I've flown a fair amount over many decades from cold weather airports and have seen deicing take place on my ride, and have always been interested in the process.
However, its only been the last few years that I've had a better grasp of the aerodynamic issues that make this a critical procedure.

Anecdotally, it seems as though in decades past, the fuselage was targeted, whereas recently, it seems only the airfoil was targeted. Perhaps this is just coincidental (more judicious use of fluid).

do the de-icing operators have any specific training? More often than not, this takes place in dark, artificially light conditions - what do the operators look for?

Pilots make standard walk-arounds prior to departure, but obviously, they do not do so after de-icing, so how is the aircraft judged to be suitably de-iced?

is the procedure different now than in decades past?

any information about this mundane, but important task is appreciated!

Cubsrule wrote:

FlyHappy wrote:

Pilots make standard walk-arounds prior to departure, but obviously, they do not do so after de-icing, so how is the aircraft judged to be suitably de-iced?

Many (most?) carriers require that pilots inspect the wings immediately pre-departure in certain types of active precipitation. It’s typically done from the cabin.

Is that right? I cannot recall having seen a pilot enter the cabin after the procedure..... (just my flawed non-memories!)

FlyHappy wrote:

Pilots make standard walk-arounds prior to departure, but obviously, they do not do so after de-icing, so how is the aircraft judged to be suitably de-iced?

Many (most?) carriers require that pilots inspect the wings immediately pre-departure in certain types of active precipitation. It’s typically done from the cabin.

FlyHappy wrote:

Anecdotally, it seems as though in decades past, the fuselage was targeted, whereas recently, it seems only the airfoil was targeted. Perhaps this is just coincidental (more judicious use of fluid).

do the de-icing operators have any specific training? More often than not, this takes place in dark, artificially light conditions - what do the operators look for?

Pilots make standard walk-arounds prior to departure, but obviously, they do not do so after de-icing, so how is the aircraft judged to be suitably de-iced?

is the procedure different now than in decades past?

any information about this mundane, but important task is appreciated!

1. In relation to what areas of the aircraft are treated, there can be no frozen contamination on the wings, tail, engines, sensors (pitot tubes, AOA vanes), and other critical surfaces per FAR. The level of treatment really depends on the type and amount of precipitation. For example, a wet heavy snow will require Type IV fluid all over while a very light flurry might call for just Type I on the wings and tail.

2. Deice personnel undergo training every year for qualification. The entire deice manual is read through and hands on training is conducted.

3. Deicers look for snow, frost, rime ice, and clear ice on the aircraft. If any of these are on a critical surface, they must be removed.

4. It is the deice personnel's responsibility to ensure that the aircraft is clean, properly treated, and safe for departure. The fluids applied have a certain amount of time (holdover time) that they will protect the aircraft. The time all depends on fluid type, precipitation type, outside air temperature, wind, etc. The flight crew has a chart to determine what the holdover is based on the atmospheric conditions. There are surfaces on the aircraft that the pilots can see from the flight deck to check for contamination after deicing in case of a longer than expected taxi, for example.

BlueLine wrote:

1. In relation to what areas of the aircraft are treated, there can be no frozen contamination on the wings, tail, engines, sensors (pitot tubes, AOA vanes), and other critical surfaces per FAR. The level of treatment really depends on the type and amount of precipitation. For example, a wet heavy snow will require Type IV fluid all over while a very light flurry might call for just Type I on the wings and tail.

2. Deice personnel undergo training every year for qualification. The entire deice manual is read through and hands on training is conducted.

3. Deicers look for snow, frost, rime ice, and clear ice on the aircraft. If any of these are on a critical surface, they must be removed.

4. It is the deice personnel's responsibility to ensure that the aircraft is clean, properly treated, and safe for departure. The fluids applied have a certain amount of time (holdover time) that they will protect the aircraft. The time all depends on fluid type, precipitation type, outside air temperature, wind, etc. The flight crew has a chart to determine what the holdover is based on the atmospheric conditions. There are surfaces on the aircraft that the pilots can see from the flight deck to check for contamination after deicing in case of a longer than expected taxi, for example.

Thank you for those details! I had to look up "rime ice" !

stupid followup questions - being that de-icing is a pretty infrequent activity in most places, what kind of personnel typically do this? As in what's their "day job"? And given that critical sensor areas must be carefully inspected, and the wide variety of aircraft at larger airports, do these manuals specifically map out all possible aircraft types, or are these things so standardized in appearance and location that they are just obvious to the deicer, regardless of type?

Most aircraft have what is called a representative surface, usually a spoiler or aileron with a high contrast, lit spot that pilots can inspect from the cockpit, for determining the surface contamination level. Flight attendants can also perform the pre takeoff contamination inspection.

FlyHappy wrote:

BlueLine wrote:

1. In relation to what areas of the aircraft are treated, there can be no frozen contamination on the wings, tail, engines, sensors (pitot tubes, AOA vanes), and other critical surfaces per FAR. The level of treatment really depends on the type and amount of precipitation. For example, a wet heavy snow will require Type IV fluid all over while a very light flurry might call for just Type I on the wings and tail.

2. Deice personnel undergo training every year for qualification. The entire deice manual is read through and hands on training is conducted.

3. Deicers look for snow, frost, rime ice, and clear ice on the aircraft. If any of these are on a critical surface, they must be removed.

4. It is the deice personnel's responsibility to ensure that the aircraft is clean, properly treated, and safe for departure. The fluids applied have a certain amount of time (holdover time) that they will protect the aircraft. The time all depends on fluid type, precipitation type, outside air temperature, wind, etc. The flight crew has a chart to determine what the holdover is based on the atmospheric conditions. There are surfaces on the aircraft that the pilots can see from the flight deck to check for contamination after deicing in case of a longer than expected taxi, for example.

Thank you for those details! I had to look up "rime ice" !

stupid followup questions - being that de-icing is a pretty infrequent activity in most places, what kind of personnel typically do this? As in what's their "day job"? And given that critical sensor areas must be carefully inspected, and the wide variety of aircraft at larger airports, do these manuals specifically map out all possible aircraft types, or are these things so standardized in appearance and location that they are just obvious to the deicer, regardless of type?

Usually they are regular rampers with additional training. I've seen a few places where the deicing team is a separate division (there are also companies that offer only deicing) and the deicers will sit in a break room all day, whether or not they have to spray. Flip side is, during a deicing event they may work 20+ hours non-stop.

Usually the supervisors will have access to specific aircraft info, and can direct the deicers. During training they will cover what to look for though.

And to touch upon how the crew knows the airplane is ready, usually the lead or supervisor will give them a run down of what happened. (Aircraft deiced, types I and IV. Start time xx:xx, completed at xx:xx. All equipment is clear of aircraft, please contact ground at xxx.xxx for taxi instructions.) Or some combination of into similar

whywhyzee wrote:

Most aircraft have what is called a representative surface, usually a spoiler or aileron with a high contrast, lit spot that pilots can inspect from the cockpit, for determining the surface contamination level. Flight attendants can also perform the pre takeoff contamination inspection.

ahhhhhh.... most interesting. I believe I have seen those illuminated spots from time to time (gets very prominent in a snowstorm) and wondered what the purpose was!

There are “holdover” tables the crew uses to consider the length of time from the begin of driving to latest allowable take-off time, depending on fluid used, type and intensity of precipitation; and OAT for the major factors. Once “times up”; it’s another de-icing.

GF

FlyHappy wrote:

Cubsrule wrote:

FlyHappy wrote:

Pilots make standard walk-arounds prior to departure, but obviously, they do not do so after de-icing, so how is the aircraft judged to be suitably de-iced?

Many (most?) carriers require that pilots inspect the wings immediately pre-departure in certain types of active precipitation. It’s typically done from the cabin.

Is that right? I cannot recall having seen a pilot enter the cabin after the procedure..... (just my flawed non-memories!)

It’s not common. At DL, I know it requires heavy falling snow and may not be on all types.

whywhyzee wrote:

Most aircraft have what is called a representative surface, usually a spoiler or aileron with a high contrast, lit spot that pilots can inspect from the cockpit, for determining the surface contamination level. Flight attendants can also perform the pre takeoff contamination inspection.

Flight attendants CANNOT perform a PCI. They are not trained in such.

Here's something you will never hear from a Captain, "Well the flight attendant said it looked ok so we went flying".

There are various "threshold times".

Example: You de-ice and anti-ice. The appropriate table for fluid and conditions has two times, a lower and a higher. At the start of the last application of fluid, the clock starts ticking. If take-off is before the lower time, no inspection is needed. If after the lower time but before the higher time a visual inspection from the cabin is needed. After the higher time an inspection by an engineer outside is needed.

pikachu wrote:

whywhyzee wrote:

Most aircraft have what is called a representative surface, usually a spoiler or aileron with a high contrast, lit spot that pilots can inspect from the cockpit, for determining the surface contamination level. Flight attendants can also perform the pre takeoff contamination inspection.

Flight attendants CANNOT perform a PCI. They are not trained in such.

Here's something you will never hear from a Captain, "Well the flight attendant said it looked ok so we went flying".

Indeed.

Google the following reference guide>

120-58 - Pilot Guide Large Aircraft Ground Deicing

This will answer most, if not all your questions regarding this subject.

Anecdotally, it seems as though in decades past, the fuselage was targeted, whereas recently, it seems only the airfoil was targeted. Perhaps this is just coincidental (more judicious use of fluid).

The top of the fuselage needs deicing mostly with rear engined aircraft. DC9 B727 Tristar and DC10 all needed a clean fuselage to stop snow entering the engines.
As these types have disappeared, much less is done. We still deice the fuselage, even on B737 and A320, just not as often. You know when the fuselage is being deiced, it gets very noisy in the cabin.

FlyHappy wrote:

stupid followup questions - being that de-icing is a pretty infrequent activity in most places, what kind of personnel typically do this? As in what's their "day job"?

Out of curiosity I asked this same question some years ago and learned that the vendor for my former carrier had hired quite a few area farmers - it's a slow time of year for them and the ramp agents were already stretched tight in numbers doing their regular duties. But I suspect it's a different answer at other hubs.

Many (most?) carriers require that pilots inspect the wings immediately pre-departure in certain types of active precipitation. It’s typically done from the cabin.

I'm a pilot for a large European legacy, never heard of such a procedure nor have I ever seen anybody do it...
After the de/anti-icing crew is finished with the job their supervisor will do a "clean-wing check", after he/she has done that they will give us the de/anti-icing code with all the relevant information.

Usually the decision making will go as follows:
Scenario is -SN, temperature -3°C. Captain and I see that some snow has accumulated on the aircraft during turn-around. Usually it will just be couple millimeters. As snowfall is still ongoing we decide for a "two step procedure". First step de-icing, using Type I fluid to remove the snow. Second step anti-icing, Type II or IV fluid which have a much higher holdover times, to give us enough protection from new snow between anti-icing and departure. A little snow on the fuselage doesn't hurt, so it will usually not be removed. If the aircraft was parked over night and like 10 centimeters of snow are on the aircraft, of course it will be removed.
Now we meet the de-icing crew (either via radio if done on a remote position or in person if done on stand) and they will give us the latest weather update and what treatment they would suggest for the current situation. Usually their and our idea is the same. We then go ahead and de/anti-ice the aircraft. After that we receive the aforementioned de/anti-icing-code, which will be something like: "Aircraft de/anti-iced, two step procedure, second step performed with Type IV fluid 'brand name' 75%, start second step at 1306 local time, clean-wing check performed". Captain then enters type and percentage of treatment together with the start time converted to UTC in the aircraft log. From that time onwards the holdover time counts. Before the actual departure we will take look at the wing from our seats if anything has formed again on the reading edge of the airfoil. But most of the time we have like 30+ minutes holdover time and less than 10 minutes from anti-icing to departure, so there should never be anything.

For example, a wet heavy snow will require Type IV fluid all over while a very light flurry might call for just Type I on the wings and tail.

Not correct. The difference between Type I and Type IV fluid is the holdover time only. If lots of snow has accumulated on the airframe over night but the weather is gone now and it's clear skies, then Type I is sufficient. Type I removes the deposits just as well (if not even better) then Type IV fluid does. Plus it doesn't gum up the movable parts of your wing like ailerons, which is a concern on aircraft with non-powered flight controls such as Dash-8s, AVROs, CRJs and so on.

If after the lower time but before the higher time a visual inspection from the cabin is needed. After the higher time an inspection by an engineer outside is needed.

At least in Europe I've never heard of such a thing. The lower limit is for moderate intensity (moderate snow, moderate freezing fog and so on) the higher limit for light intensity. Which one applies is depending on ATIS and the pilots judgment. Latest at the later limit a new de/anti-icing is required, or as soon as any deposits starts forming on the treated surfaces again. But in any case, it's only a holdover-time guideline. So it's not necessarily correct in all cases, the final decision on whether or not the aircraft is airworthy rests with the commander. If there is any doubt, it's another round of de/anti-icing.

Greets,
T1a

If you had taken the time it took you to type this post and instead read the Advisor Circular you would have seen where information lives>

I'm sorry, but I've never even heard of an Advisor Circular, nor do I know what that is. May be some FAA terminology/thing I'm not familiar with... Either way, my company specifically designs a computer-based training for pilots to click through every year before the icing-season starts. Afterwards I have to take a test on it, so I believe if there was such a procedure at my company, I would know about it. At my company all pilots keep current based on the CBTs provided by the employer; I don't usually read stuff published by the authority, and I don't know many colleagues that do.

And I checked, an Advisory Circular is really a FAA thing. The next time please keep in mind that not everybody on this forum lives in the US and is governed by the FAA. There are plenty of differences between FAA and EASA regulations and obviously this wing-check from the cabin is one of them.

Greets,
T1a

T1a wrote:

And I checked, an Advisory Circular is really a FAA thing. The next time please keep in mind that not everybody on this forum lives in the US and is governed by the FAA. There are plenty of differences between FAA and EASA regulations and obviously this wing-check from the cabin is one of them.

Greets,
T1a

You are correct and I'm keenly aware of the issues as I work closely with EASA regulators every day.

Cheers:)

T1a wrote:

If after the lower time but before the higher time a visual inspection from the cabin is needed. After the higher time an inspection by an engineer outside is needed.

At least in Europe I've never heard of such a thing. The lower limit is for moderate intensity (moderate snow, moderate freezing fog and so on) the higher limit for light intensity. Which one applies is depending on ATIS and the pilots judgment. Latest at the later limit a new de/anti-icing is required, or as soon as any deposits starts forming on the treated surfaces again. But in any case, it's only a holdover-time guideline. So it's not necessarily correct in all cases, the final decision on whether or not the aircraft is airworthy rests with the commander. If there is any doubt, it's another round of de/anti-icing.

Greets,
T1a

As you say the lower holdover time is for moderate intensity and the higher one for light intensity. At my operator the requirement for an inspection is as I stated. Operator specific I guess.

Reading the Transport Canada Holdover Time Guidelines (http://176.62.164.158/tables/HOT_Guidel ... iginal.pdf) it says The only acceptable decision-making criterion, for takeoff without a pre-takeoff contamination inspection, is the shorter time within the applicable table cell.

And indeed the times are "guidelines". Quoting the Transport Canada document again: The time of protection will be shortened in heavy weather conditions, heavy precipitation rates, or high moisture content. High wind velocity or jet blast may reduce holdover time below the lowest time stated in the range. Holdover time may be reduced when aircraft skin temperature is lower than outside air temperature.

T1a wrote:

Plus it doesn't gum up the movable parts of your wing like ailerons, which is a concern on aircraft with non-powered flight controls such as Dash-8s, AVROs, CRJs and so on.

Thanks for the very detailed answer, and I'm amazed that those aircraft have non-powered flight controls.... I had no idea!

FlyHappy wrote:

T1a wrote:

Plus it doesn't gum up the movable parts of your wing like ailerons, which is a concern on aircraft with non-powered flight controls such as Dash-8s, AVROs, CRJs and so on.

Thanks for the very detailed answer, and I'm amazed that those aircraft have non-powered flight controls.... I had no idea!

Even the DC-9/MD-80 family has non-powered flight controls. Control tabs are powerful things.

Starlionblue wrote:

Even the DC-9/MD-80 family has non-powered flight controls. Control tabs are powerful things.

Okay - wow.
You've made look look up "servo tab" and get a brief lesson on geared, spring, anti, etc....... I need a drink.....
( you did originally type "servo tab", no?)

FlyHappy wrote:

Starlionblue wrote:

Even the DC-9/MD-80 family has non-powered flight controls. Control tabs are powerful things.

Okay - wow.
You've made look look up "servo tab" and get a brief lesson on geared, spring, anti, etc....... I need a drink.....
( you did originally type "servo tab", no?)

Yes. Servo tab, control tab, balance tab. Lots of tabs.

In larger planes its just brute force hydraulics though. Lots and lots of brute force.

BravoOne wrote:

T1a wrote:

And I checked, an Advisory Circular is really a FAA thing. The next time please keep in mind that not everybody on this forum lives in the US and is governed by the FAA. There are plenty of differences between FAA and EASA regulations and obviously this wing-check from the cabin is one of them.

Greets,
T1a

You are correct and I'm keenly aware of the issues as I work closely with EASA regulators every day.

Cheers:)

Maybe we should have a policy that the OP identifies which regulatory authority he/she is posting under so we don't have these understandings in the future. I naturally thought the OP was asking an FAA oriented question, when it could have been EASA, FAA, CAA, JAA or simply an "aligned" authority. That way everyone's pride is not offended?

Well, you and I could adhere to such a policy, but I'm not sure a large percentage of the forum users will/can. There is a lot of non-professionals here, which is a good thing, but at the same time they probably have no idea that the question they ask may be answered differently in different parts of the world due to different regulatory bodies.
As long as we keep having "Why not re-engine the B757" threads, I'm pretty sure a detailed policy like that will most likely fail
But I completely agree with you, it would definitely help. That's why I stated where I work, so people can see how it's done here; and that is why I was a little surprised when you threw the AC thing at me...

Anyway, cheers!

The Advisory Circulars are in many cases the bible from which the FAA oversight is drien. Things like ETOPS, Low Viz, etc. all come from AC;s. They are not 'regulatory" in and of themselves but give guidance,

FlyHappy wrote:

stupid followup questions - being that de-icing is a pretty infrequent activity in most places, what kind of personnel typically do this? As in what's their "day job"? And given that critical sensor areas must be carefully inspected, and the wide variety of aircraft at larger airports, do these manuals specifically map out all possible aircraft types, or are these things so standardized in appearance and location that they are just obvious to the deicer, regardless of type?

It depends on the station - at the outstations, deicing can be subcontracted out to the FBO or the station can have its own deicing trained personnel which will just be "just-one-more-thing" duty for the rampers who already do everything else.

At my first airline, at the outstations there was only one employee who did everything during for the turns. The deicer was also the station's one full time employee / station manager / ticketing agent / ramp agent / do everything employee.

Woodreau wrote:

At my first airline, at the outstations there was only one employee who did everything during for the turns. The deicer was also the station's one full time employee / station manager / ticketing agent / ramp agent / do everything employee.

haha! I was once at a small airport in the Bahamas where I watched a young guy marshall the plane in, unload the bags onto a tug, drive it in, unload again, fuel the aircraft (I think), enter the aircraft (clean the lav?) and other such insanity.
But your guy might have him beat if he was doing that in cold weather and had to de-ice. Amazing!

BravoOne wrote:

Maybe we should have a policy that the OP identifies which regulatory authority he/she is posting under so we don't have these understandings in the future. I naturally thought the OP was asking an FAA oriented question, when it could have been EASA, FAA, CAA, JAA or simply an "aligned" authority. That way everyone's pride is not offended?

ehhhhhhh.... for what little its worth, as the OP who knows very, very little about aerodynamics or flight ops, my experiences are pretty broad, having spent a lifetime being de-iced in Asia, US, and Europe
So, the last thing I was thinking was to specify any specific regulatory body!

But I truly thank all of the expert comments contributed. As annoying as parts of A.net can be, its the small things that are valued. I cannot really just google a procedure like this and read a technical bulletin and hope to understand it directly. Sometimes there's just no substitute for "question and answer".

Sorry brought the subject up. Didn't mean to start a kerfuffle:)

BravoOne wrote:

The Advisory Circulars are in many cases the bible from which the FAA oversight is drien. Things like ETOPS, Low Viz, etc. all come from AC;s. They are not 'regulatory" in and of themselves but give guidance,

Of course, nothing permits an operator from having more stringent rules than what the FAA (or any other regulator) recommends or requires. My sense is that some do on de- and anti-icing, just like in a plethora of other areas. And at least in the States, if it's in the Ops Specs, it's effectively a regulatory requirement applying to the carrier in question.

Starlionblue wrote:

FlyHappy wrote:

T1a wrote:

Plus it doesn't gum up the movable parts of your wing like ailerons, which is a concern on aircraft with non-powered flight controls such as Dash-8s, AVROs, CRJs and so on.

Thanks for the very detailed answer, and I'm amazed that those aircraft have non-powered flight controls.... I had no idea!

Even the DC-9/MD-80 family has non-powered flight controls. Control tabs are powerful things.

So do 707s. Until they made the tails higher, it was all manual. They say the 707 flew like a truck, and the 727 flew like a sportscar (Boeing got a retired Lockheed engineer to un-retire and do the 727 hydraulics).

Cubsrule wrote:

Of course, nothing permits...

Prevents?

LH707330 wrote:

Cubsrule wrote:

Of course, nothing permits...

Prevents?

Derp. Yes, indeed.

[
So do 707s. Until they made the tails higher, it was all manual. They say the 707 flew like a truck, and the 727 flew like a sportscar (Boeing got a retired Lockheed engineer to un-retire and do the 727 hydraulics).

Pretty sure the rudder was boosted from the get go on the 707, and while it was heavier than the 727, it was not a truck by any means. One hand worked just fine.

BravoOne wrote:

[
So do 707s. Until they made the tails higher, it was all manual. They say the 707 flew like a truck, and the 727 flew like a sportscar (Boeing got a retired Lockheed engineer to un-retire and do the 727 hydraulics).

Pretty sure the rudder was boosted from the get go on the 707, and while it was heavier than the 727, it was not a truck by any means. One hand worked just fine.

Hmm, I think you might be right, I thought it was added later. http://www.adastron.com/707/qantas/Q-bellows.htm

Thanks for posting that reference. Better than most Boeing manuals on the subject. FWIW, VMCA was around 185Kts with the rudder boost off, thus making it hazardous to you're safety of flight should it fail, or be turned off at the overhead panel.