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the reason to de-ice
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and Commercial Pressures...
and also of interest...
"It [AAIB report] also revealed the pilot had been recovering from a bad cold but felt pressure to fly being the only pilot in Aberdeen qualified to fly to the Faroe airport. " and Eastern's response... "As a company, our policies regarding 'fitness to fly' have always clearly stated that crew members should not operate if they do not feel fit to do so." This will always be the response from any airline if a pilot reports (provided they are still alive) on any investigation (internal, ASR or AAIB) that they felt under commercial pressure to operate... |
As you say, they'll always counter with that argument. Perhaps one way to head that off, for those unfortunate enough to be assisting an investigation, would be to refer to the monitoring procedures that the companies presumably have (my non-airline employer does anyway) for counting sick days and having 'offer to help' (meaning 'we're watching you') meetings for those who have more sick days than average.
I'm not sure that was the story in this case though - the way I read the story was that he was being a good guy and wanting to get the pax to their destination. It's not like there'll be another one along in a minute from Aberdeen to the Faroes. |
In the last 20 years I've worked both permanent/ long term and short term contracts for many companies.. almost never have had to call in sick but with the exception of one company (US non-profit) have in every case been given a hard time and made to feel that I'm letting the company/fellow crew and pax down...
In the current market there's even less slack in the system to allow for short notice changes in the rosters. |
Very lucky they were
It would appear from reading the AAIB report that not only was the Captain not fit to fly but neither was the aeroplane with an elevator coated with slush.
Since the elevator trim gave reversal - does anyone who knows the Jetstream 41 - know if it is a tab that acts aerodynamically on the elevator - that would explain that methinks. Sounds like they lucky missed (probably down to the extensive experience on type of the Captain) the third mistake that could have caused a tragedy. Too many holes in perfect aligment there lucklily the last one like their elevators hinges was blocked or the story would have be quite different i suspect. For sure he was under pressure to GO but deep down he suspected he was pushing his luck - hand flying and not using the A/P to make sure things were OK I wonder being a contractor - if he would he not get paid if he had backed out of taking that flight at such short notice. |
Pity when an elder captain has a do like that.
Good reminder that we can all make poor decisions when ill and/or under pressure to go. |
Tis easy for me to say nowadays BUT I always remember(ed) taking off is optional and for sure i could not exist in these days of SOP's hand flying discouraged - positive climb gear up and A/P on - then the regular meetings with the THE BOSS to explain why you did THAT!!! OK i was never one of the quiet ones and more than once said we are NOT GOING for various reasons. Once when we had been sitting too long in snowy conditions in GLA after we had been de-iced - What is the problem Captain you have been de-iced - well look at the wings will you i want her de-iced again. The dynamics are all wrong now those on the ground from C/P to Accountant have too much power now and are only focused on the bottom line NOT that this is a problem - Commercial concerns have to be considered of course but not to the exclusion of everything else - the days of the Captain being King are sadly long gone.
I only do yacht delivery trips now and for sure i wont go if i think anything is wrong sailing to someone elses deadline is another silly way to die. |
Turboprop icing
I've always had the impression that turboprop are more prone to experience icing problems than small GA aircraft or jets. Could anyone please comment on what the causes are?
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Would a simplified generalisation be that small GA aircraft are not flown much in icing conditions, and jets fly above them?
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Quite correct. Also flying around at 250 KIAS or more does wonders for ram air temperature rise so even as jets fly through icing areas, much less of ice clings to airframe than it would at typical turboprop climbing speeds of 140-210 KIAS. Not to mention media hysteria that every time turboprop crashes brings stories like "Turboprops are flying coffins in ice!". I suppose that Joe Publics who still remember Colgan disaster mainly think it was ice related.
This incident is a wonderful example of experience vs. knowledge. Capt was 63, he was TRE, he had 12 000 hrs, 4000 on type, he was formerly employed by BaE. And yet he decided to take-off with snow merely swept away from the airframe and with no anti-icing fluid on the aeroplane, despite the snowfall. Of course it's best to be both knowledgeable and experienced, but even the members of 10000hrs+ club sometimes have to do something for the first time in their flying careers. Outcome tends to be better if they know what they're doing. |
Clandestino - I think your second paragraph is a liitle harsh? Yes, the guy made an error of judgement, but as hinted at above, there may well have been several other 'errors' in the chain behind him which may not have been addressed. He will undoubtably have 'learnt' from this (indeed, one never stops 'learning') but have the 'others'? Was there a collective sigh of relief "Whew, we got away with it".
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The need to De-ice
The whole of an aircraft needs to be de-iced prior to take off, either by fluid or manually, otherwise safe flight cannot be assured.
In the past, in Far Eastern Russia, when the fluid had run out (sometimes by drinking), it could take up to four hours to manually de-ice a Corporate jet sized aircraft prior to departure. It was a welcome time when we obtained a heated hangar! Tmb |
BOAC, you have it one. I know the Captain concerned and would fly with him anyday. And if there is anyone who will have searched his soul over this event, its him.
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Clandestino,
To be fair, this may not have been something he was doing for the first time. Reading the AAIB report he decided that the aircraft needed de-icing and he decided on a method by which it could be done. He asked the local engineering contractor to carry out this service, and accepted a thumbs up from them as being that the work had been done, assuming that it included the tail surfaces. He should perhaps have bothered to get out of his seat and open the door and talk to them, or open the window and do the same to get a proper report, but other than that his decision that despite the weather there was no problem with hold over times so anti-iceing wasn't needed seems to be borne out by the fact that there were no deposits on the wings when they got airborne, so if the tail had been de-iced also the event would not have occurred. I am also a member of the "10,000 hour club", and it doesn't mean you always get things right, that is why you have someone, normally a member of the "less than 10,000 hour club", sitting next to you so you can spot each others mistakes. But in all the times I have sat in the left hand front seat of an aircraft during de-icing, or boarded one which has been de-iced, I have never asked for the loan of a cherry picker or other means to inspect the tail, and no F/O has suggested that I should -I have inspected the parts of the airframe that I can reach or see, and taken the report from the de-icing crew that the job has been done properly to mean that it has. This appears to be an issue as much for Eastern and their de-icing contractor at ABZ as anything else - if they cannot provide the service required because of a lack of de-icing rigs then the airlines quality department, which presumably also audits contractors, should be discussing with them the need for more equipment and proper training if they wish to keep the contract. |
DE-ICE
Well said Excrab, that clears a lot up.......... I think everyone should
be reminded of Rudi Kapustin's (NTSB) words about ice on the airframe = people are going to die...... |
It is always funny to hear the stories about de-icing from old times in Russia.
"People had been drinking de-icing fluid ....". The Russian Arktika Fluid, at these times the only one available, had been made out of Di-Ethylene-Glycol. 100ml would kill a big man with a weight of 100kg. So, I would suggest to stop such stupid stories. I am dealing in these countries when they still had been in the USSR and 95% of the stories I hear are simply "bla bla bla". Reality is: Every pilot, who is taking of an aircraft with a contaminated wing or flight controls or any other critical surface is risking the life of crew and passengers and the loss of the aircraft. His/her licence should has to be taken immediately. But not only focus on the pilots. Before 1998 mainly engineers made the treatment job and final check, now we often have absolutely unqualified ground staff doing it. In such a case the flight crews need to do a little bit more extra, if possible. The commercial aviation business (not counting the former USSR) lost more than 70 aircraft because of icing up, or improper de-icing/anti-icing in the last 30 years. There is no room for "stories", to serious. And no not kill me for this statement, it is true: Pilots of business jet operators or corporate flight squads are the ones with the lowest knowledge. |
EXCRAB
But you face a major problem in a lot of airports: You often have only one service provider and you are forced to take the service as it is or you will not fly.
Especially business jet operators have to deal with this problem on a daily basis in winter. But exactly most of them are not spending a minute and a dollar on an audit program. Look on the statistics and you will see that the last three accidents happened in the range of business jets: - Moscow-Vnukovo, February 2007, CL600 - Almaty, December 2007, CL600 - Yerevan, February 2008, CRJ200 A lot of these operators do not have the most essential things: - training for flight crews - updated hold-over-time charts - list of qualified fluids - and some more Being in this business for nearly 20 years, the standard in a lot of places is going down and does not improve at all. A lot of pilots are forced to deal with such conditions and do it, meaning they fly. I know only a few guys who step out of the cockpit and say "NO". |
What more reason than this do you need to de-ice?
S1/2002 - Bombardier Challenger CL-600-2B16, N90AG AAIB Bulletin No: S1/2002 Ref: EW/C2002/1/2 Category: 1.1 Aircraft Type and Registration: Bombardier Challenger CL-600-2B16, N90AG Serial Number: 5414 Year of Manufacture: 1999 Date & Time (UTC): 4 January 2002 at 1207 hrs Location: Birmingham International Airport Type of Flight: Private (FAR Part 91) Persons on Board: Crew - 2 Passengers - 3 Injuries: Crew - 2 Fatal Passengers 3 Fatal Nature of damage: Aircraft destroyed Commander's Licence: FAA Airline Transport Pilot's Certificate Commander's Flying Experience: Approximately 10,000 hours (of which about 500 were on type) Information Source: AAIB Inspector's Investigation History of the flight The aircraft arrived at Birmingham Airport on 3 January 2002 at 2039 hrs after a non-stop international flight from West Palm Beach Airport, Florida, USA. The Birmingham METAR for 2050 hrs indicated that the surface wind was from 120° at 6 kt, visibility 8 km, no significant weather, temperature minus 1°C, dew point minus 2°C, QNH 1026 mb. On arrival, the commander stated that the refuelling could be done the following morning in time for the planned 1200 hrs departure to Bangor Airport, Maine, USA. The aircraft was parked overnight on the Western Apron. The same 2 pilots and 3 passengers were to board the aircraft for the accident flight the following day. There was no precipitation while the aircraft was at Birmingham. The air temperature remained below zero with a minimum temperature of minus 9°C at 0550 hrs. Initially, the sky was clear but the amount of cloud increased to give variable cloud cover after midnight. The surface wind remained south-easterly at less than 5 kt. The next morning, one of the crew, together with one of the passengers, arrived at the aircraft at approximately 1040 hrs. The commander arrived at approximately 1100 hrs. At different times, each crew member was seen to carry out an independent external inspection of the aircraft. Aircraft refuelling commenced at about 1105 hrs and the aircraft fuel tanks were reported full (20,000 lb) at about 1140 hrs. Then, following the arrival of the remaining two passengers, the aircraft doors were closed. During the morning, other witnesses stated that they had seen frost or ice on the wing surfaces of N90AG prior to departure. Other aircraft, which had been parked overnight, were de-iced during the morning, with associated reports of moderate to severe ice or frost accumulations. Neither crew member requested de-icing, so N90AG was not de-iced prior to departure. The Birmingham METAR at 1150 hrs indicated that the surface wind was from 150° at 6 kt, visibility 8 km, scattered cloud, base 700 feet agl and broken cloud, base 800 feet agl. The outside air temperature was minus 2°C with dew point minus 3°C. The QNH was 1027 mb. There were no ATC flow restrictions to affect the flight and ATC start clearance was obtained immediately on request. The engines were started at 1156 hrs and N90AG was cleared to taxy at 1201 hrs. The preceding aircraft movement on Runway 15 was a landing BAe 146 aircraft about one minute before N90AG's departure. The previous departing aircraft had been an Embraer 145 a few minutes before that. At 1206 hrs, N90AG was cleared to line up on Runway 15 and at 1207 hrs take-off clearance was issued with a surface wind from 140° at 8 kt. The pilot in the left seat was handling the controls and the commander was seated in the right seat. Flap 20 had been selected for take-off and the following speeds had been calculated and briefed by the pilots: V1 137 kt; VR 140 kt; V2 147 kt. Initial post-accident assessment has shown these speeds to be appropriate to the estimated weight of the aircraft. Flight recorder information The aircraft was fitted with a solid state Cockpit Voice Recorder (CVR), and a solid state Flight Data Recorder (FDR). All available data was successfully recovered from both recorders. The take-off appeared normal up to the time of lift-off. Rotation was initiated at about 146 kt with an initial pitch rate of approximately 4°/second. Lift-off occurred 2 seconds later, at about 153 kt, with a pitch attitude of about 8° nose-up. Once airborne, the elevator position reduced from 8° to 3° (aircraft nose-up) whilst the pitch rate increased to about 5°/second. Immediately after lift-off, the aircraft started to bank to the left. The rate of bank increased rapidly and 2 seconds after lift-off the aircraft had reached 50° left wing down. At that point, the aircraft heading had diverged about 10° to the left. Opposite aileron, followed closely by rudder, had been applied as the aircraft started banking; full right aileron and rudder had been applied within 1 second and were maintained until the end of the recording. As the bank angle continued to increase, progressively more aircraft nose-up elevator was applied. The last recorded aircraft attitude was approximately 111° left bank and 13° nose-down pitch. Initial analysis of the FDR parameters indicated that both engines were functioning normally from start-up until the end of the recording. There was no indication of any abnormality which could have accounted for the uncommanded left roll. The CVR indicated that the crew members were operating normally with no apparent time pressure. The left seat pilot was handling. There were no audio warnings activated until shortly after take-off when the automatic voice "Bank Angle" sounded; this occurred within 2 seconds of the end of the recording. From the CVR, there was no indication that the aircraft's Wing and Cowl Anti-ice systems were selected ON prior to take-off. Initial engineering investigation Witness marks indicated that, following lift-off, N90AG first made ground contact with its left winglet. Initial contact had been onto the tarmac-surfaced left shoulder of the runway, approximately 1,415 metre along the 2,605 metre runway (Figure 1). The runway marks and wreckage damage characteristics showed that the aircraft had been banked approximately 80° left at this point and had been descending at a comparatively low rate. After initially tracking 10-15° left of the runway heading, the winglet scraped across the left edge of the shoulder onto the grass-covered ground adjoining the runway. Ground contact became progressively heavier, causing the outboard part of the left wing to progressively deform and breakup, while the aircraft continued to roll to the left. After the left wing had scraped for a total of 120 metres, fuel released from the ruptured wing tank ignited. At the same time, the forward, upper, left part of the fuselage contacted the ground heavily. This caused severe damage to the upper portion of the forward fuselage, structural severance of the forward fuselage at the front of the wing centre section and localised rupture of the right and centre wing fuel tanks. Shortly thereafter, horizontal stabiliser ground contact caused detachment of the fin from the fuselage and thus separation of the whole empennage. The main wreckage, consisting of the wings and the centre and aft fuselage, slid inverted for approximately 320 metres from the fuselage ground contact point before coming to rest. The remains of the forward fuselage remained attached by cables and pipelines to the main wreckage, in approximately its normal relative position, but came to rest upright. The Airport Fire Service was in attendance less than 1 minute after the aircraft came to rest and within a short period extinguished a substantial fire centred in the forward fuselage area. After on-site examination with the assistance of the aircraft manufacturer, the wreckage was moved to the Western Apron for further examination and to prepare it for onward transportation. The wreckage has now been moved to the AAIB at Farnborough for more detailed inspection. Effect on airport operations The airport was closed from the time of the accident until 1200 hrs on 6 January. Aircraft operations could not be recommenced until the crash site had been searched and examined in detail, as a large part of the wreckage trail was located within the runway cleared and graded area. This area was then required to be completely cleared of debris. This work had to be done primarily during daylight hours. The search and recovery operation was expedited using extensive resources from the West Midlands Police in co-operation with Birmingham International Airport Ltd and the Royal Air Force Aircraft Recovery and Transportation Flight. Future investigation The Chief Inspector of Air Accidents has ordered an Inspector's Investigation into the operational aspects.circumstances of this accident under the provision of the Civil Aviation (Investigation of Air Accidents and Incidents) Regulations 1996. Investigation work will continue on engineering and |
Madbob - can we bring this back to reality? Are you suggesting this "63 year old, TRE, 12000 hour etc etc" is not aware of a 'reason to de-ice'? The BBC headline was actually incorrect, and should have read "had not been properly de-iced" which is what the news item goes on to say - quite different?
I do not have any enquiry results available, but comments are 'no anti-icing fluid' was applied, "he did not inspect the tail" etc. Re-read excrab's post. Without knowledge of detail here, why is it assumed that 'anti-icing fluid' was needed? Was precipitation falling or forecast before departure? I have often just 'de-iced' with no anti-ice. In my airline time I have always accepted the 'ok' of the de-icing operative that it has been done correctly and NEVER gone out to 'check the tail' or whatever - common standard practice in many operations. So, was there a misunderstanding between the crew and the de-icers? Did the ground-staff fail to do their job properly? To 'hint' that the Captain somehow 'failed' in his duties is a little strong, in my opinion, without a little more evidence. I would tend to apply 'benefit of the doubt' here"! |
BOAC
Whenever you spray a fluid on your wing it is also an anti-icing. A de-icing process would be only possible with pure water only and this is not approved by any authority. Most pilots are forgetting that they have something on the wing, which may re-freeze, even no active precipitation is present. Very often the wing temperature is much lower than the OAT and well below freezing point. This can cause the fluid to freeze and you have no longer a clean wing.
It is a wrong assumption, I "made a de-icing only". This would only exist, when your temperatures (OAT and surface) are well above freezing point. Which in most cases never happen in winter. Several larger airlines made a wing temperature test programme a few years ago. I had been one of them being involved and I can guarantee you, that your wings stay much longer on cold temperatures you expect. As a flight crew member you have to take the fact that whenever fluid is sprayed on your wings you better calculate hold-over-time. |
A couple of points
1. I am very, very glad that everyone got out of the mess without as much as a scratch.
2. It is beyond any doubt that captain's exceptional skill and level-headness saved everyone once elevator got frozen. 3. Mechanical removal of snow or slush from aeroplane's critical surfaces can be used only as a method of reducing de-icing fluid consumption. It can't be acceptable as a sole de-icing method. 4. During snowfall it is :mad:ly dangerous to take-off without aeroplane being properly anti-iced and/or with hold-over time exceeded. Even if local de/anti-icing facilities leave a lot to be desired, when the wings are not green it is a no-go. Orange wings don't last long in heavy snow and sleet. 5. That there was no explicit warning in Operations manual about de- and anti-icing methods is organizational error which facilitated the crew's error. However, following the somewhat deficient official papers blindly can easily put you in situation described by Richard Bach as: "Everyone else is responsible, you are just the guy that does the dying." Very sorry to disappoint you BOAC, AAIB report is here. Captain was let down by both his training and his company. |
excrab: Agree. even if you are a 20,000hrs club gang you can oversee certain procedures. You assume that the G/E or handeling agent has done his job. I still have to see the metar for that flight or ATIS, to see the whole picture. Whatīs evedent is that a clean wing, tail and fuselage should be clean under known weather conditions. Donīt know much about the 41 but, it looks like it has some deice-boots? We always learn!!
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Thank you for the link, Clandestino - I agree that 'mechanical' deicing was not adequate and I see that snow was falling. My opinion revised!
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A little cautionary tale which I've related previously.
We operated B757 aircraft to an airport in Southern Israel. Our company policy was to carry round trip fuel. We arrived there in relatively cool, humid conditions. No surprise when cold fuel caused frost to form on the upper surface of the wings. I asked for de-icing but there was no de-icing fluid and, in my absence, the handling idiot threw buckets of hot water over the wings. We now had a quantity of ice on the surface which I found aforementioned clown trying to scrape off. It took some time transferring fuel around and refuelling to melt the ice off. On return I reported the incident and pointed out that, notwithstanding company 'policy', I would not be taking full round trip fuel in the future. Thank heaven for a proper airline and BALPA. |
Every time I drive past Pau airport here in South of France, I'm reminded about the need to de-ice. The sorry looking aircraft still sits at the end of the runway on stilts with engines and Air Chance livery removed!
http://images3.jetphotos.net/img/2/1...1243332411.jpg Passengers and crew were lucky to walk away from this one, The driver of the lorry that they hit.. not so. http://www.airdisaster.com/photos/f-gmpg/1.jpg |
.....and the season is upon us again! Seems ironic that the manufacturers have to remind operators to read their cold weather supplements EVERY year!
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I would suggest that accepting a "thumbs up" or any other indication for that matter from ground crew as evidence of satisfactory achievement of de/anti-ice treatment might not always be wise?
In many cases the operatives of the anti/de-ice rigs are simply diverted from a/c cleaning/water/toilet duties to operating the rigs. As such they may not have the training/experience to make judgemental decisions on ice clearence. Any signal you get from them simply means they've completed the task. |
On many jet opps you have no choice than to accept the deicing crews word. Once the door is shut and the stairs removed you can't just get out and have a look. Even on a small jet, the tail is normaly way too high to look at unless you are in a cherry picker. Many of the airports I fly to in winter have remote deicing. This means you taxi there to get deiced on the way to the take off point, so you have no chance to check over the outside. With the locked door policy, you can't even go in the back to look out of the windows without major hassel.
Seeing the F100 on the page above reminds me of a time when one of my flights almost suffered a similar fate. I too was an F100 Captain at the time, the aircraft had stood out overnight in snow that had later frozen. The policy was to board passengers, close the doors, remove the bridge, then deice before push. This was all done and we wre holding for a slot. The senior cabin crew member came into the flight deck (pre 2001) and said there was an F/O who was traveling as a passenger in an over wing seat. He asked her to mention his concern to me over ice still on the wing. We had stairs brought to the aircraft and I went outside to check it over. There was so much frozen Ice on the wings we would have probably never been able to fly. We had to deice again, we all lived to fly again and the engineer resposible lost his job. We still have to rely on staff outside to confirm the job has been done properly, but after that I have always been much more careful who to trust. |
Phil Capron
Just a short note to question the comment about de-icing above (Feherto post 20).De-icing and anti-icing can be achieved with a one step or two step process depending on fluids available,temperature,precipitation and holdover time reqd. etc. etc.
De-icing is the first stage of a 2 stage process and is never carried out with water but one of a number of recommended fluids usually cold(?) It is wrong to say de-icing can only be achieved with water.Check it out. It is also slightly misleading to state whenever you spray a fluid on a wing it is anti-icing.Given the wrong set of conditions/fluid it could seal your fate. Happy take-offs! |
De-Icing Tables, Cold WX Ops
With the advent of the northern winter, it may be timely for all pilots (and maintenance organisations, including contract ground staff) to review their company's cold wx ops; go to:
Holdover Time (HOT) Tables - Commercial and Business Aviation - Airlines & Aviation Operations - Air Transportation - Transport Canada (it is updated each August - last year it included a section on take-off with PL precip (ice pellets) |
Having had de/anti ice fluid refreeze in the elevator section, I am not necessarily sure that mechanical means of deice are not at times superior. Where dry snow is the contaminant, I would much rather use a broom, ropesaw, leafblower etc.....
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Hi Phil, please read my comment correctly.
1. Water is never allowed as one-step only. 2. Water is allowed as first step in a two-step procedure down to an OAT of -3° C. 3. It must be always observed, by flight crew and ground crew, what is the wing temperature and take it into consideration, when lower as OAT (which is very very often the case and people to not realise it). 4. Every time you spray a fluid on the wings it is a anti-icing. No way out and you must observe hold-over-time,including all requirements (e.g. fluid buffer 7° C for T2/T3/T4 and 10° for T1, 60° C fluid temperature at the nozzle mandatory for T1 and minimum 1 liter per squaremeter. If you know a case, where it is not an anti-icign having fluid on the wings, please let me know. It would be a brand new thing for me. Kind regards and have safe flights. |
de-icing at Newark
25 years ago, I was only a passenger, sitting in a blizzard on the tarmac at Newark N.J. waiting to return to the UK. Some sort of tower with a squirting arrangement started on one wing of the 747. Proceeded in a methodical manner around the aircraft. By the time they had squirted the other wing, I was upset to notice that the first one was now pebbledashed, which didn't seem right. And when they started up and began to taxi, I got very concerned and asked the cabin crew to have a look, the cabin crew got concerned as well, and called for the first officer, who came back and had a good look and said don't worry, dear, there is a de-icing tower just before takeoff. So there was, and in no time we were clear of the snow.
But nobody got out to check on the tail, and I can't imagine aircrew getting out to have a look under normal circumstances. If the ground staff at the airport are disorganised, who can you trust? |
Doesn't excatly have to do with the incident which started this thread, but thinking of the CL604 that crashed in Almaty on Dec. 25th 2007, killing the F/O, reminds me of watching very closely whom you can trust and who you shouldn't!
Whatever the personnel in Almaty poured onto the airframe that night was not meant to protect an airplane form ice accretion... |
Jetopa,
where do you have that info from? The bfu hasnīt got anything on this accident (or Ididnīt find it) I have seen the wreckage in UAAA.... |
BA Airbus Oslo thread continued !
As we enter colder weather I find it odd that the PPRUNE Mods give in so quickly to peer pressure from those who should know better regards airframe icing.
Yes Jet Jockeys tend to experience less of it but ATC can keep you low and slow in less than ideal conditions. Ice accumulation on the top surfaces of a wing have a huge effect on lift and drag: Gander : The Untold Story - Canadian Aviation Safety Board Majority Report "AC 20-117 identifies that the effects of ice formation on an aircraft are wide ranging, unpredictable, and dependent upon individual aircraft design. It states that wind tunnel and flight tests indicate that when ice, frost, or snow, having a thickness and surface roughness similar to medium or coarse sandpaper, accumulates on the leading edge and upper surface of a wing, wing lift can be reduced by as much as 30 per cent and drag can be increased by 40 per cent. These changes in lift and drag will significantly increase stall speed, reduce controllability, and alter aircraft flight characteristics. It identifies surface roughness as the primary influence in the decrease in lift and increase in drag and emphasizes that take-off not be attempted unless it has been ascertained that all critical components of the aircraft are free of adhering snow, frost, or other ice formations." It seems the AAIB could not determine how much ice was formed at the time of this incident. The pilot's were absolutely right to increase approach speed. Buffet WAS felt by the crew. It is highly likely the greater proportion of ice fell off approaching 500 feet restoring a/c to near normal L/D. This comment from the AAIB report is mere speculation: "It is probable that the buffet experienced was due to ice accretion on the top surface of the wings, as suggested by the manufacturer, and was not pre-stall buffet." It does not state the conclusion was an Airbus Test Pilot's view. It sounds more like a tech person based his V speeds on a clean wing rather than the actual conditions at the time of the approach. |
pressure
Lets get back to the good old days (if they ever really existed ?) when safety ruled over commercial pressure & if the weather was bad or icy no one flew. Oops, I had my rose tinted spec's on, back to reality !
I'm very pleased they all landed safely & survived the incident ok, hats off to the crew who, as per usual, performed a professional job under extreme demands. stay safe folks |
Your Dudeness,
in the examination of the accident that I was referring to, neither the accident investigators of the country where the a/c was registered in (hence the German BFU) nor the Canadians (because it was a Challenger) ever got access to the FDR or voice recorder. They were sent to Moscow. They were not allowed to take samples of the wreckage either. The de-icing truck was empty, making any analysis of its fluid worthless. My information comes from people who were actively involved in the accident itself and otherwise directly affected by its outcome. That must be enough. Lost a friend there. Don't want to capitalize information publicly, but merely share my personal opinion that in the oncoming months it might be a pretty smart idea to watch the people closely who are handling our airplanes and on whom we sometimes have to rely. |
DeIcing Done Right
On my way back home as SLF I was rerouted through ORD one March evening when the Easterly winds were dumping sticky snow from Lk. Michigan over everything.
The fluid was applied at the gate and was quite thick and warm. Then we joined a conga line to the rwy while the fluid accumlated a layer of snowflakes and came to look like a fuzzy baby's blanket. Turned on to the rwy and as the a/c accelerated the whole mess slid off like a blanket being pulled away:ok: My only concern was that there must be quite an accumulation of deice fluid sitting on the runway that the gear rolls through and I wonder if the engines take any of it in? |
RatherBeFlying;
The fluid was applied at the gate and was quite thick and warm. Then we joined a conga line to the rwy while the fluid accumlated a layer of snowflakes and came to look like a fuzzy baby's blanket. Turned on to the rwy and as the a/c accelerated the whole mess slid off like a blanket being pulled awayhttp://images.ibsrv.net/ibsrv/res/sr...ies/thumbs.gif Environmental issues are significant, mainly in the de-icing/anti-icing areas such as a centralized de-icing facility. Many have fluid recovery systems but that's a recent innovation. The Air Canada Pilots Association in Canada held a "Winter Operations" Safety Conference in Toronto at which a great deal of information was presented on these and other winter ops issues. ANY contamination on a wing is high risk, with outcomes depending upon aircraft configuration, speed, pilot recognition and so on. Hard wings, (no slats/high lift devices) (Bombardier Challenger, CRJ etc) will not tolerate any wing contamination whatsoever. On takeoff, hard wing (no slats) contamination even by less than a millimeter of frost or mere surface roughness will cause leading edge flow to separate violently, well below the expected stall speed; separation is exacerbated by a snap/fast rotation technique, (> 3deg/sec). Typically, pilot reaction in all accidents to date was to pull back instead of lowering the nose, sealing the fate of the aircraft. Bank angles at takeoff typically reach upwards of 110deg left or right almost instantly, as shown in available animations of these events. The key is de-icing, then anti-icing, and where conditions are uncertain, not assuming that there is no contamination. The only way to do that is physical inspection, (not just looking, but hand on the surface). |
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