ICE crystals

[BOAC]

Rainboe - you are confused by the meteorology you learnt all those decades ago. It is true that at temperatures below -40, the amount of water vapour that can be held in air is so small as to render super-cooled droplets irrelevant, and that is the basis for the existing guidance. HOWEVER, in conditions of strong convective or lenticular activity, sc droplets can be carried aloft into temperatures well below -40. Ice crystals are also a threat to engines at those temperatures as you should have read on these very forums. Things HAVE changed. You will do what you are used to over '40 years', of course. Others take note of new information and learn. Out of interest, what do you see as the problem in using anti-ice in relevant high-level cloud at temperatures below -40, apart from a very small fuel penalty and the fact that you will no doubt have noticed over the years that the 'bible' does not say you should not use it?

[falconer1]

well, Rainboe...

would humbly suggest, you try to "get some updates" for your 40 year old SOPs..

to call a Boeing AERO article "dodgy accident connections and theoretical papers"..well, how about you contact Boeing and try to set them straight???

strange perceptions you have..

[shortfuel]

Originally Posted by Rainboe

What you have done is to thoroughly confuse a learner after an uncomplicated answer.

Really...? The question (and this topic in general) is actually far more complicated for anyone on this forum.
But that was a good opportunity to review/discover/share thoughts on that phenomenon and its operational impact.

As for the OP, try not to speak on his behalf, that would be a good start.

[MexCrew]

to Rainboe

Though your comment wasn't necessarily directed at me, I didn't make reference to a theoretical paper on my previous post but rather a direct quote from the 'Boeing Flight Crew Operations' manual and said 'Bulletin' is still (IE) 'In Effect' so as far as conventional wisdom suggests perhaps a buzz to Tech Pilot or Tech Dept of one's largest airline to ask for Boeing's latest bulletin updates is in order.

Furthermore, I don't think that ice crystals have the ability to distinguish between aircraft or engine types.

Blue skies,

MC

[john_tullamarine]

I'm sure that Rainboe has big enough shoulders to withstand a little critical comment. However, I would ask that we keep criticism to objective comment and not allow it to move into subjective pejorative .. ie "play the ball .. not the player"

[Jimmy Do Little]

For those flying on the bus, FCTM says to turn Engine Anti Ice ON when flying near CBs even if TAT is <-40°c ! that's mainly because of ice particle icing (e.g. in an anvil).

Is there are more current version of the FCTM, or was that a Typo?

FCTM 04.010... (A320) July 2008 Version
FCTM 5.10.5... (A330, A340) 2006 Version

"...CLIMB/ DESCENT
Whenever icing conditions are encountered or expected, the engine anti-ice should be turned on. Although the TAT before entering clouds may not require engine anti-ice, flight crews should be aware that the TAT often decreases significantly, when entering clouds.

In climb or cruise, when the SAT decreases to lower than -40 °C, engine anti-ice should be turned off, unless flying near CBs..."

Also.....

FCOM 3.4.30 (Rev 39)

"...icing conditions may be expected when the OAT (on ground and for take-off), or when the TAT (in flight) is at or below 10 c, and there is visible moisture in the air (such as clouds, fog with low visibility of one mile or less, rain, snow, sleet, ice crystals) or standing water..."

Could we say the same for flying trough ICE crystals?

Someone had mentioned earlier that the query related to Boeing, thus the "Boeing Bulletin" would apply. But, it's interesting to note that Airbus seems to agree (...Ice Crystals...).

Like some other examples between the two, Airbus says "do this, don't do that," Boeing tells you why.

[Rainboe]

Let's try again,

to call a Boeing AERO article "dodgy accident connections and theoretical papers"..well, how about you contact Boeing and try to set them straight???

strange perceptions you have..

Some of you are quoting Airbus procedures and some are quoting from theoretical papers, not official documents. All I see are up-to-date procedures from my OMB Procedures.

I have spent much of a 38 year career flogging up and down over the depths of Africa at night through Cbs, and across the ITCZ in the Indian Ocean. Once below -40C, anti-icing never went on. Even in severe turbulence and precipitation, forget 'near Cbs, this is in them. Until I see my manuals changed to reflect advice, I don't see that a problem has been proved that aeroplanes cannot handle it. Strange and weird some of you chose to respond to this with personal insults! I've spent a career there. I see no problem with current standard procedures and advice. I'm afraid I am too busy working to go reading theoretical papers and unsubstantiated and unproven theoretical possible accident causes. The advice has not let down me or BA in at least 40 years that I know of.

When the manuals change, I will be happy to amend my procedures, but I am not taking anonymous advice from posters who seem hung up on theoretical papers or private accident theories, or trying to use home-grown procedures pending what might be future procedure changes. I have yet to see anything 'official' despite the over-reaction of some of you who don't appear to understand what working to a manual and 'established' procedures means.

I don't intend discussing this further. I have given the official Boeing line. One wishes one hadn't bothered answering in the first place. The chap just need an answer to a simple query- instead of 'yes' or 'no', he gets 2 pages of unproven theories and Airbus procedures!

[PantLoad]

Touchy Subject...

Gentlemen,

Obviously, this has become a sensitive topic....for whatever reason.
So, I will emphasize that we all need to follow our company's SOPs,
regardless of what manufacturers say, regardless of PPrune says.
I'm sure I don't need to explain why the SOP is most important.

I'll say no more, except to answer the question of which issue of the
Airbus FCTM I reference.

It's: A-320 Airbus Flight Crew Training Manual, "Supplementary Information" Section SI-010 P4/16 Issue date: 24 JUN 09.
(This is the latest page issue from Airbus.)


Fly safe,

PantLoad

[Jimmy Do Little]

I'll say no more, except to answer the question of which issue of the Airbus FCTM I reference.

Sorry, was refering to the quote by "Shortfuel" (post #7)

[shortfuel]

Jimmy,
Definitely a typo (I meant SAT).



Rainboe,

Telling people that ice does not form anywhere on the engine below -40°C is a falsehood due to your ignorance on this topic (?).
Happy flying in African CBs! But interesting attitude of yours "I did it many times, nothing happened to me".
BTW, there was no personal insult on this thread.

[Jimmy Do Little]

Obviously, this has become a sensitive topic....for whatever reason.

What's odd about this, is that a group of people who are supposed to be trained in CRM, etc, have such a difficult time accepting someone elses point of view when it contradicts their own.

I recall, albeit, from a long time ago "...agree to disagree...but respect each others opinions" What ever happened to that?

-------------------------------

definitely a typo

Figured as much. Cheers

[Rainboe]

Telling people that ice does not form anywhere on the engine below -40°C is a falsehood due to your ignorance on this topic (?).
Happy flying in African CBs! But interesting attitude of yours "I did it many times, nothing happened to me".

One last time! I have never seen ice below -40C in over 20,000 hours flying, and do not accept it actually forms. Neither does both my airlines, which publish manuals telling me such and a procedure to follow which has been followed and never known to be substandard. My 'ignorance' or your dunderheaded refusal to accept current procedures?

If Airbus has a problem with pitot tubes, I would like to see proof and new procedures. But I know nothing about Airbuses, or any wish to learn!

[shortfuel]

If you can't sustain a contradictory debate, don't bother replying.

I just assumed you were ignorant on that topic (hence the "?"). Nobody called you ignorant.

As far as I know, BA does not edict the laws of physics, do they?

I dont' really care about your company procedures and I never intented to convince you. The OP asked about a MET/physics related phenomenon and you peremptorily answered with your outdated (my opinion) company procedure based on a false statement.

Icing (not supercooled water icing with Liquid Water Content but ice particle icing) can form below -40°c in particular conditions wether you like it or not and crystal icing is a potential threat for aviation ops (and that statement is not from me, it's from Boeing / GE / NASA / FSF...).

[Airbus had many problems with certain pitot tubes, as for the proof, you have google or EASA AD section ]

[Jimmy Do Little]

Rainboe. I agree with you! But, if I had said it, it would have gone like this....

I have never seen ice FORM below -40C in over 20,000 hours flying. Below -40C, I've only ever flown in Clear skys, or Ice!

Ice can form below -40°c in particular conditions wether you like it or not

Sorry, I don't agree.

Then, along comes someone (Boeing) and says that we can take that ice (or water vapour) and heat it up; thus melting it within the engine(Simple summary). Okay, turn the Anti-ice on.

Is it that complicated?

Bottom line. Employer pays me $XXXXX per month to fly their airplane, their way. If they want engine anti-ice on below -40c, and they publish that requirment in an approved document (FCOM, SOP, etc), I'll do it. Just keep the paycheck coming.

[Genghis the Engineer]

Oddments:


- It's known that in the last decade or so, there have been 100ish incidents of engine rollback in conditions which are consistent with high IWC (iced water content).

- High IWC is different to icing conditions.

- Experience says that high IWC is not readily visible from a cockpit, and that the instrumentation to detect it is only fitted to a handful of specialist research aeroplanes around the world.

- NASA is currently pursuing a research programme into this. It's in several parts but will include flying one or more research aeroplanes to look into what conditions exist where. An out of date news article here suggests use of a modified S3 Viking, although I have a little inside knowledge which suggests that it'll now be something else - as yet undecided.

- NASA is working with FAA and the Australian Bureau of Meteorology of the programme. This is because they want to look at flying in the vicinity of Darwin where they've got a good combination of ground facilities and weather.

- The concern is about core and compressor stator icing due to partial melting then congealing of iced water crystals. The mechanism isn't well understood but it's believed that where it occurs it takes some time (15 minutes has been quoted to me) to start to get an appreciable power loss. So, you'd have to stay in those conditions for some time.

- They aren't worried about airframe or intake icing - those are well understood, and all airliners have adequate information about their avoidance and treatment. This is something quite new.

G

[MU3001A]

Rainboe: One last time! I have never seen ice below -40C in over 20,000 hours flying, and do not accept it actually forms.

I have never seen ice form inside an engine, period and am unlikely to ever do so. Doesn't mean I'm going to wait until I personally experience a rollback or flame out in conditions where ice should not form, or discount the ice crystal phenomenon or ignore manufacturers recommendations to counter the risk.

[BOAC]

Alejandro - now that Rainboe has (finally?) left this thread, may I summarise?

You asked in #1 about a phenomonen (ice crystal icing) about which some posters know nothing because it is not in their 'drivers' handbook' Others do, including major engine and aircraft manufacturers. Good on you for asking. Please take note that it is thought to be a significant occurrence. Manuals will eventually be amended if it is thought necessary. There is information published by various manufacturers which obviously has not reached the third level airlines yet.

It is up to you how you progress this. Keep an open mind and keep asking questions and looking for information.

As a final thought, it is only in the last 20 years or so that the legal requirement for London Taxis ('Hackney carriages') to carry a bale of hay in the back for the horse has been dropped. Progress indeed. It is true that not a single horse ran out of hay in a motorised London taxi in the years the law was in place.

[punkalouver]

A look back at the first post shows that the original question appears to be in general and not about a specific type. Despite claims that it is only from a Boeing point of view, that original poster may go onto other aircraft. Other people reading this thread may be on different types and when they read from a supposedly experienced type that ice is NOT going to happen below -40, they may believe it.

Examples are given showing that engines have been flaming out and aircraft involved in serious incidents much more than previously thought, yet the accusation is made that they are from "dodgy accident connections and theoretical papers" even though a Boeing magazine is quoted.

Then it is said that in 38 years of flying, icing below -40 has never been experienced even though this thread is about unseen icing in engines from ice crystals that don't accumulate on the airframe. 99% of us or more have likely never seen such icing either.

I am going to post a link to perhaps another dodgy accident connection. That is the NTSB. It talks about several of these incidents. One of them, a Beechjet was at FL 380 with a static OAT of -57°C as read in the actual accident report.

http://www.ntsb.gov/recs/letters/2006/A06_56_59.pdf

I think the original poster and others have more than one thing to learn about on this thread. One from a technical point of view and another from a human factors point of view on aviation hazards. And remember, what happens on one aircraft can be much different to what the same effect does to another aircraft. Also remember remember that over the course of your career you will receive much false/misleading information from others that you talk to.

Here are some quotes.

"The Safety Board is well aware of the threat that ice crystals can pose to turbine engines. On June 4, 2002, Spirit Airlines flight 970, a Boeing MD-82 airplane,15 experienced a dual-engine flameout of its Pratt & Whitney JT8D-219 engines after high altitude ice crystals blocked the engines’ inlet pressure probes while the airplane was in cruise flight at FL 330."

"During the investigation of the dual-engine flameout events, it was learned that a general perception exists among flight crews of airplanes that fly at high altitudes that ice is not a threat at the higher altitudes because it is “too cold.” This perception is reinforced by the fact that the ice crystals that are of concern do not accrete on the usual places that pilots look for ice such as the wings, windshield wiper blade arms, or the arm retaining bolts."

"The Safety Board notes that the problem of multi-engine losses of power due to icing is not limited to the JT15D-5 engine and that General Electric CF6-80 series engines have also experienced in-flight losses of power due to internal icing.

[Basil]

I'm pretty certain that Rainboe, like most experienced jet pilots is aware that, when flying in the proximity of convective systems, anvils and the like, all bets re icing are off and whilst I may not (manually for some types) switch on the engine anti-icing I'd be keeping an eye on the parameters.
A lot of the published material is engine specific, e.g. FAA document which refers to <<B767 & B747 aircraft fitted with GE CF6-80C2 and CF6-80A engines >> I note punkalouver's post also refers to P&W.

p.s. Rainboe, that's a pint you owe me

[punkalouver]

Originally Posted by Basil

A lot of the published material is engine specific, e.g. FAA document which refers to <<B767 & B747 aircraft fitted with GE CF6-80C2 and CF6-80A engines >> I note punkalouver's post also refers to P&W.

p.s. Rainboe, that's a pint you owe me

The NTSB report does make this reference on page 8 of their report:

"The Safety Board is aware of a June 1, 2006, dual-engine flameout that occurred on a Qatar Airways A-330 airplane equipped with General Electric CF6-80E1 engines while the airplane was descending through IMC for landing at Shanghai, Peoples Republic of China."