on flying with polished ice on your wing [Archive]

Grunf

12th Oct 2006, 21:19

Hello all.

FAA today published a SAFO on icing for Part 91, 125 and 135 operators.

Basically it is about possiblity of taking off with polished frosting on the wings or control surfaces (currently still allowed:eek: ).

To see more of it, here is the link (http://www.faa.gov/other_visit/aviation_industry/airline_operators/airline_safety/safo/all_safos/media/2006/safo06014.pdf).

Since I have worked at several OEMs on closely related problems I can safely say that this is the biggest no-no, from ANY point of view. Sadly from what we've seen in the last 10 years there exist a bunch of people (mostly bizjet crowd) willing to take off with accumulated ice (mostly overnight) or without anti-icing on.

Please take care and do have it (a-i) on before take-off anyway since the price can be too big.

The drop in lift is so large and the airflow is so screwed up with only few traces of ice that you really need to be very, very lucky in order to take off like this and survive.

By the way - polished icing - I mean really...:= := :=

Never, never consider flying with polished ice. That is why there is a hefty a-i system installed.

Cheers

doubleu-anker

12th Oct 2006, 22:03

Attempting to get airbourne with any contamination on the flying surfaces on an aircraft, you become a "test pilot". Aviation and aerodynamics are a highly developed science. Don't pioneer.

vapilot2004

12th Oct 2006, 23:44

Attempting to get airbourne with any contamination on the flying surfaces on an aircraft, you become a "test pilot". Aviation and aerodynamics are a highly developed science. Don't pioneer.

Yes indeed. Those guys get blow-able hatches and wear parachutes. :ok:

Carnage Matey!

13th Oct 2006, 00:38

I wonder what these (http://www.aaib.dft.gov.uk/cms_resources/dft_avsafety_pdf_503172.pdf#search=%22aaib%20challenger%20cr ash%20report%20birmingham%22) guys would say about that if they were still around.

pstaney

13th Oct 2006, 11:38

Mad (Flt) Scientist

15th Oct 2006, 15:22

If there's a section of wet snow on part of your wing under that dry snow, which your quick "flick test" didn't (and probably can't) find, there may be two consequences:

1. you'll stall, crash and die
2. your obituary will blame you for the crash

pstaney

15th Oct 2006, 16:00

No doubt a disticnt possibility, and for sure been done already. The horizontal stab can't even be reached in many cases to confirm it's condition. The reasoning has been the wings appear clear, so the tail must be too... Worked last time...

I only bring this up because a "tactile" hands on inspection by the crew can be anything from a detailed sweep of the entire surfaces using ladders etc, to a quick flick with the fingers. Seen it.

Smudger

16th Oct 2006, 18:02

Jesus Christ, I can't believe I'm reading some of this stuff. If there is any doubt, THERE IS NO DOUBT, GET THE THING COMPLETELY DE-ICED. If you can't get it de-iced, DON'T GO. Get it now???? What frightens me is one day I might be a passenger with one of these pr***s up front.. I need a drink.

742

16th Oct 2006, 18:26

I've seen in FAR 91 type flying the practice of accepting loose snow on the wing, believe it will always blow off on take off. May be true in cases of dry snow, I'm not so sure that when it gets a bit wet, or sticky, this will happen. So I've found that blowing gently on the snow on the wing, or just flicking it with a finger, seems to be the sensible test. If it readily repositions itself well away or completely off the wing, seems sensible to take off. If it at all just moves over a bit, and stops, then it filts definition of adhering.

The wording of the FAR addresses snow "adhering" to the wing. Has there been any clarification on exactly what adhering has meant?

Before anyone jumps in admonishing me for not using common sense, I only pose the question because I KNOW pilots different opinions on what adhering is meant to imply.

Twenty years ago a Chief Pilot of mine killed himself one night doing this. Ironically after warning us young’ns not to do it.

Yea, the snow will probably blow off. And in his case it did. Just not symmetrically. He died when the airplane violently rolled after rotation.

The only time this "adhering" argument has any reason to even exist is in very, very light snow in very, very cold temperatures when wind is keeping anything from accumulating. In other words, when the airplane is clean.

cwatters

16th Oct 2006, 18:41

I've seen in FAR 91 type flying the practice of accepting loose snow on the wing, believe it will always blow off on take off.

...and who knows what you will find under the snow.

I've done a bit of gliding and one of the planes at our club was iffy if the wings were wet. The "stall speed wings wet" was only a few k below the normal winching speed. The field bus carried several car wiper blades and some cloths to save your life with.

Grunf

16th Oct 2006, 23:35

Ok, I guess my general point was meant for those in FAR 91 and other categories that are not obliged to turn on the anti icing "on".

Apparently guys in England (Birmingham, Challenger accident) did not do it. And they are not alone in not doing it.

It is not about flying in "known icing conditions" - it is about leaving you a/c small as a GA or as big as GV, Global or Challenger out on a tarmac overnight.

The icing on the cake can be so smooth you don't feel it.

If the OEM gave you already a hefty blow torch in form of the anti icing (believe me, I've seen burned ribs on Challengers!) you better use it.

Res ipsa loquitur

punkalouver

17th Oct 2006, 01:01

It is really just a matter of using common sense and knowing your aircraft. Sometimes you can't get every last millimeter of frost off your critical surfaces. If you are in an F-28 or baby DC-9, you never screw around with contamination. If you are on a Twin Otter lightly loaded, with other considerations taken into account, you may decide to go. I did.

742

17th Oct 2006, 01:12

punkalouver

17th Oct 2006, 03:08

The Twin Otter has been known to pitch down viciously with flaps extended past 10 and ice on the tail.

Glad that it worked out for you that time.

That is correct.....for inflight icing on the leading edge of the horizontal stabilizer. But it is difficult to apply deice fluid for this situation prior to landing. However I have yet to hear about a bit of frost doing this on takeoff. Once again, knowledge about your aircraft.
Always good to remove what you can but scraping with a broom will leave some frost residue and there could be a little bit on the vertical tail. Should I cancel the flight? Unfortunately no deice fluid is available in most arctic locations. Or the Antarctic as well from what I remember. People make posts like every location where aircraft fly is a major airport.
There is a reason why the FAA allows polished frost. Because, for example, in places like much of Alaska and similar locations you are in a small plane in the middle of nowhere where there are no de-ice facilities. There is a whole other world out there from operation on a 742. Of course you get the idiots who take things to the extreme and crash leaving government agencies no choice but to mandate a clean wing concept or no contamination on the critical surfaces. A good idea, but then there is the real world.
I expect it will work out for me next time as well.

White Hart

17th Oct 2006, 20:56

TURIN

17th Oct 2006, 21:13

With regard to de-icing - does a requirement to remote hold; taxy time over 20 minutes to departure point; last minute departure delay (late CTOT change/MDI/weather) etc etc have any bearing on your decision to depart after having de-iced on the gate? Do Company SOPs require you to cancel the departure and return to the gate to de-ice once again?

Seen it happen many, many times.

I still don't understand why pilots insist on putting their a/c and occupants at risk after all these years.

If it's got anything more than a light frost on the upper surface GET IT DE-ICED!
It's a helluvalot cheaper than the alternative smoking hole.

DC-Mainliner

17th Oct 2006, 23:31

If it's got anything more than a light frost on the upper surface GET IT DE-ICED!

The only time I've seen "polished ice" is in the case of very light frost wiped with a cloth until it was basically gone or smooth. Essentially, the new guidance prohibits this action, and light frost will require a de-ice. Deicing is the only sure fire way to go legally, and safely too.

Grunf

18th Oct 2006, 00:19

Turin

Agree, fully, with your statement!

I do not understand some pilots still being capable to take a brief look at the wing after the a/c has spent a night on a freezing tarmac (seen that in YUL, January, that day was -23C + 40 km/h wind?!?!?!).

He was one lucky bastard to fly away like that!:ooh:

Is it so hard and expensive to pay a visit to a de-icing facility for a shower plus TO TURN ON THE ANTI ICING TO MAX??

We all know it will burn a little bit more fuel (especially at take off) but it is still better then trying to test the new aerodynamic profile of the wing, right? :}

Cheers,

RatherBeFlying

19th Oct 2006, 22:55

After an interesting low level excursion in a ravine off the end of a runway while building airspeed (yes -- I had scraped all the frost between the rivet lines) I took to carrying a couple extra containers of windshield washer fluid along with a windshield sponge/squeegee.

No way would I dream of flying without a clean wing.

Exceptions can be made for frost over/under wing tanks where approved by manufacturer.

alexban

20th Oct 2006, 20:20

'currently still alowed'.....actually on Boeing aeroplanes it's NOT allowed to have any kind of deposits on wing surface,flight controls,leading edge....
Only thing allowed it's frost on the fuselage-light frost,you have to be able to see the markings,and ice on the underside of the wing ,due to cold fuel-this is also limited in length..but again the upperside of the wing must be clear.It is suggested that ,if any doubt,you should check by hand the evental presence of clear ice.

Roadrunner

7th Nov 2006, 23:21

I don't recall reading any reference to the possible affect of engine failure during TO when carry ice and snow on the wing and fuselage. A lot of people get away with TO carrying unacceptable amounts of contamination because they don't suffer an engine failure.

The slightest amount of contamination, eg. frost on a wing similar to a very fine grade sandpaper, results in up to a 30% reduction in lift and a 40% increase in drag. Add to that a failed engine and the bravest out there might start to sweat just a little.

So many companies, especially operators of freighters believe it is good enough to determine go or no go re the wing/fuselage at least, by looking from the top of the stairs. I have proved that to be woefully inadequate, by actually getting up and inspecting the wing up close.

I agree with comments re the total folly of accepting snow blowing off the a/c during TO. SAS have extensive material on the subject and they advise that you should never presume contamination will clear during TO.
Sound advice and worth heeding I believe.

The problem is that crew allow themselves to be pressure into not de-icing as it costs money and can delay the flight. Remember that companies write all sorts of stuff in their manuals to cover their back sides re cold weather operations and then often expect you to ignore it to keep the show on the road.
If you are caught breaking these rules for expediency, the company lawyers will burn you to save the company from litigation. You are only doing yourself a disservice by pushing the envelope.

Just my opinion.

Crossunder

8th Nov 2006, 10:09

The slightest amount of contamination, eg. frost on a wing similar to a very fine grade sandpaper, results in up to a 30% reduction in lift and a 40% increase in drag. Add to that a failed engine and the bravest out there might start to sweat just a little.
On which wing would that be? A DC-9 I presume? But what about the Pa-28, DHC-6, ATR or perhaps a sail plane? It all depends on the type of wing - especially wing loading and engine location. A thin layer of rime on my DHC8-100 is no problem - even with an engine failure. A DC-9, on the other hand, requires de-icing almost all year round.
And so I agree with punkalouver. You have to know your aircraft. We've all seen the NASA videos from the Twotter tests - but those were ridiculous amounts of ice, and I cannot believe that anyone would be foolish enough to attempt a take-off with that **** stuck to the wings/tail. I still think there's a huge difference between, say, the F28-4000 accident at La Guardia, where the wings were FULL of ice and snow (and they rotated too early), and a turbo prop with low wing loading and a little residual ice or frost.

ICEMAN757200

8th Nov 2006, 12:24

We do lots of winter OPS here in Iceland and our policy states No T/o with contaminated wings, we always do a very good pre-flt walk around and in winter pay even more attention to ENG intakes , Fan blades and ctrl surfaces.We' ll perform de- ice when required and respect HOT (hold over time)if HOT is over then we'll de-ice again .I think if you take off with a clean wing you' ll be always on the safe side. Of course we 'll use Eng AI on TO and if conditions are really bad:eek: (i.e. freezing rain)
we ' ll also use wing AI after TO.
Keep it Clean ,Keep it safe.:)

Roadrunner

10th Nov 2006, 01:33

Here, here.

To clarify, my previous post was referring to your average commercial jet.

Just doing some more reading via google search into the subject and they suggest that the tail plane will more readily ice up than the wing. Interesting that commercial jetliners don't have any tail anti-icing.
Do any aircraft have tail anti-icing or de-icing?

:ok:

Fellow Aviator

10th Nov 2006, 01:47

Here, here.
Interesting that commercial jetliners don't have any tail anti-icing.
Do any aircraft have tail anti-icing or de-icing?

:ok:

Doesn't bleed air or pneumatic boots count?

ICEMAN757200

10th Nov 2006, 03:16

Anti-icing/de-icing sys on modern jets are generally eng bleed air hot air systems.
In systems of this type the leading edge sections of wings including leading edge slats but not leading edge flaps,and tail units are usually provided with a second, inner skin positioned to form a small gap between it and the inside layer of the leading edge section.The hot air is ducted into the gap and provides sufficient heat(controlled by a shutter or butterfly VLV SYS) in the outer skin.The air is then exhausted through outlets in the skin surface or also ,in some cases, trough wing tips and tail units.The use of wing Anti Ice is not recomended on the ground ,cause it may damage the wing structure.
Electrical resistance heating sys or peneumatical operated de- icing boots are usually choosen for turboprops.

Grunf

10th Nov 2006, 15:29

...The use of wing Anti Ice is not recommended on the ground ,cause it may damage the wing structure...

Hello all.

ICEMAN,

You are right for the commercial jets but consider the possiblity of using the anti-icing on RJs or large turboprops at the airports without appropriate facilities (Canada is coming into mind, just from personal experience).

Also, some jets are designed to use the l/e anti-icing system on the ground. Good examples are Challengers (600 series, 300 series), Gulfstream as well as Bombardier's RJs (200, 700, 900).

They are all capable of using the stuff on the ground. During design of these models it was assumed that there will be no facilities for spraying available all the time.

The biggest problem was that too much bleed air would damage the l/e ribs plus too much heat just in front of you fuel tank would be a big no-no :=

I've seen ribs from test Challengers being black completely around the anti-icing going trough the leading edge :eek:

However one can assume the problem was more on the side of design i.e. improperly designed anti-icing system or better too much bleed air removed from the engine.

Amway, using bleed air on the ground is a considerable possiblity, especially on remote airfields.

Cheers

Ice-bore

10th Nov 2006, 18:56

I believe that after the Washington crash in 1982 Boeing modified the wing TAI system on 737 aircraft, to allow it to be used on the ground. However, while the L/E may be the most critical part of the wing, the entire upper surface must be free of frozen contamination at takeoff.

In the unlikely event that the only part of the aircraft with frost or ice on it was the L/E, selecting wing anti-ice would certainly remove it but the potential then exists for melting frost or ice to run back and re-freeze behind the L/E. To imply that this system can be used on the ground, in lieu of a standard de-/anti-icing operation, is in my opinion highly dangerous.

There would also an issue with selecting wing anti-ice on the ground, immediately following de-icing or anti-icing with Type II or IV fluid. The fluid remaining on the heated L/E would evaporate fairly quickly, leaving behind deposits of dried out thickening agent. Add moisture at some stage in the future and the water soluble thickener will swell to form a gel like substance on the L/E.

ICEMAN757200

10th Nov 2006, 22:49

Grunft your are probably right on using anti-Ice on the ground :D it varies between acft , on the 757 it is automatically inihibited on the ground.Good to know we always learning something new.:ok:

ICEMAN757200

10th Nov 2006, 22:51

Very interesting post Ice-Bore I had forgot that aspest of using wing AI on ground:ok: cool!!

Grunf

11th Nov 2006, 17:12

Well, my job was more on the structural side (issues with too much bleed air going through the tube).

I have no procedural knowledge of what way they were using it but I am quite sure they have tested it in Iqaluit (north of Canada, province of Nunavut).

You have to check with someone flying these smaller jets a little bit "up north" to see what's their procedure.

Cheers

howflytrg

11th Nov 2006, 21:47

I find it interesting to read recently that the CAA have issued a warning with regards to the use of Type II/III/IV fluids and the number of applications. The residues left over from the fluids can dry out and when re-hydrated swell up to form a thick paste. After a number of aplications the amounts of residue can cause flight control problems! Yet more things to think about on these cold mornings!

Still though, if in doubt DEICE the thing!

By the way, with regards to the use of AI. 737's are not permitted to use wing AI whilst on the ground or on the TO roll.

Ice-bore

12th Nov 2006, 11:49

By the way, with regards to the use of AI. 737's are not permitted to use wing AI whilst on the ground or on the TO roll.
Not sure if applicable to all models but was under the impression that the 737 wing TAI system can be used on the ground. Should an overheat condition exist the wing anti-ice ground thermal switch will trip, when the bleed air temp reaches 125 degrees C, to protect the structure.
Would agree that it can't be used during takeoff as the wing TAI switches will automatically move to the OFF position. This reduces engine bleed loads and conserves thrust for climb.
Are you suggesting that Boeing do not permit use of this system on the ground or that your company do not allow it ?

FullWings

12th Nov 2006, 13:37

Of course we 'll use Eng AI on TO and if conditions are really bad (i.e. freezing rain)
I understand the sentiment but is any aircraft certified to operate in freezing rain == severe icing? I always thought this was a complete no-no...

alexban

12th Nov 2006, 20:01

From SP.16 ,737 FCOM :
Use wing AI ,during all ground operations between engine start and take off when icing conditions exist or are anticipated,unless the airplane is,or will be protected by use of type 2 or type 4 fluid in complance with an approved ground de-iceing program.
Warning: do not use wing anti-ice as an alternative for ground de-iceing/anti-icing.Close inspection is still needed to insure that no frost,snow or ice is adhering to the wing,LE devices,stabilizer,control surfaces or any other critical aircraft components at take-off.
I very much doubt that any company will,for some reason decide not to follow this.
One big problem with taking off with 'some' ice on the wings is the chance of not symetrical icing of both wings,and you'll be amased how fast you'll do a barrel roll,even with a heavier airplane.It's just aerodinamics.
And ,unfortunately ,it happened already,so you better learn from their death.

The Bartender

14th Nov 2006, 15:53

A thin layer of rime on my DHC8-100 is no problem - even with an engine failure.

"Wings, tail and control surfaces shall be free of ice, snow. slush, and frost, except that a coating of frost may be present on wing lower surfaces in areas coldsoaked by fuel between forward and aft spars, in accordance with the aircraft manufacturer's published manuals."

You should know that (rather long) sentence... It's your aircraft it's refering to...:ouch:

Grunf

16th Nov 2006, 15:08

hell all.

Talking 'bout the Devil: here is an excerpt from the latest Most Wanted List from NTSB on icing (http://ntsb.gov/Pressrel/2006/061114.htm):

November 14, 2006 SB-06-61

"...Aircraft Icing -- The consequences of operating an airplane in icing conditions without first having thoroughly demonstrated adequate handling/controllability in those conditions are sufficiently severe that they warrant a thorough certification test program.

The FAA has not adopted a systematic and proactive approach to the certification and operational issues of airplane icing. Recommendation: Complete research on aircraft structural icing and continue efforts to revise icing certification criteria, testing requirements, and restrictions on operations in icing conditions.

Evaluate all aircraft certified for flight in icing conditions using the new criteria and standards. Timeliness Classification: Unacceptable:D ...."

So, watch out, please.

Cheers