 1540.
Light snow began at 1540 and ended at 1553.
Moderate snow began at 1553 and ended at 1616.

Again, the airplane preceding and the airplane following the accident B-737 were subjected to the same processes and weather prior to takeoff.

Question: If it was the snow fall that accumulated on the B-737 between the gate and their takeoff that caused the accident – what prevented the other two airplanes from suffering the same fate?

Answer: Up to you.


The third of the 3 causes of the accident, cited by the Accident Report:
“...the captain’s failure to reject the takeoff during the early stage when his attention was called to anomalous engine instrument readings.”

Fact: The first time the F/O expressed anything that sounded like he was questioning something was at 1600:02 when he said, “That don’t seem right does it?” This was followed at 1600:05 by “Ah, that’s not right” and then an inaudible comment, followed by the Captain saying “Yes it is, there’s eighty” at 1600:09. Then at 1600:10 the F/O said “Naw, I don’t think that’s right, followed at 1600:19 with “Ah, maybe it is.” Two seconds later, at 1600:21, the Captain says “Hundred and twenty.” Then the F/O says “I don’t know.”

Observation: The committee that listened to the actual CVR recording apparently concluded that the F/O was expressing a concern over an “engine anomaly,” and of course, that is certainly a possibility. For almost 20 seconds it would appear that both the Captain and the F/O were attempting to recognize something in the cockpit that was causing the F/O to make the comments he made – apparently without being able to identify what that was.

Question: What would have been anomalous to the F/O and not to the Captain? Would this be the only thing that would have caused the F/O to make the comments he made?

Answer: Up to you.

Fact: A landing airplane was on final when the accident B-737 was cleared into position and cleared for takeoff. Approximately 20 seconds elapsed from the time the tower advised that there was a landing airplane on final at 2 and ½ miles behind the departing B-737 (at 1559:28) to the time the CVR recorded the sound of the engines spooling up toward the desired takeoff setting (at 1559:48). Another 14 seconds had passed when the F/O first indicated that there was something that he thought didn’t “seem right” (at 1600:02). Another 7 seconds had passed when the Captain noted that the B-737 had reached 80 knots (at 1600:09).

Question: How far behind the B-737 was the landing aircraft at these points?

Answer: Up to you.

Fact: At 1600:11 the landing aircraft called, “Fourteen fifty-one, cleared to land over the lights” (which extended 2400 from the runway’s threshold). We do not know the specific point over those approach lights the landing B-727 actually was at the time of that radio call.

Question: At this point, how far behind the B-737 was the landing aircraft?

Answer: Up to you.

Question: Would you have aborted the takeoff?

Answer: Up to you.


Fact: The accident report states “there were other incidents similar to this one reported, in which the crew was able to overcome the contamination, but they needed the proper thrust level of 2.04 EPR.” On the same day as the Air Florida accident, another B-737 attempted a takeoff out of Oslo, Norway, where the taxi and takeoff were conducted during a snowstorm. During the takeoff, as the crew began to rotate, the airplane pitched-up and due to the asymmetry of the deformity of the wings, began a roll. Neither the pitch nor the roll was controllable by the crew. Even though the throttles were “slammed” to the firewall immediately and the fact that the pilot used full opposite aileron and full opposite rudder, the pitch and roll of the aircraft was not controllable. Apparently, due to the radical bank angle reached (approaching 90 degrees), the nose dropped back down toward the horizon, and with the throttles fully forward, the airplane began to accelerate. As the acceleration continued, apparently lift was produced over the outboard portions of the wing, including the ailerons, and the crew was able to roll back to level flight. The crew recovered the airplane; but that recovery was below 100 feet above the ground.

Question: Why were the only incidents of B-737 pitch-up and/or roll-off described in the Accident Report those that were recoverable?

Answer: Up to you.


My first inclination is to say “from your lips to the hearts and minds of aviators everywhere.” However, I am mindful of the fact that most of those aviators are heavily influenced by all sorts of external factors – their boss, their job, their salary, etc. Most of these external factors have a tendency to influence the way individuals interpret specific issues to result in the most advantageous and to the least negative impact possible. To that end, I’m taken back to the simple fact that the FAA has maintained that the only time they feel it necessary to specifically define a word that they use in their regulatory documents is when the definition they desire to use is either not included in the dictionary or the dictionary definition is not the meaning the FAA wished to convey. Terms that are used in the regulations are either defined in the regulations (some place) or they rely on the traditional understanding (i.e., dictionary definition) of the term. Since the term “adhering” is not found in the regulations – in those parts or sections were there are requirements laid out for taking off or landing in inclement weather conditions or in their primary rule dealing with definitions, the only definition that can be applied to this term is the definition found in the dictionary. According to Merriam-Webster, the term “adhere” means (in the context used in these rule sections) “...to hold fast, or to stick through gluing, suction, grasping, or fusing.”

As long as the rule uses that term, I think we all have to recognize that there is likely to be a substantial number of people who will find that definition to be a way to continue operations when that continuation may not be the most conservative decision.

"I am mindful of the fact that most of those aviators are heavily influenced by all sorts of external factors – their boss, their job, their salary, etc."


reading through the thread, I worry that I might be in the minority. When I fly, I have two primary considerations: my safety, and that of the passengers behind me.

If those considerations don't suit my boss, then I will soon be bossless. However, in my minimal experience, my bosses have been on the same channel. Even if only because a mighty screw up is going to cost them big time.

As before. Contamination on any surface = no fly. End of.

If any boss doesn't like that, then that's tough. Stuck up the pointy end, it's my responsibility and I take that seriously, not least because my a**e is equally on the line.

...and if I ran my own airline, you would be the kind of person I would hire! I believe in the tried-n-true adage ...”you think training is expensive, try an accident!” Unfortunately not all airline owners, managers, etc. believe as you do ... and even more unfortunately, there are far too many young and eager, still “damp” behind the ears, fledgling pilots that will take what they can get because they believe that’s all they will be offered. I’m with you, my friend, I’d rather sell cars, mow lawns, bag groceries, whatever ... and still be here to take care of my family. Death is a rather permanent state that I’d like to avoid for as long as possible.

Canada icing conditions
 

Not wanting to hijack the thread (mods please move it if you like)
Monday 16th flew from an Alberta location to one in Texas - Flew commercial as the company units were busy. Pushed back at 10 mins late 07:10. The aircraft had been at gate for over 8 hours over night and the temps were all below freezing, but no precip in the preceeding 12 hours.
Promptly taxied past all the WestJet aircraft being de-iced and lined up and rolled - needless to say studied stbd wing very closely to see any signs of ice, but it did appear clean.
If the locals de-ice all their overnighting aircraft, why not the legacy US carrier?

Yes, where the aircraft has been anti-iced with a Type II or IV fluid. I'm not a chemist but I believe this takes place due to chemical action rather than magic.

Due to the thickening agent present in Type II and IV de-icing/anti-icing fluids these fluids are able to remain on and protect aircraft surfaces for a period of time (see holdover time tables for applicable times).

As the snow flakes impinge on the fluid film they melt, due to the low FP of the glycol in the fluid, progressively diluting the fluid and yes the surface does look wet at this stage. Depending on the intensity of the snowfall it may take a few seconds for the individual snow flakes to melt but once slush or snow is seen to be building up on the fluid film the holdover time will have expired and a further treatment will be required.

The viscosity of the fluid is relatively high when applied to the surfaces of an aircraft on the ground, however, as the aircraft accelerates during take-off the shearing effect of the airflow over the wings breaks down the structure of the fluid, reducing the viscosity and allowing it to flow off to provide a clean wing. Clearly if the fluid film has snow on top of it, it will be prevented from working as designed.



It would be appreciated if you could let us know where, in your regulations, it allows you to take-off with snow/slush present on top of an applied film of anti-icing fluid...

Ice-bore is correct.
Extract from a Ground Icing Ops Manual :

In a non-regulatory document called
TP 10643 - When in Doubt... - Transport Canada

in paragraph 77

My company MANOPS also says:

But the law in Canada is the Canadian Aviation Regulations, part 602.11

Part VI - General Operating and Flight Rules - Transport Canada

Notice that the word "adhere" is always there, when the law could have been written with the exact same wording but with the word "present" instead of "adhere". Why ?

"present"

Like blowing snow across a cold flat surface that does not accumulate on such surface

"adhere"

Where it does accumulate

If you start your taxi (after dispatch) and the snow has already accumulated on the wing even in patches, it has "adhered" and you should be in violation of a hard rule if you dispatched that way.

A clean wing/engine etc, at dispatch, that subsequently accumulates snow or ice falls under a different operational SOP (one that minimizes the effect)

A wing/engine that accumulates ice in the air falls under a design regulation as well as an operational SOP

to adhere...
 

to adhere (source)
verb (used without object)
1. to stay attached; stick fast; cleave; cling (usually followed by to ): The mud adhered to his shoes.

The problem is the use of language … and I don’t necessarily limit that to the use of the English language. All languages present its users with some difficulty in expressing exactly what is meant. That’s why language is described as consisting of 3 parts: what is said, what is heard, and what is meant. Of course when snow is “blowing” across a surface it doesn’t “accumulate” on that surface. But I think anyone would be hard-pressed to say that simply because snow has “accumulated” on a surface, that it has also “adhered” to that surface.

There are a lot of the Canadian rules that are quite direct and to the point and would probably be preferred by most aviators – given the chance … but even then, the language our friends in Canada use can present the same sort of understanding or interpretation questions. For example the Canadian rule quoted as saying “…conditions are such that frost, ice or snow may reasonably be expected to adhere to the aircraft…” Then the question becomes, what is “reasonable?” Does “expected” mean that it is suspicioned to have adhered already, or will, within a short time in the future, begin to adhere? If it is expected in the future, what time frame would be acceptable – or – how short is short? Or, do we throw it all in the air and let the lawyers figure it out?

Using the word “accumulate” doesn’t necessarily solve these issues either. If any rule was changed to say takeoff must not be attempted when ice or snow has accumulated on the wing … then virtually any snow fall would prevent virtually any taxi time between “deicing” and “takeoff”. Anyone who has taxied from a gate to a runway for takeoff when snow was falling, can easily attest to the fact that “some” snow accumulated on the wings prior to taking off. If the parameters of such an accumulation cannot be clearly articulated and then adequately communicated, then, the conversation between the two Air Florida pilots becomes a lot more prophetic …

Captain: Right there is where the icing truck…they oughta have two of them, you pull right…
F/O: …right out
Captain: Like cattle … like cows right.
Captain: Right in between these things and then…
F.O: …get your position back
Captain: Now you're cleared for takeoff
F/O: Yeah and you taxi through … kinda like a car wash or something
Captain: Yeah

I know there are some airports who use precisely this method … and I would presume that there have been very few, if any, takeoff incidents attributed to ice or snow presence, accumulation, or adherence at those airports. The problem with this method is one of expense … both initial and maintenance … and then there is always going to be the environmentalists that would need to be satisfied with respect where the runoff would be captured and disposed of properly.

:hmm: Ahhh … the simple life of an aviator …

I note a few references to the crash of Air Ontario Flight 1363, a Fokker F28 which crashed into a forest less than a kilometer from the end of the runway at Dryden Ontario in 1989. The accident resulted in 24 fatalities, including both of the flight deck crew and the senior flight attendant. There were 45 survivors, including a second flight attendant.

Subsequent to the accident and the official accident report the government formed a Commission of Inquiry chaired by the Honourable Vincent Mashansky to examine not just the immediate cause of the accident (which was unquestionably the decision of the pilot to depart the runway with snow-contaminated wings) but also all of the causal factors which may have influenced the captain’s unfortunate decision to attempt the takeoff, given that he had a reputation for being cautious and responsible (although this may have contributed to his decision, inasmuch as he no doubt also felt a responsibility to get his passengers to their destination, particularly as it was the start of a school break and many passengers were to connect to flights which would take them to vacation destinations).

Justice Mashansky’s 1,300 page report is very comprehensive. It could serve as a textbook example of how all of the holes can line up, insofar as the Commission found that virtually everyone having anything to do with Flight 1363 and this aircraft made errors or omissions which individually might be deemed insignificant but collectively led to a smoking hole in the ground. (To be clear, the interpretation that the errors might be deemed insignificant is mine alone… Mashansky was less forgiving). These factors included the ground worker who fueled the craft but failed to bring the snow on the wing to the captain’s attention, and the senior flight attendant who dismissed the concerns expressed by a nervous passenger, as well as the junior attendant who deferred to the judgement and authority of her senior colleague.

Perhaps most relevant to this discussion the Commission examined the responses of two surviving passengers… an off-duty Air Ontario Dash 8 captain and an off-duty Air Canada DC9 captain. One of these testified that he knew that the aircraft would not fly (emphasis mine) but presumed that the captain knew this too. In any case, he testified that he presumed that the captain planned to monitor the snow on the wings during the takeoff roll and would abort the takeoff once he saw that the snow was adhering to the wing. According to the testimony of others this method of determining wing contamination during the takeoff roll was not entirely uncommon at Air Ontario (which had evolved from Austin Airways, flying DC3 and Otters around northern Canada) and if I recall correctly Justice Mashansky (a pilot himself) found this practice to be unsatisfactory to say the least. We can be certain that the regulations drafted subsequent to this accident were not intended to allow pilots to make their determination of whether snow and ice were “adhering” when they were halfway down the runway approaching V1.

It’s nice to see that many on this board say that they would have… had they been passengers… prevented the takeoff attempt. However, in this context it ought to be noted that the other off-duty captain was also aware of the condition of the wing, but felt that professional courtesy and respect required that he remain silent. The two passenger-pilots had something like 18,000 hours experience between them while the two at the pointy end had something like 130 hours of combined experience (on type).

I recognize that this report is now twenty years old and we now have a greater appreciation of human dynamics (if only because of subsequent incidents and accidents). Taken as a whole the report was (and remains) a damning indictment of the airline`s owners and managers (largely one and the same) and Air Canada (Air Ontario`s code-share partner and part-owner at the time). Ultimately, of course, the report infers that industry deregulation in the absence of adequate regulatory authority created an environment which contributed to the accident. Mashansky made 191 recommendations, and while I believe that some were acted upon I’ve a hunch that most were not. Indeed, something like 18 months after the release of the report another F28 (USAir 405) crashed at LaGuardia under similar circumstances.

I presume, of course, that I am preaching to the choir here. In fact, I hope that I am.

And I apologize to those who I've offended, given that... well, my username says much. Indeed, I was going to keep my thoughts to myself until I realized that I am one of those people who would keep my thoughts to myself even if there was a foot of snow on a wing.

Apologies for being so long-winded, and mods feel free to edit.

The full text of the report can be found here:

Commissions of Inquiry

Also, there is an episode of “Air Crash Investigation” devoted to the accident and Mashanky’s report here:

I wrote:
Let me add that after that accident some woolen threads were installed at the roots of the wings of the MD80, free to shake into the wind, in order to facilitate the identification of subtle icing Vetrone by the crew, often unnoticed.

I am grateful for correcting me.
As a matter of fact I remember that we were expected to perform a visual inspection of the tuft on the upper surface of the wings from the cabin, in case of doubt we had to open the wing emergency exit, go out and touch the surface to ensure that there was no ice.

As we all know there’s a phenomenon called cold-soaked fuel, which happens if the aircraft is parked with wing tanks not completely filled with fuel, which then evaporates. This gas expansion reduces the temperature, and so even if the outside air temperature does not fall below zero, the moisture in the air condenses and then freezes in contact with the sheet of the wing. During the walk around a 3 mm layer of frost was acceptable below the wing corresponding with the tanks.
It seems that those ice formations, resulting from the cold soaked fuel, broke during take off, causing both engine flame out which determined the crash of the MD-81 SAS in Gottrora on December 27, 1991.

So why, before their production was discontinued, a plan has been made to install de-icing panels at the root of the wings of MD 90/Boeing MD 717?

AirRabbit:
It's really moving the ardor with which you defend the actions of the crew of Air Florida Flight 90 which crashed into the Potomac January 13, 1982.
Many wise philosophers in ancient Greece argued that we should defend a friend by all means also we know he's guilty.
Nevertheless you will agree with me that the following illegalities were committed:
- They did not insert Engine Anti-ice after start, and did perform the periodic engine run up.
- They tried invain to push back (the tug connected) through the use of reverse (thus raising clouds of snow and slush).
- They knew they had snow on the wings, so that they approached the preceding DC9, in the vain hope that their jet engines would swept it away.
- They started the take off run 50 minutes after the de-icing.
- They accepted a very little separation with the landing traffic despite the poor visibility and the snow storm. (If they had to abort the takeoff? If the others were to go around?)
- They underestimated the irregularity of the engines parameters for takeoff
- They had found that the acceleration was so poor that they had reached 120 knots after 45 seconds.
- They began to rotate as per “the soft field” (I began to hear such an expression only since I'm instructing in general aviation) and then starting the rotation well before Vr.
I'm sorry but I have to tell you that History has been written.
So much time and money has been spent to establish the causes of the disaster, so justice was done and the incident would had never happened again (sic!).
So unless you have any new evidence to reopen the trial, agree with NTSB.
Let’s shout together:
“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!”

Here you are Lomapaseo.
Is this the way you like it?

Doves

If you intend to use quotes, then please use the quote function

If you have questions by all means use a question mark

If you have already concluded something, then don't atempt to intermix your opinion being supported by somebody elses quote.

I really can't sort out which is which in your post above

I will be more than happy to “agree” with you when you post something that is accurate. I’ve often said that I’m not writing to defend the flight crew. They certainly made errors. However, the errors they made did not cause the accident. I’ve been quite clear about what, in my sometimes not-so-humble-opinion, it was that actually caused this particular accident … it was the exact same thing that almost caused the B-737 to crash in Oslo, Norway on that same day, January 13, 1982.

The only place that indicates the flight crew did not use engine anti-ice is the CVR and transcript thereof … as I’ve pointed out earlier … that transcript clearly shows the response to the challenge-response checklist item “Anti-ice?” was recorded and published as “(OFF)” … and you will note the presence of parentheses around the word. If you had bothered to check what those parentheses meant, you would have found that they mean “questionable text.” In other words the committee that was listening to the actual CVR were not able to determine what was said to that particular checklist challenge item. The fact is that choosing to have the transcript show that response as “(ON)” should have been just as valid as having the transcript read the way it does. In that there are only two positions in which those switches could have been placed, those being either OFF or ON, when you cannot determine what was said – and the transcript is presented the way it is presented to show the reader that the response is UNKNOWN – how do YOU know that what was chosen to be placed on the transcript was, in fact, the actual position of those switches?
No. The crew did not attempt to use reverse thrust to push back. The practice was apparently to start the engines at the gate, and then push back. This was attempted, but the tug being used was unable to acquire sufficient traction to push back the airplane, particularly “up” the slight incline that existed at that gate (see the accident report). Recall, the airplane had just been “deiced” and as a result the ramp around the airplane – which also had been subjected to prolonged sub-freezing temperatures – and because the Trump deicing vehicle was improperly repaired and was not functioning properly, a fairly extensive amount of water was sprayed all over it, very likely resulting in a much greater than anticipated accumulation of ice – making the traction available to the tug to be much less than normal. Additionally, as I’m sure you are likely knowledgeable of such things, engines at idle thrust still produce a forward thrust component – and the ground crew, the tug driver, and the flight crew attempted to neutralize this forward thrust component by opening the thrust reversers while keeping the throttles in the idle position. Again, the tug attempted to push back … and, again, was unsuccessful. The decision was made to shut down the aircraft engines and obtain a larger, heavier tug, one equipped with tire chains to attempt the push-back. This was accomplished. After the push-back was completed, the crew again started the engines. Here’s the quote from the Accident Report:
“Witnesses estimated that both engines were operated in reverse thrust for a period of 30 to 90 seconds. During this time, several Air Florida and American Airlines personnel observed snow and/or slush being blown toward the front of the aircraft. One witness stated that he saw water swirling at the base of the left (No. 1) engine inlet. Several Air Florida personnel stated that they saw an area of snow on the ground melted around the left engine for a radius ranging, from 6 to 15 feet. No one observed a similar melted area under the right (No. 2) engine.
Note that there is no indication of “raising clouds of snow and slush” as you’ve indicated.
Undoubtedly, you are referring to a single comment made between the pilots during their lengthy taxi process, and you have determined that the description of what was happening was as a result of a determined effort of the pilots. There were a total of 2 comments to which you may be referring:
1. (1546:21)
“Tell you what, my windshield will be deiced' don't know about my wing”

2. (1551:54)
“Don't do that Apple, I need to get the other wing done ((sound of laughter)).”

In the first example, if you are at all familiar with the taxi process from the ramp to what was then Runway 36 (now Runway 1) you know it involves crossing runway 3 (now runway 4). In that the accident airplane was following behind a New York Air DC-9, when that DC-9 added power to cross that runway, given where the DC-9 engines are mounted and the fact that even more engine thrust would be needed to climb the slight incline to cross the runway than would be needed to begin taxiing again, it is likely that the thrust encountered by the accident airplane was noticeably more, and that thrust was commented on by the Captain who could just as easily – and very likely – meant it as a satirical comment – just as you might say – “just my lucky day” when you find out from your operations that the airplane you’re changing to when at JFK is on the other side of the airport!

In the second example, and again, as you may already know, the waiting area between runway 3 and runway 36 is a larger area where airplanes can wait without blocking access to the entrance to runway 36, and most airplanes park in that space angled away from blowing exhaust directly on the airplane behind them in line. However, when an airplane begins to move – either to move up to the next space in that waiting area or to taxi onto the runway, additional thrust is used, and through the turn, blows all that additional exhaust directly on the airplane waiting in that area. Additionally, as the end of that comment there are the words “sound of laughter,” indicating that the flight crew was commenting in a jocular (or frivolous) manner – indicating to many readers that the flight crew was not very serious about their jobs – I’ll call your attention, once again, to the fact that even the committee who listened intently, very likely for hours, still could not determine exactly what was recorded on the CVR, and that is why those words are contained in those parentheses.
…just as did Apple 58, taking off immediately prior to the accident airplane, AND as did Six Eight Gulf, taking off immediately after the accident airplane.
They did, indeed, accept the clearance onto the runway to hold (1558:58) … they also accepted the takeoff clearance (1559:24) – even acknowledged it (1559:26) – almost a full 30 seconds after they were cleared onto the runway to hold … but they were not advised of the position of the landing traffic until the next radio call from the tower (1559:28) advising them that landing traffic was “two and a half out for the runway.” Of course, as, again, you would also know, when the visibility is as low as it was that day – putting the responsibility on the flight crew for visually checking final for landing aircraft is a bit much … as the only folks who know about that sort of information are the guys in the tower … who apparently didn’t think that this day presented anything different from the way they regularly moved traffic at that airport.
How do you know if there was an irregularity, or if there was one, how do you know that they actually saw what it might have been? The investigators presume that the questions the F/O had raised were because of an engine anomaly – but for a full 20 seconds after the F/O’s first question, neither he or the Captain could find anything that they thought might be “anomalous” with the engines – at least neither of them said anything or did anything that indicated they recognized anything out of the ordinary.
Really? 45 seconds after what? As for the acceleration rate ... it may have been the fact that they both were attempting to find what it was that caused the F/O to ask the first question that they didn’t notice the acceleration rate – or it may have been that they had very little outside cues (due to the very limited visibility) with which to make a speed change observation and it was that fact that prevented them from assessing anything about the acceleration.
To show that this statement is in error, all you have to do is read the CVR transcript. The V-speeds were briefed to be V1 = 138 knots, VR = 140 knots, and V2 = 144 knots. The CVR transcript also shows that the Captain calls out “Vee One” (1600:31) and then 2 seconds later calls out “Easy.” There are many professional aviators who sincerely believe that the comment “Easy” was in response to what appeared to be a very quick rotation (likely occuring when the F/O began his rotation, precisely at VR speed) – and then subsequently learning about the B-737’s tendencies to rotate rather quickly and with some force when the wings were contaminated with a very small amount of contaminants. Then some 5 seconds after that (1600:37) the Captain calls out “Vee Two.”
Well, at least someone’s version of history was written, that is for sure. But I think that the conclusions reached were at least as much for expediency as anything else. I am certainly not going to generate accusations that might get me or this forum into trouble … because what we are discussing was, indeed, 30 years ago. Also, there has been a lot of education that has taken place as a result of all the discussions centered around this particular accident – which, as anyone should recognize, is a good thing. But, and as I’ve said several times now on this thread, my intent here is not intended to impugn the fine reputation or the integrity of the NTSB or of the dedicated and professional employees at the Safety Board. If someone else desires to determine who or what may have been either hurt or benefited from another “version of history” being written – let them have at it. My only motive has been a continuing effort to describe the actions of the flight crew from a slightly different perspective while providing what I believe to be clarifying information regarding the cause of the accident and, to the best I am able, set the record straight– as much as one can this long after the fact.

I will reply later point by point.
But, what about:
Which is at the root of this thread.

Most US operators require a close visual inspection and/or tactile check be performed if any contamination is observed on the wing surface (whether it's snow or ice).

FAA 8900.1 Volume 3, Chapter 27, Section 2 pertains to the process by which ground de-icing programs are approved for air carriers under parts 121, 125, and 135.

For scheduled air carriers, by regulatory requirement of FAR 121.629, a manner by which the operator can determine whether or not contamination is "adhering" to the wing must be described in detail. All flight crew members and de-icing technicians and vendors must be trained on the recognition and removal of ice and other contamination on the critical aircraft surfaces. If an air carrier lacks these procedures they cannot operate in ground icing conditions.

The common practice is a close visual inspection of areas suspected of having contamination and often a tactile inspection to determine whether or not de-icing is required and after the de-icing process to determine that the contamination has been adequately removed. In short, in the US all snow must be removed from the wing either by mechanical means (guys with brooms), by putting the aircraft in s heated hangar and letting the snow melt off, or if the temperature is such that ice will not accrue - using heated water to remove the snow. Of course using the glycol/water mixture is also an option though airlines try to avoid it due to the cost.

I guess there is not much scope to experience deicing methods in Hawaii but your hot water choice conjours images of the FO climbing out of the overwing exit with a jug of boiling water from the galley.:E

Island-Flyer Welcome on board. I envy you for the place where you are living. I remember that all American pilots who flew with me for an airline in the Gulf, in the late 90's, often said that they would be retiring in Honolulu. It never snows there does it!? Thank you for copying / pasting the FAA rules (I’m supposed to know them because I have an ATP), about aircraft de-icing. How do you see if there is a deposition of snow, ice, or bird feces on the upper surface of the horizontal stabilizer of a DHC-8? Does it apply also to people like me who has 22,000 hours? Of course I always left other fly desks, because I've always preferred, and still prefer, the "stick and rudder". Is it too little 35 years and over of flying in Europe, of wich at least ... let’s say ... many thousand hours in conditions of snow, ice, etc.. etc.. etc..? Have you ever seen this video?: Tailplane Icing Look and learn from other’s experience. Let’s shout together: “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!!!" Fly Safe DOVE

Of course it would be somewhat foolish to completely dismiss your recommendation – 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?

to AirRabbit
 

what do you actually mean:

" Is that acceptable to the myriad of operations that take place daily in locations where snow appears during winter operations?"

are you trying to suggest, that because it snows so often and so many airplanes operate in winter conditions, a clean wing concept is not acceptable? It might even cost money and maybe cause delays?

By all respect to your ex mil, ex airline, now evaluation what ever that means -background and even claiming to have an ATPL, you should know better.

There is no option for clean wing! How farking difficult is that to understand? Why do all evaluators, midwifes, clerks, PPLs, wanna be pros etc try to prove it different?

A lot of lives have been lost because persons thought a clean wing concept is not necessary. A lot of lifes will be lost in future, because still some idiots dont learn from mistakes and try to know it better.

make it clean and keep it clean

"make it clean and keep it clean"

Nothing more needs to be said. delay? Extra cost? So damned what.

The flight before got airborne, as did the one after eh? Simple maths therefore suggests a one in three chance of not making it.

Not particularly good odds are they?

Really, there is enough experience and worse, enough buried dead, to make the point perfectly clear. The regulations stipulate it. The SOPs stipulate it. Common sense stipulates it.

Even the 'Bus computers can't change the basic physics of flight.

Contamination = no go.

Mr. warmkiter and Mr. rabski:

Thanks for the simplistic response (and that is NOT an insult) – with which, by the way, I completely agree! As I said earlier, from your lips to the hearts and minds of aviators everywhere! It certainly isn’t me that you have to convince ... it’s the airline owners/operators and the various regulators who have to deal with those owners/operators.

AirRabbit At 1538:16 while accomplishing after-start checklist items, the captain responed “off” to the first officer’s callout of checklist item ‘anti-ice.”… …During preparation of the CVR transcript, members of the CVR group could not agree on the response to the checklist callout “anti-ice”. The majority believed that the response was “off,” but that word was put in parentheses in the transcript to indicate questionable text. The Federal Bureau of Investigation (FBI) Audio Laboratory was requested to perform an independent examination of that portion of the tape. The FBI concluded that the response to the checklist callout “anti-ice” was “off.” … … Each of the two engines was equipped with a thermal anti-ice system, composed of three anti-ice valves which are designed to open when the respective engine anti-ice switch is placed ON. The inlet guide vanes and nose cones use 8th stage compressor bleed air and the cowl anti-ice system uses 13th stage air. The left engine’s 8th and 13th stage engine bleed air ducting on the right side of the engine was crushed between the 1:30- and 4:00- o’clock positions. The engine’s nose cowl thermal anti-ice valve was closed. The main bleed air valve was closed, The fuel heat valve was closed. The left inlet guide vane anti-ice valve was closed. The right inlet guide vane anti-ice valve was open and free to rotate. The air turbine starter was not visibly damaged. The right engine’s right inlet guide vane anti-ice valve was closed. The left inlet guide vane anti-ice valve was not recovered. The nose cowl anti-ice valve was closed. The engine bleed valve was closed. The modulation/shutoff valve was closed.The fuel heat valve was closed. The air turbine starter exhibited no visible damage. The pressurization and bleed control was not visibly damaged. The control was disassembled and no mechanical discrepancies were noted, except that it was clogged with water and dirt. The 8th stage and two 13th stage antisurge bleed valves functioned normally. Adcording to the tug operator, the aircraft’s engines were started and both reversers were deployed. He then advised the flightcrew to use only “idle power.” Witnesses estimated that both engines were operated in reverse thrust for a period of 30 to 90 seconds. During this time, several Air Florida and American Airlines personnel observed snow and/or slush being blown toward the front of the aircraft. When the use of reverse thrust proved unsuccessful in moving the aircraft / back, the engines were shut down with the reversers deployed. …At 1540:42, the first officer continued to say,. “it’s .been a while since we’ve been deiced.” At 1546:21, the captain said: “Tell you what, my windshield will be deiced, don’t know about my wings.” The first officer then commented, “well--all we need is the inside of the wings anyway, the wingtips are gonna speed up on eighty anyway, they’ll shuck all that other stuff.” … At 1548:59, the first officer asked, “See this difference in that left engine and right one. The captain replied, “Yeah.” The first officer then commented, “I don’t know why that’s different - less it’s hot air going into that right one, that must be it -- from his exhaust - it was doing that at the chocks 5/ awhile ago. . . .ah.” At 1551:54, the captain said, “Don’t do that - Apple, I need to get the other wing done.” …The deicing/anti-icing of Flight 90 was completed at 1510. … …At 1559:46, the sound of engine spool up was recorded, …. …Between 1600:05 and 1600:10, the first officer stated, “. . . that’s not right. . .,” to which the captain responded, “Yes it is, there’s eighty.” The first officer reiterated, “Naw, I don’t think that’s right.” About 9 seconds later the first officer, added, “. . . maybe it is,” but then 2 seconds later, after the captain called, “hundred and twenty,” the first officer said, “I don’t know.” From 1559:46 to 1600:21 ...and 1558:37, the first officer asked, “Slush (sic) runway, do you want me to do anything special for this or just go for it.” (The first officer was the pilot flying the aircraft.) The captain responded “unless you got anything special you’d like to do.” The first officer replied: “Unless just take off the nosewheel early like a soft field takeoff or something; I’ll take the nosewheel off and then we’ll let it fly off.”
Let’s shout together: “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!” Fly Safe DOVE

I’m not sure how many more times I’ll have to say this to get the point across ... the accident airplane DID NOT crash because of the accumulation of snow fall experienced between the gate and the takeoff. The aircraft crashed because it was deiced with hot water – that process specifically deposited water on the entire aircraft – fuselage, wings, engine inlets, everything. Where upon that water promptly froze – deforming the wings, and producing the effect that the B-737 had been known for doing – producing the same effect that almost crashed the B-737 departing from Oslo, Norway on that same day – producing an unexpected and uncontrollable pitch-up – to a point that was not recoverable – regardless of what control application was applied by the flight crew. This was not a “one-in-three” chance of snow fall exposure resulting in an accident - the reason that the airplane preceding the accident airplane and the airplane following the accident airplane did NOT crash is that they were merely exposed to the same snow fall experienced by the accident airplane – NEITHER of them were deiced with WATER – as WAS the accident airplane.

to AirRabbit
 

thats good news. one aviator less to be concerned about. :-)

I have to say that i havent met too many operators/airlines you have to convince, that the clean wing concept is the only way to do it. Its quite the opposite. In the SOPs its clearly written, that the aircraft must be operated with a clean wing only. No manufacturer or legislator would accept any deviation from this.

Its us, the pilots who deviate from the SOPs and finally cause the accidents. We as pilots have to take care that every one of us understands the importance of the clean wing concept.

Here comes the tricky part. As soon as some pilot starts to fool around and takes a chance not to de-ice or communicates to other pilots why it is not necessary to de-ice, the seed for the next accident is laid.

The foolish comments like:"dry snow will be blown away" or "the snow is not "adhering" to the surface", are perfect examples of how the cancer of misinformation is passed on. That particular flight may get away with it, but somebody will take an example of it and he might not be as lucky.

Thats why we, as the last line of defence, have to show zero tolerance to any deviation of the SOPs. If not us, then who?

This by the way. this applies pretty much to all other SOPs too. Its the collective behaviour of a group of pilots within a company, which makes the safety culture. Deviation may work well once for a pilot with superior skills or just plain stupid luck, but for a group of pilots it will be deteriorating the level of safety.

Flying is expensive, delays and de-icing cost money. Try an accident, that is even more expensive.

AirRabbit wrote:

wouldn't the preceding and following aircraft have gone through the same de-icing station?

"I’m not sure how many more times I’ll have to say this to get the point across ... the accident airplane DID NOT crash because of the accumulation of snow fall experienced between the gate and the takeoff. The aircraft crashed because it was deiced with hot water – that process specifically deposited water on the entire aircraft – fuselage, wings, engine inlets, everything. Where upon that water promptly froze – deforming the wings, and producing the effect that the B-737 had been known for doing – producing the same effect that almost crashed the B-737 departing from Oslo, Norway on that same day – producing an unexpected and uncontrollable pitch-up – to a point that was not recoverable – regardless of what control application was applied by the flight crew. This was not a “one-in-three” chance of snow fall exposure resulting in an accident - the reason that the airplane preceding the accident airplane and the airplane following the accident airplane did NOT crash is that they were merely exposed to the same snow fall experienced by the accident airplane – NEITHER of them were deiced with WATER – as WAS the accident airplane."


You can say it as many times as you like, but you will still be missing the basic point.

It doesn't matter whether you have ben de-iced with standard fluids, hot water or Bishop's Finger mixed with Baileys, as a flyer, it's YOUR responsibility to ensure surfaces are clean before aiming at the blue bit. How bloody complicated is this FFS?

Left seat? YOUR RESPONSIBILITY.

YOUR RESPONSIBILITY TO MAKE SURE IT'S ALL CLEAN.

So, it wasn't proerly de-iced and it froze again. IME, nothing new there.

FFS, it's really not that difficult is it?

OK, somebody didn't de-ice properly. The de-icing mixture wasn't correct. The Lear Jet in front of me didn't blow the snow off the way I expected, etc. etc.

Christ, despite my comments in another thread, I hope to hell I never get anyone with your attitudes in the RH seat when I'm flying.

I want to live to retirement thank you. If that means spending some of my employers' hard earned on excessive de-icing, then I couldn't care in the slightest.

Beats the hell of of the alternative...

Mr. Doves:

I’m not going to go through the process of quoting your recent post ... so please forgive the fact that you may have to re-read your post to determine the specific points to which I’m addressing my comments ... but, I suspect you’ll probably be able to figure it out.... as I think you kindly provided “red” type for the relevant comments...

It shouldn’t take a rocket scientist to determine that an electrically controlled valve (taking both electrical power and pressure to open it) closes when both electrical power and engine pressure are removed - and there are very few (if any) who believe that the engines remained running providing both electrical power and engine pressure after the crash. Without power and pressure – what position would the valve resume? Right ... it would CLOSE. And, in case that isn’t clear enough, here’s a quote from the Accident Report...
However - it wasn't the use or the non-use of engine anti-ice that caused the crash. Yes, there was ice blocking the PT2 probes ... and that caused the EPR readings to be higher than actual. But there was still 75% power being produced by both engines. That was sufficient to get the airplane to at least 150 knots - but the airplane crashed anyway. So power setting - with or without engine anti-ice - was not the cause of the accident.
I’m not sure what point it was that you were making with this specific comment ... I am fully aware that the flight crew opened the engine reversers in an attempt to counter the forward thrust that idling engines would produce so that the smaller tug would have a better chance to push the airplane off of the gate and up the slight inclined that was present. That effort was not successful. The engines were shut down and a larger tug, equipped with tire chains was brought in to complete the push back.

I am also fully aware of what was said and who said it. However, you are presuming that what the F/O said had reference to an “engine anomaly.” I’m not sure what anomaly you may think he was referencing, but the fact is that for some 20 seconds both the Captain and the F/O were apparently attempting to determine what it was that was causing the F/O to say what he said. If there was an engine anomaly, it certainly wasn’t apparent to either crew member for at least that length of time. It is my opinion (and no, I can’t prove it – but it is my opinion) that the F/O was feeling something “out of sorts” and that was the position of his hand and arm when on the throttles when the engine instrument readings were apparently indicating what they should have been indicating. Only he would have had that “feeling” and the Captain would not have noticed. Muscle memory is a very important issue when accomplishing something in a routine manner. The engines were, in fact, operating just as they should have been operating – except that the PT2 probes were blocked with ice and were producing only about 75% of the takeoff power they should have been producing. With the kind of limited visibility that existed at the time, external references would have been of little or no value to assist in judging airplane acceleration.

I hope we’re not going to rehash your entire previous post ... I am fully aware of when they started their takeoff roll. 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. And, as I just pointed out to rabski, the crash was not a 1-in-3 gamble ... the crash was caused by the ice build up on the accident airplanes wings ... put there by the deicing crew when they sprayed water all over the airplane and the engines.

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!” Again, I can’t prove it – except to note the rate of climb shown on the limited Flight Data Recording at that time – but it makes sense that this comment was a result of the airplane being rotated at an unusually high rate of rotation to an unusual and abnormally high attitude – NOT by the F/O deflecting the elevator controls, but rather because of the asymmetrical longitudinal lift that was being generated because of the ice-deformed wings – again created by the deicing crew.

If what you’re concerned about was the fact that the crew elected to depart with some accumulation of snow on the wings – I’ll agree that is just what they did. Although, being able to see the wings from the cockpit is not an easy thing to do in a B-737 – where only about the outboard 10 -12 feet are typically observable from the cockpit. If you want to criticize them for taking off with whatever snow accumulated during their taxi – you would be correct and I won’t argue ... but the same thing would have to be said for Apple 58 and Six Eight Gulf. Leaving the same question ... why would only one of those three aircraft not be able to fly? And clearly, it was the inadequate and insidious deicing process this one airplane experienced – and had nothing to do with the snow that accumulated.


Mr. rabski
To the contrary ... I'm not missing any point. I know what happened and why. I fear it is you who fail to understand what happened. I am disappointed in that you absolutely refuse to understand the thought processes that were routine some 30 years ago – we used to think that asbestos was a good insulator – we used to think that cigarette smoking was a pleasant past-time – we used to think that 8 miles-per-gallon was reasonable mileage for a car – we used to think it appropriate for parents to send their kids to the park to play all by themselves – we used to think that taking off with a small amount of snow accumulation on a wing that had been recently deiced was OK (and there are some who STILL think that way – apparently including the various regulatory authorities). If you too wish to criticize that flight crew for taking off with some accumulation of snow on the wing ... be my guest. They did that. However, as I’ve been saying all along ... THAT was not the reason they crashed!

Well, in the seventies I'd left the RAF and was flying for BEA/BA and we didn't think it was OK to go with any contamination on the top of the wing.

I still think it's appropriate to send children off to play by themselves I'm afraid, but then I often find myself apart from current thinking in some cirsumstances.

However, something like 30 years ago I was doing my PPL. With an instructor, God bless him, who told me in no uncertain terms more than once that it wasn't OK to go for it if there was so much as a squashed gnat on the wing, let alone some snow.

He was qute right then and he still is now.

Whichever way you look at it, the reason for the crash was contamination on the flying surfaces, and it's been the reason for a number of fatal incidents. It wasn't permitted or excusable then, and it isn't now.

Enough lives have been lost to make this a point that never needs to be debated surely.

It's pretty simple. To begin the T/O roll, you must have a clean wing, critical surfaces, etc. that are free of frost, ice, or snow. "Clean" can include anti-ice fluid that hasn't failed/reached its saturation point. 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. If the pilot has miscalculated the precip type/intensity or other variables came into play (rapidly chancing temp/wind/jet blast) that cause visual indications the fluid has failed within the HOT, the pre-takeoff contamination check from outside the aircraft within 5 mins must still be done. When the fluid has become saturated, it's impossible for a pilot inside the aircraft to visually ascertain if there is re-freezing/adhering to the critical surfaces underneath the fluid. There are no "representative surfaces" for the contamination check, only the real ones. Since the manufacturers of fluids do not give a holdover times for heavy snow conditions, it did use to cease t/o operations because it threw Type 4 HOT tables out of whack, but now it's allowed if it's applied at 100% strength and a "definitive fluid failure determination" made within 5 minutes of takeoff.

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 be adhering somewhere...you certainly can't make a definitive determination that it isn't. If it has accumulated on the surface of de/anti-ice fluid, the fluid has failed. In either case, this "accumulation" of snow it doesn't meet the criteria "free of". It's contaminated. Period.

30 years ago was 1982. There had already been 2 oil crises, everyone knew asbestos and smoking were bad for you, 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". There's always pilots that theorize about CBs too...the "Oh that's just rain" type who once flew through the red blob of a dying airmass baby in Florida who then supposes that's what he'll find inside a steady-state Level 6 over Kansas. The same mentality that screws around with snow on the wings and red on the radar stands a good chance of pushing their own metal into the smoking hole.

Thank you Doves, I wasn't really directly speaking to you though I did quote you - it was more a general statement. Thankfully we don't get much ground icing here in Hawaii, though prior to this I was based in Spokane. I realize those of us in the US understand the standard by which aircraft are de-iced but wanted to publish the general standard for those not familiar with why we operate with a "clean wing" concept.

We often discuss how much ice is too much for take off. We determined that if there isn't enough room for at least six drinks in the cooler then we must de-ice.