AF447 – the Air Caraibes story and more on pitot tubes

Thumbnail image for AF A330 fin.jpg

This post is mainly about A330 pitot tubes and in particular the educational story of two nasty icing incidents at A330-operator Air Caraibes which I relate below. There’s no getting round the fact that the pitot issue has to be a major focus of the investigation until proven otherwise – but I would say now that in the long term it may not be the primary issue. That, I suspect, is more likely to be the question of how this aircraft came to be in the middle of a storm in the first place. We shall see.

Anyway, meanwhile back to pitot tubes, which it’s now reported that Air France is going to replace within days rather than weeks following pressure from its pilots’ unions SNPL and the much smaller ALTER. Seems there may be EASA action too.

Sources in the unions are putting it about that there have been quite a few pitot icing incidents on A330s, which I don’t think is disputed by anyone. And it turns out that two of them, in August and September last year, are unusually well documented.Air Caraibes Atlantique is a Paris Orly-based airline that flies twoA330-200s and two A330-300s to the French territories of Guadaloupe andMartinique. In a lengthy memo (full, complex, and  French text below)company flight safety officer Hugues Houang describes how bothA330-200s (F-OFDF and F-OPTP) encountered severe icing in virtuallyidentical circumstances on flights between Paris and Martinique atFL350. He tells the story of DF in detail, but says the two weresimilar.

The aircraft climbed 300ft in an unsuccessful attemptto clear the icing turbulence, then encountered severe turbulence and reduced speedaccordingly, and then suffered pitot icing – identifiable because thedetected temperature climbed to the temperature of the ice (-5C)instead of the so-called total air temperature (-14C TAT – airtemperature plus air friction heating).

Over the next 2-3minthings got quite unpleasant, with multiple warnings reminiscent ofAF447 and a period in alternate law. The crew appears to have done agood job working their way through the <unreliable speedindication> checklist facing a welter of ECAM messages and a stallwarning among other things.

Everything eventually ended happily,and what then happened was that “the management very rapidly decided toimprove the safety level of our flights by modifying the pitots on therest of the fleet”. The fix was to replace the Thales pitots, partnumber C16195AA ,with part number C16195BA. Here’s what Thales saysabout them in its literature.


Thales pitot leaflet.JPG



UnsurprisinglyAir Caraibes then requested a meeting with Airbus and the main pointthey raised with them is very interesting. Not the pitot issue itself,but “we stressed the difficulty encountered by the crew in using the<unreliable speed indication> checklist”.

You can probably see why in the the full text below on p.12even if you don’t read French. In different places Airbus haspotentially contradictory advice regarding stall warnings in thesecircumstances which is extremely difficult to reconcile in the coldlight of day and harder still in severe turbulence with the ECAM doingits thing.

Houang concludes: “Despite these contradictoryaspects the pilots of DF knew how to react the two inappropriatestall-warnings. Furthermore the Airbus engineers understood all thedifficulties encountered by the crew in applying rapidly andeffectively the <unreliable speed indication> procedure.”

Hesays the engineers agreed to consider modifying the checklists and attime of writing on 8 December last year he was waiting to see whathappened.

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29 Responses to AF447 – the Air Caraibes story and more on pitot tubes

  1. Richard Chandless June 9, 2009 at 5:32 pm #

    Apart from exploding fuel tanks or bombs few air accidents have one source. The root initial root os usually flawed decision making coupled with at least two further complications resulting in the crew no longer being able to cope. At first sight though it is alarming to think that a modern airliner can fly into a cloud and come to bits! Especially since it would appear that there was no abnormally adverse weather around.

  2. Simon Gunson, NZ June 10, 2009 at 12:31 pm #

    I take your article’s point that ultimately the question of blame may not revolve around pitot tubes at all.

    Icing in pitot tubes undoubtedly was the start of a cascade of problems. That is probably the cause, but the real question must be asked, why would a crew who could probably see this line of CB cells ahead for half an hour before reaching them not take any serious avoiding action, but ploughed straight in ?

    An Air Iberia A340 about the same time diverted east around the thundercloud system. Why did AF447′s crew not deviate at all ?

    Nobody is asking the real question.

    When people pay good money to fly on a plane they do so in expectation that the people sitting up front are professional and will take every professional precaution so that they can fly without fear or worry. The bond of trust which the public have always had for the profession of airline pilotage is being destroyed by increasing examples of pure incompetence by airline pilots. Colgan Air 3047 at Buffalo is a recent example.

    Pilots are very indignant at the finger of blame being pointed at their colleagues, but is time the self appointed and self rightious priesthood of pilots got real about their obligations to the wider community.

    Yes super cooled rain water got into pitot tubes at altitudes where water would not normally exist in liquid form, but as this Air Caribes example testifies, it was not an unknown problem. Just an unaddressed problem.

    The deeper and more meaningful question is what has become of judgement amongst airline pilots ?

    Simon Gunson

  3. C Moss June 10, 2009 at 2:12 pm #

    I do wonder if an issue in the industry is that airlines now seek management rather than pilot skills as the priority for selecting personnel. I’ve known magnificent pilots struggle for work because they are a little “independant” while people who treat it all as a glorified Nintendo game do rather well.
    All works, the Airbus or Q400 doing the flying bit and you doing the manageing bit, up to the moment it goes Pete Tong; when having the gimlet eyed god of the airways whose able to feel every nuance of a struggling aircraft through their finger tip and avoids trouble through huge experience can be very reassuring to we cargo out back!

  4. jbb June 10, 2009 at 8:07 pm #

    I don’t understand how there is certainty from the backseat pilots around the internet that AF447 did not attempt to deviate. The a/c was out of radar range, out of VHF range, and HF is highly unreliable to begin with, much less with rather large storm systems surrounding the a/c. What evidence could you possibly present that the a/c did not deviate an inch from its flight plan?

    In fact, all of the wreckage and debris so far has been found far west of its intended flight path. It’s possible that all of that movement was strictly from ocean currents, but it’s also quite possible that it was not and that, in fact, the a/c did deviate significantly. It’s possible that the severe electrical problem noted at the beginning of the ACARS correspondence knocked out their weather radar and that, while they were flying between CBs at the time, they were unable to determine where the CBs were moving and react accordingly (in conjunction with all of the ADIRU failures also simultaneously reported). Of course it is in our nature to speculate, but to claim that you know something for a fact that you simply do not, and to blame the flight deck (I’m sure, much to the chagrin of their grieving families) as well as other pilots for being “indignant”. You know as little as I do; we need to let the evidence come out as it will before we actually pass the judgment you seem so desperately anxious to pass.

  5. Rick June 11, 2009 at 3:55 am #

    I am a former military pilot, Comm. pilot, and 15 year a/c systems engineer. Long story short, I try to apply lessons learned from previous incidents/ accidents to aircraft design. I hate to say this, because of my background as a pilot, but no matter how fool-proof we try to make these systems, a ‘better fool’ comes along. We pilots keep allowing our brothers and sisters to get into situations they do not know how to handle (eg. Direct Law @Air France). Or, we are grossly negligent in preparing them sufficiently (eg. pulling the yoke in a stall @Colgan Air).
    The ultimate responsibility lies with the Chief Pilots of these organizations. I am not trying to be self-righteous here; I have been involved in several mechanical incidents, but having studied literally hundreds of accident reports, I had a ‘virtual’ body of experience far outweighing my own modest flight hours; which allowed me to compensate with no loss of life.
    1. Chief Pilots: train in excess of the minimums.
    2. Pilots: learn from accident reports. Quiz eachother. For example, choose two random items on the aircraft and discuss how they relate to each other.. they don’t? I bet you they do.
    3. Air Carriers: fulfill the ADs before they are due. Pay your Jr. pilots a living wage, train them better, and thus regain the faith of the traveling public.
    4. Flying public: spend a few more dollars to fly better/newer hardware.
    and on and on..
    Think about this.. Flying is very safe on a ‘per trip’ basis, but when you re-calculate the statistics on a per person-trip basis (like cars and motorcycles statistics), this multiplies the risk percentage by the average # of SOB; resulting in a truer, and higher assumption of risk.

    Leaving my soapbox now.

  6. Steve Gottlieb June 11, 2009 at 6:40 pm #

    To offer a possible answer to Simon’s question, the crew was likely loathe to divert around the known CB due to air-lane and traffic considerations. They flew their “lane” because they were out of radar range, so had no ground control, and probably thought from on-board radar that the CB in front was not as violent as it actually turned out to be. Radar is not always able to give good feedback on storm strength. They definitely knew that several other flights (some even Air France departures from Brazil) were traversing at similar times. Fear of mid-air collision probably resulted in the crew trying to stick as closely as possible to its assigned flight-path lane. One has to take into account that the CB in front of them was a long line of storm cells. Diverting around might well have involved going many miles off expected path, and likely across or into others’ expected paths. Not having capability to warn all potential traffic in the area via radio, they likely chose to stick with their expected filght path. With this consideration in mind, the crew probably tried to “thread the needle” between cells and simply missed.

  7. Richard June 11, 2009 at 10:49 pm #

    The relatively cheap little GPS I have in my car gives me constantly updated speed readings and verbal warnings if I exceed the speed limit. Why is that facility not available / not used on a commercial airliner?

  8. m. June 12, 2009 at 3:57 am #

    a/c stm show irregular readings of a/s when it start to descend..wonder whether due to instrument or sth else.Anyway
    nothing is perfect so is hardware software and human beings unless
    we are able to fly without the help of others
    l

  9. Steve Gottlieb June 13, 2009 at 6:09 am #

    My only follow up is to say that when the end of the line of storms is only 20 miles to the East of your flight path, its much easier to make the decision to leave one’s assigned lane. When one has ground control available, such as in domestic flight, the same applies. In international travel over water at night, sans ground coordination, and facing a line of storms that’s 50+ miles to either side, the decision to divert around becomes much more difficult, with other “unguided” traffic abounding.

  10. Johnny June 16, 2009 at 3:30 am #

    @Richard, because your car isn’t flying through mid-Atlantic cumulonimbus. However, in principal you are right, but the technology simply hasn’t caught up to you yet. The concept is there, but not the know-how. Not yet, anyway.

    If you’d like to be a multi-multimillionaire, then that is a good way to become one.

  11. Jonathan June 16, 2009 at 2:02 pm #

    Hi all,

    I do not comment that much on blogs. But in this case I can’t resist…
    For me there is no doubt that jbb is right. Nobody can say that it is a fact the crew just flew in a cell. Ofcourse it is tempting to think or speculate so but only the blackbox can give an answer to this question.
    @ steve: As a short haul pilot for one of Europe’s biggest carriers I got to know close to 500 captains by now. There was no single one that would conciously fly into a CB (needless to say the same will go for our FO’s). Even in Europe you will find yourself miles off track to avoid weather every now and again. In the ITCZ it is accepted by everybody that avoiding weather for miles and miles and miles is just part of the game.
    AF is a premium airline that has well trained crews, well maintained aircraft and a mature set of standard operating procedures (I do not fly for AF but still I think we can state this as a fact). For this reason I can not agree with you that it is likely they consciously flew into a CB out of commercial pressure or other “non operational” reasons.

    Best regards,
    J

  12. Steve Gottlieb June 16, 2009 at 9:10 pm #

    Jonathan,

    The facts simply do not agree with your assessment. I refer you to the reconstructed weather radar and weather assessment performed by Weather Graphics. This guy is a former Air Force Weather Routing specialist, who routed their heavy transports over international waters. He remains connected with Navy Sat Ops and Nasa’s JPL, both of whom provided contemporaneous sat data, and he also obtained AF447′s filed flight plan from the FAA. They had a line of CB cells more than 300 miles wide in front of them, with about 75 miles of storm thickness to fly through. Going around was not really an option, and you may also note that several other international flight lanes are marked proximate to the assigned lane for AF447 (UN873), such as UN866, UB623, UL375 and UN857. This was a potentially congested traffic point. See it all for yourself and judge:

    http://www.weathergraphics.com/tim/af447/

    Best regards,

    S.

  13. Cdr. Jim June 18, 2009 at 12:08 am #

    I have been out of the military flying business for about 30+ years now, but in my experience, we could communicate from five to fifteen thousand feet altitude in the cold, stormy North Atlantic to home base via LF or VHF freqs for up to (and more than) 1200- 1500 nautical miles ! Why can’t modern day A/C communicate with a comm. base at 30,000 – 40,000 ft.without atmospheric or electronic interference? Are modern aircraft that restricted that they cannot reach a comm. base less than 1,000 miles distant?
    Am I a relic of the past, or has the art of modern day communications regressed in the last 40 years?

    cdrjim

  14. zagorfly June 18, 2009 at 5:46 am #

    This is a tragedy.

    many people trying to understand what failed that night. I have some ideas:

    FAILING TO :
    1) dispatch a flight into such significant heavy weather
    2) acceppting the culture that we do fly “customers” Customers are more intersted in the wine selection then the weather
    3) flying too hight ot save fuel
    4) flying into narrow stall speed margin (coffin corner)
    5) for profit reason deploying aircrafts that are not designed to be Intercontinental range (ETOPS )

    event come too quikly up there nobody should be blamed except the industry that want to make people fly without wings .

  15. Jeremy June 18, 2009 at 11:38 pm #

    The issue is not why did the crew fly through a line of active CB’s. By all accounts there was nothing unusual about the weather.
    Whilst avoidance will always be the preferred option, crews are often left with no choice (be it due to traffic, fuel – whatever), other than to pick their way through this type of weather using their experience and weather radar to avoid the worst of it. It’s done safely every day around the world.
    The inadequacies of this particular pitot system being subject to icing on the A330 are now widely accepted.
    Looking at similar incidents on A330, the crew would have been unexpectedly faced with multiple and some irelevant ECAM messages in a very short space of time (<1min?), in addition to automatic A/P and A/THR disconnection.
    Past incidents show that in the space of a few seconds, the ECAM would show:
    - an airdata system fault
    - a caution to advise of degraded flight control laws
    - possible (spurious?) engine EPR faults
    - a fault with windshear detection
    - a warning to advise that the A/P had disconnected
    - a caution to advise that the A/THR had disconnected
    - a caution to advise of a rudder flight control limit fault

    All with the associated tones, bells and whistles.

    Shortly thereafter, they would have been executing the 'UNRELIABLE AIRSPEED' checklist which in which Airbus advises the crew to 'Respect the Stall Warning'.

    Previous similar incidents did have spurious stall warnings.

    If the crew reacted to this and followed Airbus recommended procedure, it could have led rapidly to an actual overspeed condition.
    With partial loss of the flight protection envelope due to the aircraft operating in 'Alternate Law' parameters and no accurate airspeed data, there would be nothing to alert the crew to the overspeed.
    The GPS is of little use since it will only show ground speed, not airspeed and the computations to determine airspeed require that you know the current wind direction and speed and allow for altitude correction. In any case – not enough time and too complicated in the time available to do it.
    Throw into this a dark and (literally) stormy night, lightning and turbulence and you have a recipe that could easily overwhelm even a competent and well trained crew, resulting in an inflight breakup.

    The real issue is why Airbus have such a complicated, time consuming and sometimes contradictory procedure to deal with a scenario in which you may have so little time to assess and handle the situation.

  16. Jonathan June 19, 2009 at 2:36 am #

    Steve,

    I saw the weathergraphics link before. That still does not give any proof of:
    1 Pilots consciously flying into a storm
    2 AF447 ending in this particular one

    As to point 2. Of course I see your point that it seems likely they ended up in the middle of these CB’s. But as stated before: the only proof will be the flight recorders. Without them every so-called fact is in fact speculation.
    See also http://www.flightglobal.com/articles/2009/06/17/328358/paris-air-show-french-investigators-release-af-447-search-details.html

    If, however, you want to speculate on the basis of the radar images on weathergraphics.com then you should keep following at the back of your mind:

    1 pilots do not knowingly fly into storms (trust me on this)
    Your statement that flying around the cells was “not really an option” is not correct. As stated before flying even 100s of miles off track is daily business, especially in the ITCZ. We (pilots) are trained to do so and calculate our fuel uplift accordingly. On top of that we know that flying into those clouds would be suicide.
    If we followed your theory of knowingly flying into CB’s we would be loosing and damaging aircraft on a daily basis. Which is a lot “more expensive” than an extra refueling stop every so and so many months.
    Note that the satellite images from weathergraphics are infrared images taken from above obviously. As the images one sees on his navigation display in the aircraft are not infrared and taken from another angle, the crew of AF447 will have seen a significant different image than that what we see online today.

    2 the only fact you have is that “intol” was reported
    The phrase “estimate sasil at 02:23″ only means that according flight plan the crew expected to be there at this time. It does not state a fact about the actual route of the aircraft after intol.

    3 after intol it seems that there is plenty of space to divert west of the core cells. The FACT that best part of the wreckage now found was North west of intol could indicate the crew did so. However, sea current makes it hard to judge where the bits and pieces actually did fall down.

    Best regards,

    J

  17. Jonathan June 19, 2009 at 4:05 pm #

    Good posting Jeremy. Sounds all very reasonable to me…

    Would be interesting to know if airbus is considering a change in the “unreliable airspeed” procedure. Considering that Air Caraibes also noted the very high workload for their crew in their “get together” with airbus one would expect and hope so.

    Best regards

    Jonathan

  18. Paul June 21, 2009 at 6:07 pm #

    All very interesting postings.
    After years of crash investigation, the fin and rudder that was found is a serious path … that look like the American Airlines AA 300 crash in 2001.
    So, I think the crew is not to blame…the weather was simply too bad for the fin and rudder assembly to stay with the fuselage…

  19. Steve Gottlieb June 21, 2009 at 7:31 pm #

    Jeremy and Jonathan,

    Interesting posts and debate. Thank you both for the dialog.

    SAR (not ACARS) at 0414GMT (2014Z) positions AFR447 just North and West of assigned flight path between INTOL and TASIL (just South and West of TASIL). The Brazilian Air Force (FAB), however, positions AFR447 on flight plan, and the BEA projects AFR447 only slightly West (3nm) of flight plan. See:

    http://countjustonce.com/af447/

    and

    https://www.defesa.gov.br/imprensa/mostra_materia.php?ID_MATERIA=33063

    The debris field, matched with ocean current trends (3/6nm to the North and North and West per day – see above site), supports the FAB/BEA positioning. As the article cited by Jonathan states, the debris was found within 55nm Southwest, West and Northwest of waypoint TASIL. For a more detailed indication of debris recovery points over time, see:

    http://www.bea-fr.org/anglaise/actualite/af447/sea.search.ops.pdf
    (at pages 5-10 of the PDF)

    I think its safe to say we are not speculating when we conclude that AFR447 predominantly stuck to flight plan. There is no indication these pilots tried to turn back or significantly alter course. After all, at INTOL, the pilot reported he was proceeding to TASIL, and by then, the crew would have definitely seen the CB weather ahead on on-board radar (regardless of what that specifically indicated to them about storm characteristics).

    A word about the difference between “proof” and “fact.” Proof is a much higher standard, which nobody can demand in this instance. Proof is absolute. Fact is established by evidence that most probably and convincingly indicates what happened. Since we are talking about events that happened over the ocean in the middle of the night, it is unlikely we will ever establish “proof” as to what happened. Even the advent of the “black box” would only add additional (strong) probabilities to the evidence in this case. The evidence we do have, however, strongly points to facts about what happened. In other words, fact is what reasonable minds will accept as the best possible version of what occurred, given the limits of investigation, instrumentation, scientific principle, mathematical extrapolation and observation. Speculation, or hypothesis, is our attempt to use the facts we’ve gathered to logically fill the holes in between, which we can never know to a virtual certainty.

    It is impossible to compare the procedures followed over land, with ground control, or in daylight, to those followed over international (uncontrolled) waters at night (Oceanic ATC rules). While I have no doubt about Jonathan’s procedures, because I take his words at face value, neither he or his company were flying that AFR A330 jet that night. I can’t reasonably apply his company’s stated rules to them. In a perfect world, all pilots would avoid all storms. But we know from experience that neither all pilots, nor the world, is/are perfect.

    A request to significantly deviate from flight path via HF would have been standard procedure for the manoeuvering Jonathan suggests was obligatory. No such call was made by AFR447. I cannot simply accept the proposition that these skilled AFR pilots violated a cardinal rule of piloting by failing to deviate. Numerous other major airline and commercial freight pilots disagree. Clearly, the A330 is built to fly through such weather events and the fact that checklists exist for accomplishing such flying militates strongly against a conclusion of “obligatory” diversion. Obviously, what the AFR crew did, in retrospect, turned out to be ill-advised. But was it outside standard procedure (or pilot discretion) without the benefit of hindsight? I strongly doubt it. If anyone can show me AFR-issued procedures that say otherwise, then I will certainly change my mind. Jeremy’s remarks, while recognizing avoidance as a preferrence, begin with the proposition that it is unremarkable to encounter such storms and to safely fly through them. I strongly tend to agree with Jeremy on this point.

    Based on calculations, the FAB-reported position has AFR447 flying at M.82 between INTOL and TASIL, even though the turbulence penetration guidance suggests that M.80 should be used. Deceleration to M.80 should have occurred at 0400GMT / 0200Z under normal guidelines. The French BEA-established position at 0410GMT / 0210Z is consistent with flight on assigned track at M.82. On-board SAT/GPS, reported by ACARS, which may be unreliable with systems failing, gives a more northerly and westerly final position, indicative of an overspeed at M.84.1 (groundspeed calculations are subject to many variables, such as altitude, tail or head winds, etc.). This gives cause for speculation that icing of the Pitot tubes produced a significant overspeed condition, leading to a potentially catastrophic rudder limit issue, which could theoretically rip the vertical stabilizer clean off (AP and Rudder Limit Control off per ACARS at 0410GMT/0210Z). I’d love to hear opinions as to whether the “respect the stall warning” guidance in the checklist, which Jeremy pointed out, could have added to the potential impact of the overspeed/rudder limit issue.

    Leaked coroner’s reports on the bodies found so far (50 or so) state that they present mostly contiguous bodies, with numerous internal fractures, all consistent with falls from a great height. Petichial hemorrhages are evident in their mucosa; a definite sign of asphyxia occurring, while alive. There is no mention of any burns. ACARS reports cabin decompression at 0414GMT. It is a well-founded conclusion that this plane came apart in mid-air. It is speculation as to why that happened. The proverbial “black box” is not the only instrument / evidence that can lead to well-founded conclusions of fact.

    Obviously, the point is to learn as much as we can about what happened to AFR447. This is so the flying public can be protected as best as possible, and so that those who tragically lost their lives in this incident will not have died in utter vain. Indeed, I am reminded, as a mere example, that three talented young Irish physicians perished. We should not lose sight of these terrible losses. While we may disagree on methodologies and procedures, I think we all agree on the end-goal: to give value to these victims’ sacrifices, and make flying even safer.

  20. John English June 23, 2009 at 5:04 pm #

    Simon Gunson you’re talking shit. Do they even have airplanes in NZ? Don’t start blaming the pilots even before all the facts are in.

  21. Keith Sketchley June 23, 2009 at 9:45 pm #

    There’s much to dig through to even begin to understand the systems and messages, and even the reports (Australian report + Air Caribe “en francais” and difficult to see online.

    ….Keith

  22. LuckyEddie June 24, 2009 at 8:21 pm #

    A lot of speculation going on here, only some of it informed. I just want to straighten out some things from a pilots perspective.
    1. Lack of a call on HF means nothing. HF is one of the least reliable means of communication available, especially in poor weather conditions. Inability to contact ATC on HF would not deter any pilots I know from deviating as required.

    2. The Satellite weather image is relevant only in showing that thunderstorms were in the area. The crew of AF447 would have had a far more detailed view of the weather directly ahead and at or below their level on their radar and may well have seen a gap that cannot be seen from above. They would not however, have seen this from INTOL! Airborne weather radar is just effective at about 160nm range, only really useful at 80nm, so it is unlikely they could have made any deviation decision whilst still within VHF range.

    3. Someone was wondering why the pilots did not have a simple speed readout such as is provided on a cars satnav. They would have, it is called groundspeed, and it would make sense to refer to this in such a situation, but it is not a complete replacement for airspeed. Indicated airspeed would differ from groundspeed by more than 100 kts at this altitude, plus (or minus) the effects of wind. For this reason it also cannot be used to generate warnings.

  23. Frank Elias July 1, 2009 at 1:29 pm #

    Hello LuckyEddie,

    Yes, you are right. The GS on the ND will always indicate correctly as it is derived from the GPS and would be a good speed reference to fly in the interim and one should not respect the stall warning; unless the GS also falls in proportion to the IAS.

    Stay Lucky Eddie

    Frank Elias

  24. Uninformed July 7, 2009 at 2:29 pm #

    All,

    From a member of the flying publics perspective…..is it possible that in conjuction with the many theories tabled, the storm cells were in fact ‘freak’. We all know about today’s weather patterns and how they differ from days of old. Could the conditions within these storm cells have exceeded aircraft design. Million to one chance sort of thing?

  25. Malcolm July 7, 2009 at 2:31 pm #

    Freak weather conditions exceeded those used in aircraft design.? We all know todays weather patterns have changed and in conjuction with the many theories tabled, this stotrm could have been the mother of all storms….possible?

  26. Unknown User October 20, 2009 at 12:55 am #

    57 feet 1 inch empennage exact equal match to (((57 feet 10.4132019388243802694370198729075 horizontal stabilizer)))

    0.104132370829788838820499999999967
    10.4132266697418009031661179499967 inches

    57 feet 2.2446629634617494 (2.4629~46835) 2.465625=2.66
    4.28-.00180=4.2682 2.67
    .0003365 furlong 2.665 average=44288377.77548 59.37 hertz to hectometres to 59.6 hertz from 57 feet of 684 inches from inches to leagues 118.97

    horizontal stabilizer for consideration 57 feet 10.41342451708116597299890256665 inches best stable setting
    477.774597325669031343614754819734
    59 1410712124795121210104
    59 548361 663347 59.58 (.42) hertz 1+.14_+.6 1.74+.6_.14=2.48 inches
    57 feet 2.48 inches
    avg-
    average for the horizontal stabilizer 31 requested by the plane would be the ((((}57 feet 10.41662480334545465316611794999 inches{))))this is where it is set now at the end of 2.47 for 1.996 inches from 57 feet 1 in empennage this distance needs to be verified with the actual plane of the Airbus a330
    avg-
    2.31+6(7) 16 1115 8( (4) 2.45 inches 9
    57 feet 10.41982508960974333333333333333 inches horizontal stabilizer distance half of the way to the maximum

  27. Kieran Daly April 7, 2013 at 11:05 pm #

    Steve touches on an interesting area, and it’s one on which airline pilots don’t all seem to agree. Some seem to be very happy with large diversions around storms, some seem to feel that there is a limit that they would be happy with and would not want to go beyond. Appears to me to be a slightly grey area???

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  29. Serena October 29, 2013 at 2:39 am #

    I don’t even know how I ended up here, but I thought this post was great.
    I don’t know who you are but definitely you’re going to a famous blogger
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