ModerateChop Posted February 15, 2009 Share Posted February 15, 2009 What about large turbojet passenger aircraft and tail plane icing ? Every Boeing I'm familiar with (B727, B737, B757, B767, B777) doesn't even have anti-icing/de-icing capability on the horizontal stabilizer. I've never heard of a tail stall due to icing contaminaton on these type of aircraft ? Turboprops are falling out of the sky all over the place yet the jets are certified without any tail plane de-icing capabilities at all. Why the difference ? MC Link to comment Share on other sites More sharing options...
dagger Posted February 15, 2009 Share Posted February 15, 2009 Autopilot was engaged at the time of the accident? http://www.theglobeandmail.com/servlet/sto...ernational/home Link to comment Share on other sites More sharing options...
UpperDeck Posted February 15, 2009 Share Posted February 15, 2009 On the news this evening, they reported that the auto-pilot was still engaged and that as a consequence, the PIC would not have "felt" the deterioration in flight characteristics. per Dagger today: "Autopilot was engaged at the time of the accident? http://www.theglobeandmail.com/servlet/sto...onal/home" Link to comment Share on other sites More sharing options...
Canus Chinookus Posted February 16, 2009 Share Posted February 16, 2009 I've heard they've ruled out a tailplane stall, and that it was a conventional stall. Link to comment Share on other sites More sharing options...
Guest woxof Posted February 16, 2009 Share Posted February 16, 2009 Ah yes, the wind tunnel experts. "...must be residual ice..." From people who sit behind a desk and design scientific experiments which, by definition can never fully duplicate real life phenomena. The quantum leap made from wind tunnel observations to observing, first hand the ice that forms while the boots are inflated, between the blocks of residual ice is illogical. By the way, the "recent conference" was more than 10 years ago if you look at the date of the CBAAC. Read what the FAA says "today": "Ice bridging: Classic pneumatic deicing boot ice bridging occurs when a thin layer of ice is sufficiently plastic to deform to the shape of the inflated deicing boot. This occurs without the thin ice breaking or shedding during ensuing cycling of the deicing boot. As the deformed ice hardens and accretes more ice, the deicing boot becomes ineffective. Ice bridging may occur when enough supercooled water freezes during the inflated deicing boot dwell period. It will keep that shape after the deicing boot deflates and will form a deformed surface that continues to accrete ice and is unaffected by ensuing cycling of the deicing boot. A deicing boot ice bridge may also form when flying into increasingly colder ambient temperature conditions following a mixed-phase icing encounter at near-freezing temperatures. Ice bridging also refers to the ice “caps” or “bridges” between adjacent component surfaces. For example, unprotected leading edge surfaces of an elevator horn and the horizontal stabilizer." http://forum.aeforum.net/index.php?act=ST&...=0#entry1531494 Here is what the NTSB said in Dec 2008 among other things on the subject.... "Ice bridging is extremely rare, if it exists at all." "The Safety Board has no known cases where ice bridging has caused an incident or accident, and has investigated numerous incidents and accidents involving a delayed activation of deice boots." http://www.ntsb.gov/alerts/SA_014.pdf Looks like you experienced one of those very rare situations. Link to comment Share on other sites More sharing options...
Kip Powick Posted February 16, 2009 Author Share Posted February 16, 2009 "Ice bridging is extremely rare, if it exists at all." The chance of simultaneous double engine failure on a twin engine aircraft is extremely rare, if it exists at all...(((ask Sulley)))...by DKP 'nuff said Link to comment Share on other sites More sharing options...
Guest woxof Posted February 16, 2009 Share Posted February 16, 2009 It is actually quite an important issue for the NTSB to dispel this myth or very rare event. It is on their most wanted list as seen below Most Wanted Reduce Dangers to Aircraft Flying in Icing Conditions -Use current research on freezing rain and large water droplets to revise the way aircraft are designed and approved for flight in icing conditions. -Apply revised icing requirements to currently certificated aircraft. -Require that airplanes with pneumatic deice boots activate boots as soon as the airplane enters icing conditions. "The Safety Board has no known cases where ice bridging has caused an incident or accident, and has investigated numerous incidents and accidents involving a delayed activation of deice boots." Link to comment Share on other sites More sharing options...
Kip Powick Posted February 16, 2009 Author Share Posted February 16, 2009 QUOTE]The Safety Board has no known cases where ice bridging has caused an incident or accident, and has investigated numerous incidents and accidents involving a delayed activation of deice boots." Link to comment Share on other sites More sharing options...
Canus Chinookus Posted February 16, 2009 Share Posted February 16, 2009 In my career, the closest thing i've ever seen to bridging was crappy boots not inflating properly, and therefore not shedding the ice. Link to comment Share on other sites More sharing options...
Moon The Loon Posted February 16, 2009 Share Posted February 16, 2009 "The Safety Board has no known cases where ice bridging has caused an incident or accident, and has investigated numerous incidents and accidents involving a delayed activation of deice boots." Since this flight had its boots running from very early into the flight, the condition I've described may very well have occurred. In which case, the shoe will be on the other foot. Their "no known cases" may turn into One. It will be a long time before we know. Link to comment Share on other sites More sharing options...
Guest woxof Posted February 16, 2009 Share Posted February 16, 2009 What about large turbojet passenger aircraft and tail plane icing ? Every Boeing I'm familiar with (B727, B737, B757, B767, B777) doesn't even have anti-icing/de-icing capability on the horizontal stabilizer. I've never heard of a tail stall due to icing contaminaton on these type of aircraft ? Turboprops are falling out of the sky all over the place yet the jets are certified without any tail plane de-icing capabilities at all. Why the difference ? MC Downwash over the tail with flaps extended is less perhaps on those aircraft. Just a guess. Link to comment Share on other sites More sharing options...
jump seat Posted February 17, 2009 Share Posted February 17, 2009 From today's Toronto Star "Ground turboprop aircraft, expert says" http://www.thestar.com/news/world/article/588565 Just a little overacting don't you think? Link to comment Share on other sites More sharing options...
Mitch Cronin Posted February 17, 2009 Share Posted February 17, 2009 What an idiotic reaction that would be. Link to comment Share on other sites More sharing options...
RGT Posted February 17, 2009 Share Posted February 17, 2009 The Aviation Herald Last Update: Tuesday, Feb 17th 2009 12:11Z http://avherald.com/h?article=414f3dbd/0010&opt=0 Link to comment Share on other sites More sharing options...
Guest woxof Posted February 17, 2009 Share Posted February 17, 2009 The Safety Board has no known cases where ice bridging has caused an incident or accident, and has investigated numerous incidents and accidents involving a delayed activation of deice boots." The key words.........no known cases Be it known .........I am not advocating one procedure over another but merely pointing out that the TSB is not infallible. You are certainly correct the the NTSB is not infallible. Several reports have been amended over the years for various reasons. I'm not sure where the quote on the double engine failure came from. However when one compares a statement an official report via thorough investigation leading to a statement in a most wanted recommendation saying.... "Ice bridging is extremely rare, if it exists at all." ....to what appears to be a media statement from someone answering interview questions(based on my ASSumption) saying..... "The chance of simultaneous double engine failure on a twin engine aircraft is extremely rare, if it exists at all..." ....one should take into consideration the context in which these statements were made and the background leading up to the statements being made. In other words.....a very thorough analysis over many years by qualified experts has been done for the ice statement and would be highly credible in its attempt to clarify the great unlikelyhood of ice bridging. Link to comment Share on other sites More sharing options...
DEFCON Posted February 17, 2009 Share Posted February 17, 2009 Bean With respect: "The track record is in job creation, no layoffs, profitability, creation of shareholder wealth, growth and never having a fatality or hull loss." Your prioritizations of the factors of airline success are contrary to most any airlines stated goals where, “safety” is always claimed to be a “first priority”. I would argue, fatalities and hull losses are quintessential to achieving the other items on your list? I believe your considerations as a non-pilot business exec are normal and expected. That is to say, because it’s not your area of expertise, you can’t be expected to “understand” the nature of the machine, nor those that fly them. Consequently, your pov is directly contrary to that of the pilot, the pure intent of flight safety programs and a demonstration of the tribulations those such as Captain Hudson have in convincing the guardians of the purse strings of the necessity of said programs etc. Link to comment Share on other sites More sharing options...
DEFCON Posted February 17, 2009 Share Posted February 17, 2009 Although I don't know much about this ac's design, on earlier models of the airframe, maintenance could easily make a "mistake" and install removed tailplane leading edges upside down. As you might guess, a mistake of this sort would have quite an impact on all the issues being questioned in the crash? Link to comment Share on other sites More sharing options...
CANCELIFR Posted February 17, 2009 Share Posted February 17, 2009 I don't think Bean was prioritizing, he was just making a list. Link to comment Share on other sites More sharing options...
Canus Chinookus Posted February 17, 2009 Share Posted February 17, 2009 I'll add another speculation. Is it possible they were distracted looking at the wings(or some other distraction) and discussing things that the PF forgot to monitor the instruments? Apparently there is no auto throttle system(please correct me if I'm wrong), and if not, perhaps the power didn't get increased as the amount of ice on the airframe increased(drag increased), and the speed slowly deteriorated until a conventional stall/spin occurred? I know it's grasping, but I don't think this possibility has been mentioned yet. Link to comment Share on other sites More sharing options...
ModerateChop Posted February 17, 2009 Share Posted February 17, 2009 perhaps the power didn't get increased It would be interesting to see the FDR plot of throttle position, engine power and airspeed. I'm sure the NTSB has this info. by now, but for some reason have not included it in their very selective and limited spoon feedings (press conferences). I wonder why ? Link to comment Share on other sites More sharing options...
Moon The Loon Posted February 18, 2009 Share Posted February 18, 2009 I'll add another speculation. Is it possible they were distracted looking at the wings(or some other distraction) and discussing things that the PF forgot to monitor the instruments? Apparently there is no auto throttle system(please correct me if I'm wrong), and if not, perhaps the power didn't get increased as the amount of ice on the airframe increased(drag increased), and the speed slowly deteriorated until a conventional stall/spin occurred? I know it's grasping, but I don't think this possibility has been mentioned yet. I've been told you might be so very, VERY close to the truth. Probably another day or two before it's made public. Not a good day for aviation.... Link to comment Share on other sites More sharing options...
Bobcaygeon Posted February 18, 2009 Share Posted February 18, 2009 My uninformed dash 8 pilot guess is that they were fast coming in (like most turboprops in a jet world "keep the speed up") then pulled the power back to idle at the last possible minute, they then dropped the gear and flaps as they slowed to the appropriate speeds then were distracted and forgot to bring the power up. The 6 bladed props in addition to the gear and flap would decelerate them very quickly causing them to stall if not caught. This situation to me is likely because the wx wasn't bad and nobody flies the Dash on the sim profile of 140kts while trying to operate in most ATC environments (especially in the U.S.) unless the wx is the shits Just my opinion Link to comment Share on other sites More sharing options...
Don Hudson Posted February 18, 2009 Share Posted February 18, 2009 Aviation Investigation Report, Stall and Loss of Control During Climb, Provincial Airlines Limited, de Havilland DHC-8-100 C-GZKH, St. John's, Newfoundland and Labrador, 27 May 2005 Link to comment Share on other sites More sharing options...
Bobcaygeon Posted February 18, 2009 Share Posted February 18, 2009 Aviation Investigation Report, Stall and Loss of Control During Climb, Provincial Airlines Limited, de Havilland DHC-8-100 C-GZKH, St. John's, Newfoundland and Labrador, 27 May 2005 The only similarity Don is the airplane. If you select "Vertical speed" in a cherokee or a jumbo jet and let it climb unmonitored eventually it will stall. "104kts in a Dash in any wx, icing or not, is a stupid place to be unless you just rotated or are in the flare. if addressed properly, a stall in the dash at 14K or 3K in KBUF should resemble that of a C172 or even better. This is not an RJ at FL410 Link to comment Share on other sites More sharing options...
Guest woxof Posted February 18, 2009 Share Posted February 18, 2009 Good link Don. Stall warning is of course based on a clean wing. Contamiate the wing and you may stall before the warning although I believe some will adjust the warning angle of attack threshold if de-icing equipment is activated. As your link shows....climbing on autopilot in vertical speed mode can lead to a stall as well if it is not monitored properly as a Mexicana DC-10 found out many years ago over Europe. After losing 10,000 feet because they stalled it, they airstarted #3 and continued on to the intended destination of Miami where it was discovered that 4 ft of each outboard elevator tip, including the corresponding counterweights and the aircraft's tail area lower access door were missing. http://74.125.95.132/search?q=cache:LYm2hp...lient=firefox-a Hey Capitain....maybe we should have turned back no? Link to comment Share on other sites More sharing options...
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