Tail icing
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There is a way, I've stood out on the wing several times this season already, thanks to Boeing for the fantastic emergency exits on the NG (still shocks the cabin crew though, closing them seems to be difficult for most 
). We've got the same paragraph in our manuals about the upper wing frost with the addition that 'this procedure is suspended until approval from the authorities'... The same problem comes up often though, airports without deicing facilities and a minute but still visible layer of frost on top - no good solution here unfortunately I suppose.
). We've got the same paragraph in our manuals about the upper wing frost with the addition that 'this procedure is suspended until approval from the authorities'... The same problem comes up often though, airports without deicing facilities and a minute but still visible layer of frost on top - no good solution here unfortunately I suppose.
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Watch and be aware of the effects of tail icing...
YouTube - NASA Tailplane Icing Video Glenn Research Center
ECAM Actions.
YouTube - NASA Tailplane Icing Video Glenn Research Center
ECAM Actions.
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A Twin Otter is not a jet.
Had a Boeing factory tour by a BCA test pilot. Asked him about tail de-icing. Like others have said - you don't need it. Flight test showed it had no effect and when it got large enough it came off.
That is not to say it's OK to take-off with ice. It is not. The flight test is about inflight. On the ground it is not acceptable to have ice on the tail prior to departure.
Had a Boeing factory tour by a BCA test pilot. Asked him about tail de-icing. Like others have said - you don't need it. Flight test showed it had no effect and when it got large enough it came off.
That is not to say it's OK to take-off with ice. It is not. The flight test is about inflight. On the ground it is not acceptable to have ice on the tail prior to departure.
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So what question are we asking?
Is it fiscally okay to mitigate our assessment of contamination on certain aerodynamic surfaces?
I can understand the frustrations here; there has been insufficient research carried out on the middle ground.
We know what happens at the extremes.
Contamination = danger
Clean= safe
But aircraft operate in conditions where ice accumulates over time.
Obviously the aircraft can tolerate some level of contamination.
But where is the cut off point?
I don't think there is an aviation authority out there that would be brave enough to make a call like that.
And I don't think it is for us to take up the baton in the interim.
So as frustrating as it might seem I think unless the aviation industry is prepared to put a vast amount of investment on the specifics of partial icing then we have to accept the regulations incomplete as they are for what they are.
Is it fiscally okay to mitigate our assessment of contamination on certain aerodynamic surfaces?
I can understand the frustrations here; there has been insufficient research carried out on the middle ground.
We know what happens at the extremes.
Contamination = danger
Clean= safe
But aircraft operate in conditions where ice accumulates over time.
Obviously the aircraft can tolerate some level of contamination.
But where is the cut off point?
I don't think there is an aviation authority out there that would be brave enough to make a call like that.
And I don't think it is for us to take up the baton in the interim.
So as frustrating as it might seem I think unless the aviation industry is prepared to put a vast amount of investment on the specifics of partial icing then we have to accept the regulations incomplete as they are for what they are.
Last edited by safewing; 3rd Jan 2013 at 08:37.
Ok, it not a jet but:
ASN Aircraft accident Vickers 838 Viscount SE-FOZ Stockholm-Bromma Airport (BMA)
and:
http://www.aaib.gov.uk/cms_resources...8%20G-BMAU.pdf
Icing is not to be messed with, it has killed lot of people.
ASN Aircraft accident Vickers 838 Viscount SE-FOZ Stockholm-Bromma Airport (BMA)
and:
http://www.aaib.gov.uk/cms_resources...8%20G-BMAU.pdf
Icing is not to be messed with, it has killed lot of people.
Boeing OKed it and our local EU-authority is happy with that.
Nothing new, either.
Now, lets look at wing anti-icing on large (heavy) swept wing jet aircraft.
I flew the 707 in command for seven years, and did not once use wing anti-ice
No problems noted.
Now, after flying the L1011 for thirty years, used wing anti-ice perhaps half a dozen times...and only then because the airplane is equipped with an airframe ice detector, and the new First Officer bacame agitated and thought we would fall out of the sky, otherwise...gotta keep the co-pilot happy.
The aircraft of which you speak are very old and very inefficient. Modern airliners are much more sensitive to icing than before. The reason being is that we operate them much closer to the limits than ever before. By doing this we extract more efficiencies from the airframe, use less fuel, and carry more weight.
Any icing on a modern aerofoil is a big deal, especially icing on the leading edge. The Challenger accident in Birmingham should have left us all in no doubt about that.
http://www.aaib.gov.uk/cms_resources...04%20N90AG.pdf
I will draw your attention to points 18 and 19 in the Causes section of the accident report.
18. A small degree of wing surface roughness can cause a major reduction in the wing stall angle of attack.
19. Wing surface roughness associated with frost contamination caused sufficient flow disturbance to result in a wing stall at an abnormally low angle of attack. The stall protection system was ineffective in this situation.
19. Wing surface roughness associated with frost contamination caused sufficient flow disturbance to result in a wing stall at an abnormally low angle of attack. The stall protection system was ineffective in this situation.
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The Challenger is like the old DC-9 short body A/C with and the F-28. Jets with no leading edge devices and therefore, extremely sensitive to icing contamination.
Bottom line......less margin to a stall. Never consider taking off with wing contamination on the above aircraft. Of course many will say that you never should with any aircraft and of course those are the rules, but it does help to be knowledgeable on which A/C are more vulnerable and why.
Bottom line......less margin to a stall. Never consider taking off with wing contamination on the above aircraft. Of course many will say that you never should with any aircraft and of course those are the rules, but it does help to be knowledgeable on which A/C are more vulnerable and why.
Last edited by JammedStab; 3rd Jan 2013 at 16:45.
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Totally agree with the first paragraph above. This is the conclusion of the UK CAA to a Challenger accident a few years back at EGBB (Birmingham,UK)..........
Immediately after takeoff from Runway 15 at Birmingham International Airport the aircraft began a rapid left roll, which continued despite the prompt application of full opposite aileron and rudder. The left winglet contacted the runway shoulder, the outboard part of the left wing detached and the aircraft struck the ground inverted, structurally separating the forward fuselage. Fuel released from ruptured tanks ignited and the wreckage slid to a halt on fire; the Airport Fire Service was in attendance less than 1 minute later. The accident was not survivable.
Numerous possible causes for the uncontrolled roll were identified but all except one were eliminated. It was concluded that the roll had resulted from the left wing stalling at an abnormally low angle of attack due to flow disturbance resulting from frost contamination of the wing. A relatively small degree of wing surface roughness had a major adverse effect on the wing stall characteristics and the stall protection system was ineffective in this situation. Possible asymmetric de-icing by the Auxiliary Power Unit (APU) exhaust gas during pre-flight preparations may have worsened the wing-drop tendency.
Immediately after takeoff from Runway 15 at Birmingham International Airport the aircraft began a rapid left roll, which continued despite the prompt application of full opposite aileron and rudder. The left winglet contacted the runway shoulder, the outboard part of the left wing detached and the aircraft struck the ground inverted, structurally separating the forward fuselage. Fuel released from ruptured tanks ignited and the wreckage slid to a halt on fire; the Airport Fire Service was in attendance less than 1 minute later. The accident was not survivable.
Numerous possible causes for the uncontrolled roll were identified but all except one were eliminated. It was concluded that the roll had resulted from the left wing stalling at an abnormally low angle of attack due to flow disturbance resulting from frost contamination of the wing. A relatively small degree of wing surface roughness had a major adverse effect on the wing stall characteristics and the stall protection system was ineffective in this situation. Possible asymmetric de-icing by the Auxiliary Power Unit (APU) exhaust gas during pre-flight preparations may have worsened the wing-drop tendency.
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Within the next 2 years it is likely that Europe will regulate deicing.
Some basic questions still come to the fore.
How do we minimise the human error?
How do we regulate compliance?
How do we monitor in real time the weather so that we can provide holdover confidence.
In North America many steps are being taken to address these questions. How long will it be until these are implemented in Europe after it introduces the regulation.
It won't be overnight.
Some basic questions still come to the fore.
How do we minimise the human error?
How do we regulate compliance?
How do we monitor in real time the weather so that we can provide holdover confidence.
In North America many steps are being taken to address these questions. How long will it be until these are implemented in Europe after it introduces the regulation.
It won't be overnight.
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@safewing & Jonti
@safewing & Jonti
I hope you are aware that you are posting in a thread that has been slumbering for almost two years. Nothing wrong with that, just thought I should mention that, since you might not receive answers to posts you quote as people might have forgotten that they posted in this thread.
That is especially valid for the post Jonti quoted made originally by 411A regarding the 1011. 411A is no longer amongst us and won't be able to reply.
Cheers,
DBate
I hope you are aware that you are posting in a thread that has been slumbering for almost two years. Nothing wrong with that, just thought I should mention that, since you might not receive answers to posts you quote as people might have forgotten that they posted in this thread
.That is especially valid for the post Jonti quoted made originally by 411A regarding the 1011. 411A is no longer amongst us and won't be able to reply.
Cheers,
DBate
Last edited by DBate; 3rd Jan 2013 at 21:04. Reason: typos
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Dbate
I would imagine the topic transcends time, but I acknowledge what you're saying.
Dufo
Yes it will be expensive but so is carbon/emission trading.....and we all know how well that's going.
That said EASA need to step up to the plate and bring Europe up to the same standards as the US and Canada. For too long we've been hanging onto their shirt tails on this subject
Not wishing to minimise anyone in Europe but we are playing catch up.
I would imagine the topic transcends time, but I acknowledge what you're saying.
Dufo
Yes it will be expensive but so is carbon/emission trading.....and we all know how well that's going.
That said EASA need to step up to the plate and bring Europe up to the same standards as the US and Canada. For too long we've been hanging onto their shirt tails on this subject
Not wishing to minimise anyone in Europe but we are playing catch up.
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Some basic questions still come to the fore.
How do we minimise the
human error?
How do we regulate compliance?
How do we monitor in
real time the weather so that we can provide holdover confidence.
More expensive for the operators and manufacturers than pushing it to the regulator for a cheap licensing/approval fix. Current practise remains fundamentally a PROCESS driven safety activity and is inherently prone to error.
There is data in abundance regarding loss of control where aircraft departed with an unsafe level of contamination. There is little, if any, data regarding normal departures with an unsafe level of contamination.
Therefore I am not surprised by the "it never happened to me" inputs on this thread.
Personally,
- It's always clean wing concept for me(especially as I am not actually connected to my modern, computer controlled one).
- I don't trust the fluids(fluid standards are controlled largely by the fluid manufacturers. Nice.)
- Surface roughness and location is the key, not (just) the AMOUNT.
If it is safety returns we are after, better to start with regulating the unlicensed, un-approved 'design' companies that fill our black boxes with software such as is needed to detect an icing induced stall(bombardier challenger SPS system, in the accident at BHX referred to above)!!
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Darkbarly
I hear what you're saying but where would you place the temperature sensors?
There are studies being carried out to look at monitoring skin temperature with IR thermometers, but it is early days.
My concerns are symmetrical application using one vehicle, while it is possible as per the guidelines my concerns would be;
fluid quality on the side that is sprayed first and that which is sprayed last, ie maximum disparity on main lifting surfaces =maximum possibility of assymmetry.
representative surfaces for pilots to view; better to spray wings first tail last.
time taken to complete the process i.e. application eroding holdover.
sectional de-icing and anti-icing with one vehicle in active conditions.
understanding the snowfencing phenomena (a big gotcha)
and as you've said aircraft skin temperatures versus ambient temperature.
I hear what you're saying but where would you place the temperature sensors?
There are studies being carried out to look at monitoring skin temperature with IR thermometers, but it is early days.
My concerns are symmetrical application using one vehicle, while it is possible as per the guidelines my concerns would be;
fluid quality on the side that is sprayed first and that which is sprayed last, ie maximum disparity on main lifting surfaces =maximum possibility of assymmetry.
representative surfaces for pilots to view; better to spray wings first tail last.
time taken to complete the process i.e. application eroding holdover.
sectional de-icing and anti-icing with one vehicle in active conditions.
understanding the snowfencing phenomena (a big gotcha)
and as you've said aircraft skin temperatures versus ambient temperature.
Last edited by safewing; 5th Jan 2013 at 15:24.
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If anyone wants a powerpoint presentation on the Airfoil Performance Monitor (the only device to provide real-time info on the margin remaining to the stall on clean or contaminated airfoils - both main wing and horizontal stab - as well as during takeoff run) please pm me.
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First off, anyone with experience in serious ice, not common, with the experience of flying small to large planes...not common pretty much laughed when NASA came out with their icing research.
Jet pilots flying back and forth over the Cascades, my stomping grounds, talking about how 'bridging' is a fallacy, that newer boots deal with that, on and on. It was a complete joke.
Simply put, 99% of the planes out there don't have the newer designed boots, nor do we fly jets that zip us through the upslope ice with 1 minute of exposure whilst accelerating through 250 kts.
So forget the jet guys, or the NASA guys, or the airline guys and what they think about ice when all they have to do is hit the boot and push the throttles forward to deal with icing.
IN the rest of the world, you have to live at 14,000 feet with boots that don't work that well, pushed by little vacuum pumps. You can't climb out, accelerate, or just turn around and spend another hour going back through the place you accumulated the ice to begin with.
That said, in a forum full of guys that purport to know what they are talking about, I can assure you that tail plane icing is so stupid real, when you have an aft CG on climb out with up slope icing on all over, the difference in the climb was 500ft/m vs 0 Ft min with mountains looming, by simply getting passengers to move to a more centered location. So yeah, tail plane icing is THAT real.
Jet pilots flying back and forth over the Cascades, my stomping grounds, talking about how 'bridging' is a fallacy, that newer boots deal with that, on and on. It was a complete joke.
Simply put, 99% of the planes out there don't have the newer designed boots, nor do we fly jets that zip us through the upslope ice with 1 minute of exposure whilst accelerating through 250 kts.
So forget the jet guys, or the NASA guys, or the airline guys and what they think about ice when all they have to do is hit the boot and push the throttles forward to deal with icing.
IN the rest of the world, you have to live at 14,000 feet with boots that don't work that well, pushed by little vacuum pumps. You can't climb out, accelerate, or just turn around and spend another hour going back through the place you accumulated the ice to begin with.
That said, in a forum full of guys that purport to know what they are talking about, I can assure you that tail plane icing is so stupid real, when you have an aft CG on climb out with up slope icing on all over, the difference in the climb was 500ft/m vs 0 Ft min with mountains looming, by simply getting passengers to move to a more centered location. So yeah, tail plane icing is THAT real.
A strange post Jonty.
The points worth raising about the OP you quoted are really that, one should give icing the fullest respect and follow the latest guidance on icing/de-icing proceedures.
OAP
The points worth raising about the OP you quoted are really that, one should give icing the fullest respect and follow the latest guidance on icing/de-icing proceedures.
OAP
Immediately after takeoff from Runway 15 at Birmingham International Airport the aircraft began a rapid left roll, which continued despite the prompt application of full opposite aileron and rudder. The left winglet contacted the runway shoulder, the outboard part of the left wing detached and the aircraft struck the ground inverted, structurally separating the forward fuselage. Fuel released from ruptured tanks ignited and the wreckage slid to a halt on fire; the Airport Fire Service was in attendance less than 1 minute later. The accident was not survivable.
Numerous possible causes for the uncontrolled roll were identified but all except one were eliminated. It was concluded that the roll had resulted from the left wing stalling at an abnormally low angle of attack due to flow disturbance resulting from frost contamination of the wing. A relatively small degree of wing surface roughness had a major adverse effect on the wing stall characteristics and the stall protection system was ineffective in this situation. Possible asymmetric de-icing by the Auxiliary Power Unit (APU) exhaust gas during pre-flight preparations may have worsened the wing-drop tendency.
Numerous possible causes for the uncontrolled roll were identified but all except one were eliminated. It was concluded that the roll had resulted from the left wing stalling at an abnormally low angle of attack due to flow disturbance resulting from frost contamination of the wing. A relatively small degree of wing surface roughness had a major adverse effect on the wing stall characteristics and the stall protection system was ineffective in this situation. Possible asymmetric de-icing by the Auxiliary Power Unit (APU) exhaust gas during pre-flight preparations may have worsened the wing-drop tendency.
off topic somewhat but... approximately 2 years before this event, a similar incident occurred on an CRJ200 out of LJU, but was not disseminated in a helpful manner that would have highlighted the susceptibility of the type to low levels of contamination. Types with no leading edge devices are particularly sensitive to contamination.
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Tail icing
DC-ATE: Why would you add 10-15 kts to your approach speed in a 737 if WAI was used? As far as I know that's NOT recommended for 2 eng ops ( only SE Vref Ice). Your stall warning logic for the entire flight will already have changed just by selecting it ON once. Your "home made" safety advice might end with a bad landing in the best case. A long landing on an icy runway in the worst case. My point: stick to Boeing procedures and you will be safe - or at least safer!!
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Certification / Unheated and no TAI on stabs
Hi,
Late answer I'll try to make it short.
Certification require aircraft manufacturers to demonstrate that any stablizer icing will not impact the ability to manoeuver the aircraft.
Every aircraft type is now tested and sometimes modified to comply with this requirement.
Late answer I'll try to make it short.
Certification require aircraft manufacturers to demonstrate that any stablizer icing will not impact the ability to manoeuver the aircraft.
Every aircraft type is now tested and sometimes modified to comply with this requirement.