WJ's not so squeaky clean

[Guest rattler]

found on another site, the restriction re ambient air is interesting.....

From Boeing Volume 1, B737-700 Supplementary Procedures section 3.

'Takeoff with light coatings of cold soaked fuel frost on upper wing surfaces is permissible, provided the following conditions are met:

The frost is less than 1.5mm thickness

The extent of the frost is similar on both wings

The frost is within the black lines denoted on figure (basically inboard half of the wing, well away from both leading and trailing edges)

Ambient air temp is above freezing

There is no precipitation or visible moisture

If all above criteria are not met, all ice or frost on the wings must be removed.

[Canus Chinookus]

now all we need is certification to depart with trace icing on the leading edges of the wings. It would be nice to see a return to common sense regarding ice.

ps. I'm told boeing actually flew a 737 around with a 2X4 attached to the leading edge of the horizontal stab with no adverse flight characteristics.

[handyman]

now all we need is certification to depart with trace icing on the leading edges of the wings. It would be nice to see a return to common sense regarding ice.

ps. I'm told boeing actually flew a 737 around with a 2X4 attached to the leading edge of the horizontal stab with no adverse flight characteristics.

I'm sure you hear lots of things on the line...doesn't mean they are true!

[Spinnaker]

now all we need is certification to depart with trace icing on the leading edges of the wings. It would be nice to see a return to common sense regarding ice.

ps. I'm told boeing actually flew a 737 around with a 2X4 attached to the leading edge of the horizontal stab with no adverse flight characteristics.

I'm not for pilots and common sense. This is a giant leap allowing fuel frost and could be taken away at the first sign of abuse. If any amonut of ice accumulation starts being left to the PIC again then Dryden could happen all over again. Spraying, and the strict rules, are just a cost of doing business IMO.

[Guest Kilo Mike]

Spraying, and the strict rules, are just a cost of doing business IMO.

Exactly !! Why is it even being looked at as a cost saver? Next thing you have is an "interpretation" of whats "a little" frost and Whamo. We end up having a new version of an old leason.

It's cut and dry ... A clean wing period. Not some quasie touchie feelie rule, or exemption. The fact that the determination of an ice accumulation 's thickness is hap-hazard at best, why even tempt fate or allow it to be tempted?

[E-HANDLE]

Hey KM,

Boeing did the flight testing, the FAA and TC did the approving. Now, to me, the limitations and procedures are quite clear. Is it safe or not? The manufacturer and regulators say it is. If you think you know better than them, well, that's up to you.

If you don't like touchy feely exemptions, why not rail against 1 in 50 on AC RJs and Dashs?

[Guest Kilo Mike]

Hi E-handle.

It's this stuff that makes my spidey sense stand up:

The frost is less than 1.5mm thickness

The extent of the frost is similar on both wings

Are you telling me in a quick turn that someone from the flt crew is going to go out and ensure the thickness is measured and confirmed? If so, then I guess it's OK . I challenge you to tell me that in one of your quick turns, this doesn't open the door a crack for 'interpretation" and as such creates the first hole in the accident swiss cheese model.

What does similar mean when it comes to wing coverage?

Does the thickness have to be uniform?

How is it measured?

Does the frost have to be all the same?

What about the very hard to see clear ice that can form on cold soaked wings?

I think you get my point here.

[E-HANDLE]

Hi E-handle.

It's this stuff that makes my spidey sense stand up:

The frost is less than 1.5mm thickness

The extent of the frost is similar on both wings

Are you telling me in a quick turn that someone from the flt crew is going to go out and ensure the thickness is measured and confirmed? If so, then I guess it's OK . I challenge you to tell me that in one of your quick turns, this doesn't open the door a crack for 'interpretation" and as such creates the first hole in the accident swiss cheese model.

What does similar mean when it comes to wing coverage?

Does the thickness have to be uniform?

How is it measured?

Does the frost have to be all the same?

What about the very hard to see clear ice that can form on cold soaked wings?

I think you get my point here.

If you aren't sure, then you get sprayed.

And yes, someone from the flight crew will check thoroughly. On my crew, that someone is me. If the turn doesn't allow enough time for a thorough inspection, then the turn gets longer. If I can't be absolutley sure that all the perameters are met, then I get sprayed.

I can remember a few years ago, on the old forum, getting into an argument about spraying the tanks on the 737-200 because of ice in YVR. People laughed at us, told us there could be no ice at +10C. But it there was. I know, I would get up on a ladder myself and check.

Just like I'm gonna check now.

[J.O.]

What does similar mean when it comes to wing coverage?

Does the thickness have to be uniform?

How is it measured?

Does the frost have to be all the same?

What about the very hard to see clear ice that can form on cold soaked wings?

Well said, KM. I cannot for the life of me understand why Boeing would go to the trouble of testing this in the first place. In an industry where we've finally accepted that clean is green when it comes to wing contamination, it's a huge step backwards to open the door to going flying with contamination on the critical surfaces. And the bit about the deicing fluid doing more to destroy lift than frost is hogwash. It's a fluid, and it will flow away before safe flying speed. Frost won't do that. Given that one of the acceptance conditions is a temperature above freezing, there's also the cooling dynamics of the air as it flows over the wing, causing a contaminant which may be melting to re-freeze.

[Guest Kilo Mike]

Hi E-Handle.

Please understand I'm not saying "you" wouldn't get sprayed. I'm talking about the concept that spraying becomes a matter of interpretation. It's this part that I think is a step in the wrong direction. You seem like a thorough type person, as I like to consider myself to be. Can you say that every other pilot out there is as thorough? -vanity aside

I think we've both been around the patch enough to know the answer to that one.

[AIP]

Well said, KM. I cannot for the life of me understand why Boeing would go to the trouble of testing this in the first place. In an industry where we've finally accepted that clean is green when it comes to wing contamination, it's a huge step backwards to open the door to going flying with contamination on the critical surfaces. And the bit about the deicing fluid doing more to destroy lift than frost is hogwash. It's a fluid, and it will flow away before safe flying speed. Frost won't do that. Given that one of the acceptance conditions is a temperature above freezing, there's also the cooling dynamics of the air as it flows over the wing, causing a contaminant which may be melting to re-freeze.

Good Post J.O.

I too was shocked at this development and after Dryden find it amazing that TC would go for it, but a good lobbyist gets things done. Also suprised at the level of excuses to validate this (fluid being a contaminant).

Sadly in today's environment, cost cutting is the only important thing. Keeping the CASM (or whatever value is the flavour of the day) seems to be ahead of most everything else.

Be careful boys and girls.

[Fido]

....It's a fluid, and it will flow away before safe flying speed. ....

It doesn't. It is a sticky goey mess that you would not want to get on your nice clean flying suit even after a trip from YVR to YYC. Have look and run your hand over a wing surface that was sprayed at the previous station.

[E-HANDLE]

Good Post J.O.

I too was shocked at this development and after Dryden find it amazing that TC would go for it, but a good lobbyist gets things done. Also suprised at the level of excuses to validate this (fluid being a contaminant).

Sadly in today's environment, cost cutting is the only important thing. Keeping the CASM (or whatever value is the flavour of the day) seems to be ahead of most everything else.

Be careful boys and girls.

Are you saying that Boeing, the FAA and TC are pulling the wool over peoples eyes because they were lobbied to do so? That the flight testing was flawed?

Every day that we go out in an airplane, we operate on certain assumptions. That the runway distance specified in the AFM really is adequate, as the manufacturer has certified. That the airplane really will fly away on one engine, with the reqired gradient, because the AFM says so.

Now, after the flight testing and certification has proved that the aircraft will fly as expected with a small amount of tank frost, should I disregard the process that is the basis of transport flying?

[Vsplat]

Man, what a mess.

I will be blunt.

De-icing fluid reduces lift. It is a calibrated risk and no, it does not all flow away, not even Type I. Sorry J.O., it isn't hogwash, it is physics.

De-icing fluid is better than a contaminated wing in most cases because the contamination kills lift in unpredictable ways. Spraying a clean wing, or a very cold, dry wing in cold, dry, non-adhering snow is a bad idea, as you are taking a peformance hit for nothing.

I say most caes, because there are two exceptions: the common, under-wing case and Boeing's singular work on the 737-NG. Other manufacturers are studying similar relief and it is under discussion at SAE.

The reason for Boeing's work is because the NG wing promotes fuel soak frost far more than others. The original customers were demanding support because they operate to many stations that have no de-icing capability. Nor is it needed in this case, as the flight test program validated boundary layer characteristics with this type of frost.

And it wasn't the lobbyists. This was done by the technical staff.

BTW frost is not one contaminant, it is a group of related phenomena. Hoar frost on the fuselage thin enough to see through has a particular makeup and bonding that makes it a non-threat for engine FOD. The fuel-soak frost in the Boeing case has to remain within the parameters for the supplement (it is not an exemption at the root of this). Frost that goes outside of any of the limitations is not the same type and a very different risk case.

Anyone who thinks trace ice on the leading edge should be allowed one day as 'comon sense' needs to consider the aerodynamics a bit more. That is the one area that can't be messed with, slats or no. If you don't establish the flow properly, all bets are off.

There is a ton of opinion being submitted here as fact. This is not a good topic for that. I strongly suggest that folks check their company material and verify what they are saying before putting it down here. Remember, some of those on the forum are in the early stages of their career and are flying single pilot. The wrong impression about 'a little ice' might go a long way, the wrong way.

Vs

[AIP]

Are you saying that Boeing, the FAA and TC are pulling the wool over peoples eyes because they were lobbied to do so? That the flight testing was flawed?

Every day that we go out in an airplane, we operate on certain assumptions. That the runway distance specified in the AFM really is adequate, as the manufacturer has certified. That the airplane really will fly away on one engine, with the reqired gradient, because the AFM says so.

Now, after the flight testing and certification has proved that the aircraft will fly as expected with a small amount of tank frost, should I disregard the process that is the basis of transport flying?

What I am saying, is Boeing just did not decide to do this of their own accord. The idea had to come from somewhere.

1.5 mm is OK, what about 1.6 or 1.7 ? ? Hard to tell sometimes, wouldn't it be ?? As pointed out earlier what about uniformity ??

I believe if you have to get up their with your ruler, and have a real close look at it, MY choice would be to spray EVERYTIME.

Another issue not yet debated here is what about the optics of it all ?? The gray haired gent seated in 12A watching all this unfold outside his window would surley be wondering what was going on if the Captain or his designate is up on the wing, only to decide it is "only a little bit and within limits, we can go".

Vsplat, a very good point on the context of comments made here. As always, they should be taken with a great deal of salt in my mind. And as we know all to well the typed "word" sometimes loses the meaning in which it is meant to be conveyed.

[J.O.]

I've done dozens (maybe hundreds, who counts any more) of takeoffs with deicing fluid on the wings, with nary a problem. I've also read many accident reports where frost on an uncleaned aircraft has been a causal factor. That makes the decision pretty simple for me.

I accept that Boeing flight tested it and came up with guidance material. If the situation presents itself that no fluid is available (the reason the exemption was requested in the first place), then I could see the operator allowing the flight to depart (with a few additional stipulations, such as no reduced thrust takeoffs). What I am curious about is that it's allowed when deicing fluid is available at the departure airport. As AIP said, the optics would make me uncomfortable if I was the Captain. The frequent traveler has probably heard the Captain make the "we'll be deicing" announcement several times. How comfortable will they feel on the day when they look out the window and see frost on the wing? I know I wouldn't, even now that I know this exemption is out there.

[CanadaEH]

I can remember a few years ago, on the old forum, getting into an argument about spraying the tanks on the 737-200 because of ice in YVR. People laughed at us, told us there could be no ice at +10C. But it there was. I know, I would get up on a ladder myself and check.

I laughed at you. No, I got mad at you because I was the guy deicing you in +10C in my t-shirt while every other airline came and went without a problem.

[Moon The Loon]

I've done dozens (maybe hundreds, who counts any more) of takeoffs with deicing fluid on the wings, with nary a problem.

Sorry to clip the rest of your post, but what's left quoted is an anthem to accident investigation. Dryden in particular: "I've gotten away with it before...Why should I be blamed for it on this occasion?"

[Guest rattler]

As a passenger and relating to my recent trip from YYC. Our flight was delayed for 14 mins (mostly made up in flight) as AC was doing a light spray of all of their aircraft departing at that hour (10:15) am to remove frost (Clear sky - 7C) ...... and you know, a delay for that reason did not bother me at all!!!

[boestar]

Boeing, Bombardier and Aerospatiele (sp?) have all done testing (and I am sure others as well) with simulated accumulations of ice on the wings of their respective aircraft. The tests are not done to say "look at us we can fly with ice on the wings" but to say that if there happens to be a failure of the aircraft anti ice systems that the aircraft could conceivably penetrate icing conditions and make a successful landing despite contamination.

I remember a few years back Boeing doing tests with a 737 following another aircraft in flight which was spraying a substance that would freeze on the wings with a yellow colour so as to be visable. The aircraft picked up LOTS of ice before losing stability. The ice was shed by the onboard anti icing equipment (TAI).

I am not saying anything about flying with ice in normal operation as that is ALWAYS a bad idea.

I have seen ice 1/4 inch thick on the underside of a 727 wing on a 30 deg C day in August. The planes do not de ice for this.

The limits in the FAA approval include the above 0 temperatures as the frost will diddipate from the wing as the aircraft moves through the air. Much like when you spray your windshield on a cld morning. It freezes then dries up. It dries faster the faster you go. The frost on the wings does the same thing.

I STILL BELIEVE THE CLEAN WING CONCEPT IS THE BEST AND SAFEST WAY TO GO. THERE IS NO COST TOO HIGH FOR SAFETY.

B

[Ex 9A Guy]

'Takeoff with light coatings of cold soaked fuel frost on upper wing surfaces is permissible, provided the following conditions are met:

The frost is less than 1.5mm thickness

The extent of the frost is similar on both wings

The frost is within the black lines denoted on figure (basically inboard half of the wing, well away from both leading and trailing edges)

Ambient air temp is above freezing

There is no precipitation or visible moisture

Have a good look at the conditions that must be adhered to. Some above suggested that clear ice that can form on the upper surface of the wing can be very hard to detect, I agree, but you cannot get clear ice without precipitation falling or at least visible moisture.

This phenomenom (upper surface fuel frost) has been ignored in the US for a very long time.

WJ started to encounter this when we started going to L.A. on a regular basis. After a few hours at altitude and starting out with fuel well below freezing and then landing in the humid air on the west coast we found significant fuel frost occurring. When we inquired about de-icing we were met with a blank stare. I am sure there is probably an old de-ice truck hanging around LAX somewhere but it would probably be sometime in the next millenium before it was functional.

The effects of this have been managed for the most part by planning to land with an amount of fuel in the tanks sufficient for all legalities but not tankering any excess fuel and then filling up with warm ground fuel. However sometimes this is not sufficient. The issue with the NG is the wing design, it is thinner and has a larger planform area than previous 737s and while this is great at 410 it means that even with relatively small amounts of fuel in the tanks there is a lot of fuel coming in contact with the upper wing surface. Hence the fuel frost.

Another factor that contributed to WJ investigating this was the procedures at some of our countries large airports. In YYZ you can do a frost spray at the gate for a headstart flight but for a through/connecting flight you have to go to the central delay facility. Granted it is not that busy since 737NGs are to only ones there but it does become tiresome and costly when there is a minimum charge just to enter the CDF and the nozzles only seem to come with 2 settings OFF and FULL BLAST. The FULL BLAST setting is a little overkill for 1/8 inch of fuel frost.

I understand that due to different wing and fuel tank design this is not as much of a problem on the A32X series.