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Yesterday's IFR flight with questions
: For me, won't take a chance if there is known icing. Not worth it. Just
: like anything else we do, there is a risk of the unknown, but for me, if : there is ice reported I simply won't go. As someone else mentioned, icing airmets are present for large sections of the country for large portions of the year. Given the litigious society we're in and the unknown of icing, SCARE-MET zulu is issued if the conditions are possibly favorable for icing. It is sometimes possible to fly safely in such conditions if one knows what they're doing. It's also quite possible to be really stupid and/or ignorant about it and get into big trouble. Certainly nobody should fault you for a conservative attitude like that. If they are, they're an arrogant ass. Icing is nothing to mess around with for real. -Cory -- ************************************************** *********************** * Cory Papenfuss * * Electrical Engineering candidate Ph.D. graduate student * * Virginia Polytechnic Institute and State University * ************************************************** *********************** |
#2
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Yesterday's IFR flight with questions
On 18 Nov 2005 11:39:06 -0800, "Doug"
wrote: As for decending. if it is rime, I think 1500' of undercast is usually fairly safe. If it is freezing rain then no-go. Someone mentioned 1500' per minute. But the most important thing is keeping the airplane upright and not overspeed. You may want to use your standard decent rate and not go around doing something different. The word is that horizontal stablizer icing is the worst thing on decent. Don't use flaps for landing if you have ice when you land and land a little faster. Do everything at higher airspeed if you have ice. This will keep you above stall speed (hopefully). See that is the problem. Due to different shape of the wing due to ice the plane will stall at a higher airspeed. It is my understanding that ice forms less quickly when a propellor turns faster. If you want to descend quickly (low RPM) would the prop icing up and be a problem? As fo noticing ice, in the PA28 I fly, the first hint was on the left corner of the windshield (can't remember if it was top or bottom). There was also slight frosting on the temp probe. |
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Yesterday's IFR flight with questions
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#4
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Yesterday's IFR flight with questions
Doug wrote:
Was there an airmet for icing? I use this as a guide. If there is an airmet for icing, and I will be in IMC, I don't go. The airmets are a good guide. That and PIREPS. Where do you fly? You've probably heard this before, but in the Northeast US there seems to be a permanent AIRMET for icing over the region from November to April. If the presence of an AIRMET ZULU alone were used, many instrument pilots would lose their currency every winter. MEAs, ADDS icing forecasts, tops forecast or reports, temperatures aloft, location of the low pressure in relation to my route, and icing PIREPS are the criteria I use when weighing the icing risk. -- Peter ----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#5
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Yesterday's IFR flight with questions
A Lieberman wrote:
What a flight I experienced yesterday! Got to do more things I never did which made for such a wonderful learning experiences and also raised questions in my mind (surprise, surprise!). Allen, thanks for sharing your experience. I have about 1500 hours and I'm not sure how many of that are IFR, but still don't have much experience with ice. I attribute that more to luck than cleverness. Reading about others' experiences is priceless. The only added value I can provide is that I certainly wouldn't descend through potentially icy clouds at 500 fpm. I got the impression that's what you were suggesting, though I don't think you said it explicitly. You can safely come down at, say, 1500 fpm with practice and considerably reduce the amount of time of ice exposure. [Aside: my friend took me flying in Sundowner 1940L and those were the flights that piqued my interest in flying and got me started taking lessons. That plane must have been coming down the assembly line right in front of yours.] Dave |
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Yesterday's IFR flight with questions
Just a side note. "Evaporated on its own" is called sublimation. Defined as
any time a substance goes from solid to vapor without a liquid phase. The flip side is when water vapor becomes frost without an itermediate liquid phase. That's the virtue of getting on top; any ice accumulated on the way up will sublimate off over time...within reason. A trace of rime, a glaze of clear...sure. An inch of mixed ice? Don't bet on getting on top. Bob Gardner Bob Gardner "A Lieberman" wrote in message ... What a flight I experienced yesterday! Got to do more things I never did which made for such a wonderful learning experiences and also raised questions in my mind (surprise, surprise!). Really worked over my decision on to launch or not to launch today to fly from 2G2 (Steubenville, OH) to BWG (Bowling Green, KY) to MBO (Madison MS). Was closely watching the weather in Ohio, winds on the ground, winds aloft, clouds and ceilings, freezing level and everything else weather could throw a kink. Called FSS yesterday and this morning, no reports of icing, only airmets for moderate turbulence 10K and below. No TFRs in my route. Cloud tops were forecasted to be 6000. The further south I go, the better the conditions. Headwinds of 40 knots for the first leg, and tail winds of 15 knots for the second leg. The upper winds forecast were just about spot on. 2G2 is an uncontrolled airport. Weather was suppose to be IFR this morning, and I have never left an uncontrolled airport in IFR conditions. This of course required that I call FSS and get an ATC clearance. Every other time I have left an uncontrolled airport, I got my clearance in the air, but today, too much scud floating above my head. Temperature on departure was 43 degrees, with light sleet and rain falling. Figured the decision to leave was good, as somewhere above my head would be warmer weather then freezing temperatures due to the sleet falling. Also, based on radar trends, I knew I would be out of the precipitation within 10 miles. Question 1 at the bottom of this post regarding this situation. Got my ATC clearance from FSS and had to be off the ground in 13 minutes or my clearance was void. Not a problem, as I was the only one in the traffic pattern *smile*. Off I go, entering IMC at 2000 feet (900 feet AGL). I turn on my Pitot tube heat. Rain and sleet was falling, temperature held at 43 degrees entering the clouds. Break out on top at 5500. Final cruise altitude was 6000 (so I thought). Air was silk smooth! The further south I go, the clouds start to slope up hill, and I am more in IMC the further I go. Amazingly, the further south I go, the lower the temperature goes too. About 1 hour into my flight, center calls me and says, Sundowner 1943L, I have a reroute for you, are you ready to copy. I had filed direct, but I still am old fashioned by tuning each VOR in my path to help with my situational awareness. I replied standby, and grab my pen and erasable paper. Center says, you are now cleared direct to York VOR then direct to BWG due to MOA activities. Look on my maps, could not find YRK. Punched NRST on Garmin 296, and York was not listed. Sheepishly, I key up the mike and ask center for the frequency of York VOR. Center graciously gave me the frequency, and I dial it in and start tracking toward the VOR. Since I was in IMC, didn't want to mess around with the GPS, since it did not show on the list of nearest. What concerned me even more, was my DME was not reading a distance. I then called back into center and asked for the distance to the York VOR. They said I had 90 miles to go! Well crap, no wonder I couldn't locate it on the maps, I wasn't looking far enough down the road! This made me feel a little better, as I started wondering if I had lost situational awareness. I was then able to quickly find the YRK VOR on the en route map, and then decided to program my 2 GPS's for the YRK VOR for distance until my DME picked up the signal. I used my NAV1 and NAV2 for tracking, which really was fun to do, since I have not really tracked a VOR en route for some time . Get to the YRK VOR, turn direct to BWG. At this point, I am skimming the tops of the clouds more in then out. In a matter of 10 miles the temperature went from 35 to 25 degrees around this VOR. Watching my wings, see no ice, watching my windscreen, no beads of water or ice so I figured all was well (so I thought). I am still skimming the tops of the clouds, in visible moisture, but not your typical "hard" IMC. A few minutes later, I noticed that I had to sneak in a little more power then normal, which I thought was odd, so I decided lean a little forward to take a peek at the temperature probe. Sure enough there is a small coating of rime ice! I call into center and request to climb to 6,500 due to ice, and center quickly approved giving me a block altitude from 6000 to 7000. Center asked me to report when I climbed out of the clouds and to report when the icing has shedded. Cool I thought, I would stay 500 feet above the clouds and climb when needed. Turned out the clouds were reasonably level, so I was able to maintain level flight at 6,500. When the sun hit the wings, I could clearly see the ice on the leading edges as well as the leading edge of the stabilator. This really alarmed me as I could not see it while in "semi" IMC. I also was shocked how much accumulated in "semi IMC" as it was like wisps of clouds zinging by with some hard IMC interjected. I never really did shed the ice, it kinda evaporated on it's own, as the outside temperature was now down to 18 degrees. I reported to Center that I was out of the clouds and the ice was slowly disappearing. So now here I am on top, solid overcast and wondering just how safe will it be to descend through the cloud deck! (Question 3) Luckily, this never had to be answered as within 10 miles of BWG, the clouds broke up and I was cleared for a visual approach into BWG. I was monitoring any AWOS, ASOS and ATIS en route and found the closer to BWG I got the thinner the clouds got. Question 1 on Sleet. In my case, it was 43 on the ground, and on my climb to my altitude, the temperature remained well above 32 while I was in IMC. I climbed to 6000 which was my designated altitude. I broke out at 5,500. How far up can sleet be created and not melt before hitting the ground? There was a layer of clouds above me. Seems that from the ground to 6000 feet, I came across some hardy sleet pellets to survive that long in above freezing temperatures? Question 2 on icing. Had I not climbed up like I did, I would have never seen the ice on the wings or stabilator. I now know to look on that temperature probe for first signs of icing as I did today, but will it readily show up in IMC without reflections of the sun? Especially clear icing? Where else should I look besides the temperature probem? I have a white plane with blue strips in the wing tips, but I never saw the ice! It truly scared the bejeebers out of me to see the ice on the leading edges, and luckily, I am intimately aware of my plane and it's idiosycrosies that I knew that adding power was not a normal thing for straight and level flight. Question 3 on icing. knowing that flying into known icing is a big no no, (no kidding!). So, here I am on top, evaluating the cloud thickness, and finding that the clouds were generally 1,500 feet thick. Temperatures were dropping, which made me even more nervous about descending. Obviously every situation is different, but what would be a reasonable amount of time for descending into clouds that the temperature appears to be below freezing when the cloud deck is NOT thick. Figuring on 500 feet per minute descent, for me, 1500 feet is rather thick for 3 minutes. I would naturally descend quickly and as safely as possible, but is there a reasonable gauge for getting below a potentially THIN icy cloud deck? Clouds today were widespread all the way down to BWG. When I left, ceilings at BWG were 4200 which would have been a 1800 thick layer of clouds. As forecasted, the clouds broke up, but what if the forecast had busted? It's not like I could dip my wings to see if I get ice or not. Thanks for answering my questions! Allen |
#7
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Yesterday's IFR flight with questions
A Lieberman wrote:
I'm going to answer these before I read the other replies, to avoid prejudicing my own answers. Apologies for any duplication. Question 1 on Sleet. In my case, it was 43 on the ground, and on my climb to my altitude, the temperature remained well above 32 while I was in IMC. I climbed to 6000 which was my designated altitude. I broke out at 5,500. How far up can sleet be created and not melt before hitting the ground? There was a layer of clouds above me. Seems that from the ground to 6000 feet, I came across some hardy sleet pellets to survive that long in above freezing temperatures? I fly some IMC in winter here in central Canada and the NE US in my Warrior, and do occasionally encounter ice at altitude. Still, I would not take off if I saw sleet or ice pellets, period. I probably wouldn't even try it in a twin with boots, due to the risk of severe clear. Question 2 on icing. Had I not climbed up like I did, I would have never seen the ice on the wings or stabilator. I now know to look on that temperature probe for first signs of icing as I did today, but will it readily show up in IMC without reflections of the sun? Clear icing will show up easily on the probe, even at night, because it changes the shape of the tip. Rime icing, maybe less so. Figuring on 500 feet per minute descent, for me, 1500 feet is rather thick for 3 minutes. You might not want to descend that slowly through an icing layer. I don't think there's any reliable measure for how slowly or fast you can ice up -- I haven't had this happen to me, but I know people who've had the windscreen ice over almost instantly, as if someone threw a bucket of paint on it. You have to be prepared to land in a slip, looking out the storm window, if your defrost cannot clear it. If you're going to have to descend through a possible icing layer, set up everything in your favour beforehand: carb heat on, pitot heat on, defroster on, a big post-it note on your flap switch or handle saying "DON'T TOUCH" (flaps can cause a tail stall if you've encountered ice), and a fairly steep approach slope. Try to keep the throttle as far open as you can and don't slow down too much. Oh, did I mention? Don't touch the flaps. All the best, David |
#8
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Yesterday's IFR flight with questions
" wrote:
a big post-it note on your flap switch or handle saying "DON'T TOUCH" (flaps can cause a tail stall if you've encountered ice), Is that true in a low wing? -- Peter |
#9
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Yesterday's IFR flight with questions
Peter R. wrote: " wrote: a big post-it note on your flap switch or handle saying "DON'T TOUCH" (flaps can cause a tail stall if you've encountered ice), Is that true in a low wing? I don't remember the NASA icing video making a distinction. Are you thinking of the Cessna slips-with-flaps permathread? I think that's unrelated. All the best, David |
#10
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Yesterday's IFR flight with questions
" wrote:
I don't remember the NASA icing video making a distinction. Are you thinking of the Cessna slips-with-flaps permathread? snip No. I can visualize how flaps will disturb airflow over the horizontal stabilizer of high wing aircraft, but I am having difficulty visualizing how airflow over the horizontal stabilizer of a low wing is disturbed by the lowering of flaps. I should point out that I went from a high wing to a V-tail Bonanza after my instrument rating, so I have no straight-tail low wing time. -- Peter |
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