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#1
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Severe (or more) turbulence... how common?
Flying from Palo Alto to Santa Monica yesterday, we hit (I think) a rotor
coming over the mountains north of LA. We'd had some fairly strong up and downdrafts, though nothing really unpleasant, when suddenly we were going DOWN - about 2000' in 10 seconds or so, everything stuck to the roof for maybe 5-10 seconds. It was an interesting ride... most things landed shortly afterwards (and I even found a flashlight that had disappeared) although my E6B remained lodged somewhere and fell on my head on final. Afterwards, my wife asked me how often this happens... once per flying lifetime, much less, every few years. I couldn't answer... for sure the first time in my 600 hours, but that's not much. So here's my informal sample... how many people here have had a similar experience? Anyone care to guess how unlikely this it? (And to forestall, or try to, the people who tell me I should know something about mountain flying, yes I HAVE read Sparky Iverson's book, and anyway living in the Bay Area it's hard to go anywhere much without overflying mountains. I was over 2000' above terrain too, 9500' over a ridgeline at about 6000'). John |
#2
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Could be? What were the winds at, when you were flying over the mountains
(I assume you were actually flying through the pass?) ? One day, early in my primary training (way back when I was still at the 'evil' FBO grin, my instructor and I, were flying out along the coast, headed to Half Moon Bay Airport to practice some t/o & landings at another airport. Just as we were passing over the water (with the plan of flying along the coastline with highway one on our right) without any warning the plane just 'dropped' in the manner you described. The funny part about the whole thing is that my instructor had, moments earlier in the flight, been explaining how there is smooth laminar flow over the ocean. I really wasn't scared (I was probably at my 9th or 10th hour by then) when it happened, mainly because my instructor took it right in stride. I do remember he called in a PIREP for CAT (clear air turbulence) as he told me that it should be something that some other pilots be made aware of. By the way, have you seen the Sparky I's video on mountain flying - some great footage and visual instruction aids - since you mentioned the book. -- -- =----- Good Flights! Cecil PP-ASEL Check out my personal flying adventures complete with pictures and text at: www.bayareapilot.com "I fly because it releases my mind from the tyranny of petty things." - Antoine de Saint-Exupery - "We who fly, do so for the love of flying. We are alive in the air with this miracle that lies in our hands and beneath our feet" - Cecil Day Lewis - "John Harper" wrote in message news:1075704296.323452@sj-nntpcache-5... Flying from Palo Alto to Santa Monica yesterday, we hit (I think) a rotor coming over the mountains north of LA. We'd had some fairly strong up and downdrafts, though nothing really unpleasant, when suddenly we were going DOWN - about 2000' in 10 seconds or so, everything stuck to the roof for maybe 5-10 seconds. It was an interesting ride... most things landed shortly afterwards (and I even found a flashlight that had disappeared) although my E6B remained lodged somewhere and fell on my head on final. Afterwards, my wife asked me how often this happens... once per flying lifetime, much less, every few years. I couldn't answer... for sure the first time in my 600 hours, but that's not much. So here's my informal sample... how many people here have had a similar experience? Anyone care to guess how unlikely this it? (And to forestall, or try to, the people who tell me I should know something about mountain flying, yes I HAVE read Sparky Iverson's book, and anyway living in the Bay Area it's hard to go anywhere much without overflying mountains. I was over 2000' above terrain too, 9500' over a ridgeline at about 6000'). John |
#3
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"John Harper" wrote in message Flying from Palo Alto to Santa Monica yesterday, we hit (I think) a rotor John..... IIRC, the standard for severe turbulence includes near total inability to control the aircraft while in its effect. For me, that happened once in 26 years. Regards, John Gaquin B727, B747 |
#4
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Are you sure about those figures? If the acceleration was constant. 2000'
in 10 seconds is a vertical speed of zero increasing to 24,000fpm (270mph+) in five seconds and then back to zero in another five seconds. I have never heard of anything like it and certainly never experienced anything similiar. I have experienced vertical speeds of 5000fpm in mountan waves systems on the east side of the Sierra near Minden, but those were with 100kt+ winds at ridge level (trees knocked down, semis turned over, planes beaking tie down ropes ect) Mike MU-2 "John Harper" wrote in message news:1075704296.323452@sj-nntpcache-5... Flying from Palo Alto to Santa Monica yesterday, we hit (I think) a rotor coming over the mountains north of LA. We'd had some fairly strong up and downdrafts, though nothing really unpleasant, when suddenly we were going DOWN - about 2000' in 10 seconds or so, everything stuck to the roof for maybe 5-10 seconds. It was an interesting ride... most things landed shortly afterwards (and I even found a flashlight that had disappeared) although my E6B remained lodged somewhere and fell on my head on final. Afterwards, my wife asked me how often this happens... once per flying lifetime, much less, every few years. I couldn't answer... for sure the first time in my 600 hours, but that's not much. So here's my informal sample... how many people here have had a similar experience? Anyone care to guess how unlikely this it? (And to forestall, or try to, the people who tell me I should know something about mountain flying, yes I HAVE read Sparky Iverson's book, and anyway living in the Bay Area it's hard to go anywhere much without overflying mountains. I was over 2000' above terrain too, 9500' over a ridgeline at about 6000'). John |
#5
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Yes, that's pretty much what my math came up with too. But for sure
I lost 2000' (I couldn't believe it when I looked at the altimeter after recovering the plane - I'd been pretty focussed on the ASI since I was close to redline). And I don't think the whole thing lasted more than 10 seconds, although of course I wasn't timing it. Maybe it was longer, but usually these things seem to last longer than they really do, not less. The terrain there is a bit special - there's a first ridgeline which is at 6000-7500', then after a couple of miles there's a lower ridge at around 4000', with a valley in between at about 2000'. I think the only reason I recovered (much though I'd like to take credit for my excellent airmanship :-) ) is that we flew through the downdraft. I don't know whether this was "severe turbulence" according to the definition. It was actually quite smooth, except that we were going down at something around -1G. I did keep the plane under control - my main concern being to avoid hitting Vne. We came out about 30 degrees off heading. My wife says we did bank quite steeply - she was looking out of the windshield, I was focussed on the instruments. Whether it was "severe" or not, it was certainly quite an experience, one I'm not in a big hurry to repeat. John "Mike Rapoport" wrote in message ink.net... Are you sure about those figures? If the acceleration was constant. 2000' in 10 seconds is a vertical speed of zero increasing to 24,000fpm (270mph+) in five seconds and then back to zero in another five seconds. I have never heard of anything like it and certainly never experienced anything similiar. I have experienced vertical speeds of 5000fpm in mountan waves systems on the east side of the Sierra near Minden, but those were with 100kt+ winds at ridge level (trees knocked down, semis turned over, planes beaking tie down ropes ect) Mike MU-2 "John Harper" wrote in message news:1075704296.323452@sj-nntpcache-5... Flying from Palo Alto to Santa Monica yesterday, we hit (I think) a rotor coming over the mountains north of LA. We'd had some fairly strong up and downdrafts, though nothing really unpleasant, when suddenly we were going DOWN - about 2000' in 10 seconds or so, everything stuck to the roof for maybe 5-10 seconds. It was an interesting ride... most things landed shortly afterwards (and I even found a flashlight that had disappeared) although my E6B remained lodged somewhere and fell on my head on final. Afterwards, my wife asked me how often this happens... once per flying lifetime, much less, every few years. I couldn't answer... for sure the first time in my 600 hours, but that's not much. So here's my informal sample... how many people here have had a similar experience? Anyone care to guess how unlikely this it? (And to forestall, or try to, the people who tell me I should know something about mountain flying, yes I HAVE read Sparky Iverson's book, and anyway living in the Bay Area it's hard to go anywhere much without overflying mountains. I was over 2000' above terrain too, 9500' over a ridgeline at about 6000'). John |
#6
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But for sure I lost 2000' (I couldn't believe it when I looked at the altimeter after recovering the plane... [...] I don't know whether this was "severe turbulence" according to the definition. [...] I did keep the plane under control - my main concern being to avoid hitting Vne. Unless you intended to lose 2000 feet, I'd say the plane was not under control. The wings may have been level, but two thousand uncommanded feet of altitude loss qualifies to me as severe turbulence. And whether it was smooth or not is irrelevant - bumpy air is "chop", altitude deviations are "turbulence". Sort of. Jose -- (for Email, make the obvious changes in my address) |
#7
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"John Harper" wrote in message news:1075704296.323452@sj-nntpcache-5...
So here's my informal sample... how many people here have had a similar experience? Anyone care to guess how unlikely this it? I've had it twice in 15 yrs. (about 1900 flying hrs.). The first was on my student dual X-C. It was windy, but we weren't flying over any mountains or ridges. It was one big jolt and that was it. My instructor had just undone his shoulder harness to retrieve something from the back seat. His head slammed into the ceiling and was a little disoriented for a few minutes. Both my hands and feet left the controls when it hit. I had an interesting bruise from the shoulder harness and on my shins where they hit the bottom of the panel. The second was coming out of a pass in the Alaska Range on the leeward side. Winds aloft at the peaks were in the 40 Kt range and there were standing lenticulars all over the place. I flew into a rotor right about where it should have been. Not very smart and I should have known better. The plane was uncontrollable in pitch and roll for about 15 seconds. John Galban=====N4BQ (PA28-180) |
#8
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Well, I was about to start descending, and it was quite handy to lose
2000', but I certainly wasn't planning to lose it THAT quickly! In any case I reported it as severe turbulence at the time. I forgot to mention that I had a 25kt tailwind - nothing remarkable - at 9500'. It sped up to 40kt or so over the ridge, I was briefly showing ground speed over 200kt. John "Teacherjh" wrote in message ... But for sure I lost 2000' (I couldn't believe it when I looked at the altimeter after recovering the plane... [...] I don't know whether this was "severe turbulence" according to the definition. [...] I did keep the plane under control - my main concern being to avoid hitting Vne. Unless you intended to lose 2000 feet, I'd say the plane was not under control. The wings may have been level, but two thousand uncommanded feet of altitude loss qualifies to me as severe turbulence. And whether it was smooth or not is irrelevant - bumpy air is "chop", altitude deviations are "turbulence". Sort of. Jose -- (for Email, make the obvious changes in my address) |
#9
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I flew from vegas to Ontario (in the LA basin) last wednesday, comming over the
mountains (ziggy 3 arrival) we had a 1000 FPM downdraft and on the approach to ONT it was horrible. I couldnt stay on the ILS for nothing. We was bouncing all over the place. The downdraft was not a problem because I had to decend from 12000 to 9200 anyways, but I did have to lead leveling off by about 500 ft. I fly into the LA area all the time and that had to be the worst day so far. But it was to be expected with the storms moving in and out. John Harper wrote: Flying from Palo Alto to Santa Monica yesterday, we hit (I think) a rotor coming over the mountains north of LA. We'd had some fairly strong up and downdrafts, though nothing really unpleasant, when suddenly we were going DOWN - about 2000' in 10 seconds or so, everything stuck to the roof for maybe 5-10 seconds. It was an interesting ride... most things landed shortly afterwards (and I even found a flashlight that had disappeared) although my E6B remained lodged somewhere and fell on my head on final. Afterwards, my wife asked me how often this happens... once per flying lifetime, much less, every few years. I couldn't answer... for sure the first time in my 600 hours, but that's not much. So here's my informal sample... how many people here have had a similar experience? Anyone care to guess how unlikely this it? (And to forestall, or try to, the people who tell me I should know something about mountain flying, yes I HAVE read Sparky Iverson's book, and anyway living in the Bay Area it's hard to go anywhere much without overflying mountains. I was over 2000' above terrain too, 9500' over a ridgeline at about 6000'). John |
#10
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Smooth air does not consitute turbulence, nor does an altitude
excursion in smooth air. Mountain wave often causes uncommanded altitude excursions of substantial magnitude but the air is absolutely smooth. That is not turbulence. The airplane is under control, it is just in an air mass that is rising or descending faster than the airplane has the performance to overcome. In general turbulence is defined as the force you feel as you are thrown against the seat belt. So, it isn't even light until you are being tossed against the belt. Severe is where control of the airplane is in doubt and there may well be some question as to whether the airplane will hold together. It is truly no fun at all when you get into a condition where you cannot cause the airplane to return to wings level flight due to the frequency and violence of the displacements that are occurring. You also may face the risk of being rendered unconscious due to striking the ceiling of the cabin. Fortunately, it is rare. If I recall correctly, a severe turbulence encounter in a transport category aircraft requires a full airframe inspection. It's a good idea in an FAR 23/CAR 3 airplane as well as a good friend bent the wings of his Meridian last summer while avoiding thunderstorms when he encountered severe turbulence. All the best, Rick (Teacherjh) wrote in message ... But for sure I lost 2000' (I couldn't believe it when I looked at the altimeter after recovering the plane... [...] I don't know whether this was "severe turbulence" according to the definition. [...] I did keep the plane under control - my main concern being to avoid hitting Vne. Unless you intended to lose 2000 feet, I'd say the plane was not under control. The wings may have been level, but two thousand uncommanded feet of altitude loss qualifies to me as severe turbulence. And whether it was smooth or not is irrelevant - bumpy air is "chop", altitude deviations are "turbulence". Sort of. Jose |
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