Paul Soderlind didn't invent smooth air, but he can tell you where to find it. Northwest Airlines still uses the "Turbulence Plot" system he developed as Director of Flight Operations there. Pilots who use his critical-airspeed "Bug System" find it easy to transition from one type to another. Paul has spent his life studying, improving and simplifying how to fly. In this month's Profile AVweb's Joe Godfrey interviews Paul about his many accomplishments.
|Check out AVweb's "Airmanship" section, where Paul offers an article about deadly spirals that could save your life.|
Paul A. Soderlind was born August 6, 1923, in Billings, Mont. He took his first flight lesson at age 12, earned his private certificate on his 18th birthday (which was then the CAA minimum age), and earned his Commercial and Instructor ratings three months later. In 1942 he was hired by Northwest Airlines to teach instrument flying to new pilots. In 1944 he took two years of military leave from Northwest to become an instructor and check pilot for the Naval Air Transport Squadron. When the war ended he went back to Northwest, but at age 22 was still several months too young to hold the Air Transport Rating. On his 23rd birthday he checked out and became the nation's youngest airline captain. Many of the standards and procedures he developed as a line pilot were adopted by the airline, and in 1954 Paul was named Northwest's Director, Flight Operations-Technical. In that job he flew all the types Northwest operated from the Boeing 247D up to and including the Boeing 747. He also flew the acceptance test and delivery flights on Northwest types from the Douglas DC-6B up through the 747. In his 30,000+ hours he has flown some 350 types of airplanes, helicopters and gliders, about 25 different types of airliners, about 20 bizjet and turboprops, and some 50 different GA types, including Molt Taylor's Aerocar.
He retired from Northwest in 1973, and has given lectures at ICAO, IATA, Boeing, NBAA, ALPA, IAA, Embry-Riddle, the U.S. Air Force, and the FAA Academy. He has served as a consultant to FAA Administrators Alexander Butterfield, Langhorne Bond and David Hinson, Associate Administrator Richard Skully, and (sadly for us) turned down an offer from the Reagan administration to head the FAA. His list of bizjet consulting jobs reads like the Fortune 500, and his list of airline consulting jobs reads like the Dow Jones Transportation Index. He has flown over most of the Northern Hemisphere (and some of the Southern), from Hong Kong on the west to Paris on the east, including the Philippines, Taiwan, Japan, Alaska, Canada, Hawaii, and most of the contiguous United States. These days he's working closer to home implementing The Bug System and other procedures and systems for Corporate Air in Billings. He has won bookcases full of awards, including the 1964 ALPA Air Safety Award, the first FAA Citation and Gold Medal for Extraordinary Service to Aviation Safety, the 1979 Laura Taber Barbour Air Safety Award, the 1985 General Billy Mitchell Award, a 1994 FAA Special Recognition Award for Lifelong Commitment to Aviation Safety, and in 1997 was inducted into the Minnesota Aviation Hall of Fame. In 1999, Aviation Week and Space Technology honored Paul and his partner, Northwest's Chief Meteorologist Dan Sowa, for the Turbulence Plot program they developed in 1965.
How did your life in aviation begin?
I don't remember this but when I was about one year old my folks moved from Billings out to a little town called Rapelje, which was about half as big as a city block. Jumping ahead, when I was doing the acceptance and delivery test for the 747s for Northwest and I'd do a gentle buzz job over Rapelje I remember commenting that I never thought I'd fly an airplane bigger than my hometown. I don't remember this either but my mother did and she's usually right. She said that when I was about two years old I used to poke at the flies on the window and say "airplane." We lived in Rapelje for eleven years, and when I was twelve we moved to Billings and I moved to the airport. Literally. I wouldn't come home at night if I could sleep in an airplane or a hangar. My folks got used to that and it kept me out of their hair.
I worked as a flunky. The fancy term for it now is "lineboy." I was a general pest to everybody and bugged people to wash their airplanes and get some flight instruction. I graduated slowly from washing airplanes to pushing them in and out of the hangars. I got paid $3.50 a week and they said I was worth it. The flight service— today we'd call it an FBO— was a one-man operation and I would pester this fellow into giving me some of the flight instruction that I had earned. So it took me from May of 1939 to December of that year to get enough time to solo. I also worked as an apprentice mechanic. I'd do just about anything around the airport to get some flying time.
What airplanes were you flying?
I couldn't pick and choose. I had to take what was available. One was an E-2 Cub, which was the Taylor Cub, before the Piper Cub. C. G. Taylor owned Taylor Aircraft and sold it to Piper. It had a 37-horsepower engine. Like the J-3 Cub, it had a little crank to move the stabilizer. On the E-2, there was no crank. It was clothesline rope that ran through two pulleys and back to the jackscrew on the stabilizer. It took two hands to move it because you had to pull on one rope and push on the other, so you had to let go of the stick.
Here's a weird story but I swear every syllable of it is true. Let me leap ahead to the early jet airliner days. There were several airplanes lost, and unfortunately Northwest was the first, to lose an airplane to something called the Jet Upset Phenomenon. In those days no one knew much about Mach number and compressibility and shock stall and mach buffet. I was deeply involved in the investigation of the Jet Upset Phenomenon because the first airplane was a Northwest 720B in the Florida Everglades. The 720B was really nothing more than a 707 with a different name. They went straight into the ground from about 20,000 feet. The airplane was found with the stabilizer trim in the extreme airplane nose-down position.
In the 707/720 series airplanes you were able to split the spoilers extending only the inboards or outboards. You used the emergency spoiler switches to do this, and you learned the rule "inboards UP" (turn the inboards OFF), then when you pulled the spoiler handle back you extended only the outboards. With the jet's wing swept back, the outboard spoilers were aft of the inboards and if you extended the outboards only it "spoiled" lift aft due to the extended spoilers and preserved lift forward since with the inboards turned OFF they did not extend thereby causing a nicely controlled nose up pitching moment. While Northwest had the first known jet upset crash it was followed almost immediately by several others in the airline industry, the military and bizjet operations. We did a great deal of flight and simulator testing both in conjunction with Boeing and many "on Northwest's own." In the process we sorted this all out and I became somewhat of a — you'll pardon the expression — "expert" on phenomenon, its cause and how to recover from same.
Jet transports have a trimmable stabilizer, the aerodynamic function being the same as in Taylor and Piper Cubs. If you trim nose down but counter any pitch change with up elevator, opposing air loads on the stabilizer jack screw jam the stabilizer so you can't move it. The classic jet upset begins with the airplane pitching up upon entering a gust — the term "gust" is not technically correct but use of the term here usually makes the phenomena easier to understand — to what pilots who lived through the phenomenon said was "the vertical." While the pitch-ups seldom if ever really went all the way to the vertical, 30+ degrees nose-up in an airliner can look like vertical. The pilot would try to counter the pitch-up with down elevator, and when this didn't stop it the pilot would intuitively begin trimming the stabilizer AND (Airplane Nose Down).
When the "gust" reverses itself the airplane pitches violently nose down under the influence of, by then, full down elevator and full AND stabilizer. To counter the developing steep nose-down attitude and rapidly increasing speed, the pilot applies up-elevator which, with the stabilizer still full AND is not enough to get the nose-up without the greater aerodynamic force stabilizer trim provides. The pilot tries to trim ANU but finds the stabilizer jammed just like I discovered in the E-2 Taylor Cub in 1938, 68 years ago! A weird story but absolutely true, syllable by syllable! Airspeeds in the dive can go well beyond the Barber Pole, the jet's "red line" airspeed limit, and rates of descent can exceed 50,000 FPM. The stabilizer trim can be "un-jammed" only by momentary release of elevator back pressure, hard to do when diving toward Mother Earth at such speeds, but this "cure" is guaranteed assuming the stabilizer drive system is otherwise normal.
With what I had learned in investigation of the upset cases I developed a six-hour lecture for Northwest pilots. The FAA made the lecture mandatory for all U.S. carriers and it was followed by similar action with the foreign carriers. Having been the only one fortunate to learn these things at first hand, I was the one to give the foreign carriers the lecture myself; it helped that there were nowhere near as many then. And they made it convenient by assembling all together at an ICAO conference in Montreal in 1964.
I hope I am not going too deep with this but it all was a very productive and exciting interlude in my career.
Not too deep at all. If I can follow it anybody can. Sounds quite relevant to today's turbine pilots.
It is unfortunate that how and why the classic jet upset occurs, what to do when it does, stabilizer drive stall and how to "cure" it, and other related factors we learned the hard way — "on the job" yet they are not being passed on to today's airline and other pilots. I have done my own private, unscientific survey and have yet to find a single airline that teaches these things. It's even more important today because of the greater number of flights, often lower level of pilot experience and the explosive rate of growth airlines are experiencing.
I am utterly convinced this sad state of affairs is due to the NIH (Not Invented Here) syndrome. I have seen it at work over and over for years. In one case, I made a presentation on The Bug System (TBS) to another carrier. They operated several fleet types and with TBS could fly them all with the same simple procedures. TBS has saved Northwest "tons of money" in training costs alone, not counting the obvious reduced costs related to the improved safety they've enjoyed over the 40 years they've used the system.
Several years ago the Vice President of another airline asked that I make a presentation on TBS to his management pilots, including his instructor and check pilot groups. I had to travel 1,000 miles to do this but that was no real problem since it was for the good of his operation. At "show time" they had to find a larger room to accommodate the standing room only audience. My "speech" went very well and was received graciously. The whole process took $1,000 from my own pocket. To this day I have never heard a word of either acknowledgment or appreciation from that airline.
It is not the first time I've had such a disappointing experience.
That airline — and several others — still plod along today flying their airplanes with a different system for each type in the fleet. Somehow this evokes memories of my wonderful, now-departed mother-in-law (who did not look kindly upon drinkers) who poured the dregs of several different wine bottles into one "to save space." One can imagine how pleasant the taste of that mixture. But with procedures, it's much worse.
What has been said here about TBS is all the more true of Northwest's Turbulence Plot (TP) system. It has given Northwest the best turbulence avoidance system of all U.S. carriers, a fact that has been well documented. Two of the most highly respected pilots in the industry — your own John Deakin, a JAL 747 Captain, and TWA's retired Chief Pilot Bob Buck known world- wide for his down-to-earth, ham and egg language on how-to-fly and related weather books, not to mention his deliberate thunderstorm and icing penetrations as safety-advancing research — call the TP program respectively "a program that is admired worldwide" and "(giving Northwest) the most enviable safety record as to turbulence in the industry." Painstaking, careful calculations — not wild guesswork — shows Northwest saves some $700,000 a year, more than $22 million in the 32 years since the system was developed. Well-documented cases demonstrate how, where and why others experienced fatal accidents while transgressing Northwest TP "do not fly" areas. I am astonished other carriers cannot see the obvious competitive advantages the program gives Northwest.
One should note that I no longer have any connection with Northwest except for a fierce loyalty to my alma mater who gave me opportunities I would never have enjoyed otherwise.
I expect much of the above will be called "sour grapes" by some, even make a few enemies. But it has badly needed saying for too long and no one else has been as intimately involved in both programs; any blame can be put on me.
One last, probably unpalatable-to-some comment: The very worst thing that could be done is to expect either the NTSB to recommend the FAA make the systems mandatory, or the FAA to do it "on their own" for that would simply be a disaster! It would only make operators dig their heels in against it more deeply. If an operator cannot see the obvious benefits, safety and economy, in either program, being forced to adopt them would be a fiasco.
You may draw your own conclusions about NIH. Sigh!
Let's return to earlier days. When did you get your private certificate?
I got my private license on my 18th birthday and got my instructor's rating shortly after that. War was building up and for a few months I instructed in Billings in the Civilian Pilot Training Program. The army would contract with local flying services to give them their private licenses and some aerobatics and instrument training. Then I went to a flying service in Spokane, and instructed until about July of 1942. I wanted to go with an airline and Northwest was interested but I had to get my instrument rating before they would hire me. So I went to Chicago to a little airport which was long ago swallowed up by O'Hare and did that.
How big was Northwest in those days?
They were desperate for pilots because they had just gotten a pretty large contract to fly cargo and army personnel into Canada, Alaska and the Aleutians. Pilots weren't able to get their own instrument ratings fast enough so Northwest set up their own instrument school in Rochester, Minnesota. I instructed there for a few months and then signed on as a co-pilot and flew the AlCan route for a while before I went to the mainline. That was a great education because it was all ice and instruments in Canada and Alaska and you learned in a hurry.
Before the army contract Northwest had seven DC-3s. Here's an interesting sidelight. When Northwest got the first 747s those low-profile tugs that we used to move them each weighed 125,000 pounds and cost a dollar per pound. That was the cost of a DC-3 in 1940.
How reliable was the instrument flying you were doing?
All we had then for enroute instrument guidance was the low-frequency radio range and the ADF. If we had one in an airplane now and you could go out and fly with it you would think "Well, these guys were crazy." And we were.
How reliable were the flight instruments?
Actually they were surprisingly reliable. All we had the was the turn and bank and airspeed indicator, thus the term "needle ball and airspeed" as the system was called. But it wasn't long before the artificial horizon and directional gyro came along and a handful of ILS systems were sprouting at larger airports such as Seattle, Minneapolis, Chicago, etc. These were a godsend for instrument approaches to low weather minimums. The LF range was all audio and you followed the solid tone that made up course that pointed to where you wanted to go. Each LF range had four legs two of which pointed each toward the next closest LF range. The range had four quadrants, two with an "A" signal (dit dah) and two with an "N" signal (dah dit) and where they overlapped in a solid tone defined on course. Your instrument instructor would get you lost somewhere between the four legs and you had to do an "orientation problem" to find which of the four quadrants you were in; only then could you pick the leg you wanted to travel along.
The "orientation problems" were odd and complicated. You had no idea where you were except that you were in either an "A" or an "N" quadrant. To find out which of the four it was you used one of two basic procedures: the "fade parallel" or the "fade perpendicular." You took up a heading parallel to the quadrant bisector line and of course didn't know whether you were headed toward or away from the station. You clamped the earphones down tightly and listened for a fade or increase in volume (thus the term "fade parallel"). If the signal faded out you were going away from the station and you would turn 180 degrees and listen carefully for the increase that would confirm you were now heading toward the station. When you got over the signal would fade to zero and you were over "the code of silence" and turned to whichever of the legs pointed to where you wanted to go.
How did WWII change your career path?
In July of 1944, in a fit of patriotism that was brought on by the draft board getting close, I went into the navy. The navy was short of pilots and I had a fair amount of experience in DC-3s and C-46s so they made me a squadron instructor and check pilot in Naval Air Transport Squadron (NATS) VR-3. Here's another coincidence. While in the navy at Corpus Christi I married a Minnesota girl on July 3rd, 1944, not knowing at the time that we had both gone to work for Northwest the same day two years earlier. We were married shortly before I made captain and she rode with me on my airline captain rating ride on my 23rd birthday. While checking out on one's birthday may have been a first, her ride with me on the rating flight must surely be a real first. We're still happily married 57 years later!
When the war ended and I went back to the airline I was still too young — probably too immature — to meet the airline captain minimum age of 23. It turned out to be a great opportunity since as the senior co-pilot I could choose the captains I would fly with. I chose those that were known as excellent instructors and again: what an education! I remember one Captain I flew with who told me I wasn't holding altitude so good on instruments. I was holding it within about ten feet and I thought I was doing okay, but he said I would have to shape up on my altitudes. I had been with him long enough that I could talk back a little bit and I said "You'd bitch if you were hung with a new nylon rope!'
After serving as a Captain on the DC-3, the DC-4, the DC-7, the Boeing Stratocruiser and the Martin 202, in 1954 I was given the position of Director of Flight Operations-Technical. A better title would have been Technical Chief Pilot, but I was in charge of writing procedures and teaching pilots how to fly big airplanes. I had a lot of authority because I just took it. I didn't ask the boss if I could take an airplane out and mess with it.
What did you do in that job?
It was my job to manage the technical (how to fly) side of the Northwest operation. I developed standardized checklists and procedures for the various types Northwest flew, and determined what kind of instruments and how they were arranged. One of the most pleasant responsibilities was the acceptance tests and delivery of each new type Northwest acquired. The airplane was mine until I was satisfied at the factory that every gizmo operated perfectly. The delivery flight to our Minneapolis headquarters was without passengers and I had the freedom to run any tests and experiments I thought necessary. These included probing — in a cowardly manner — of mountain wave and other Clear Air Turbulence [CAT] as well as thunderstorms. There was no other way to gain a full a truly full understanding of the weather phenomena an airline pilot faces day in and day out. The experience allowed me to write practical "how-to-fly" procedures with the background to do so while gaining the confidence of the line pilots.
I instructed in every airplane that Northwest had. As the acceptance pilot, I didn't have a type rating. You'd get that by flying the airplane first, then you'd give type ratings to the other pilots. I did the initial instruction on each of the new airplanes that Northwest bought from the DC-6 up through the 747.
How did the Turbulence Plot system get started?
Dan Sowa, Northwest's Chief Meteorologist, and I recognized the government weather services were badly behind the times, especially concerning timely dissemination of severe weather information on thunderstorms, for example. We convinced Donald Nyrop [then president of Northwest] to let us obtain direct connection to both the civil and military ground weather radars. In this way we could bypass the typical one-hour-plus delay in getting the information to our pilots. There is much more to the story but in a nutshell the Turbulence Plot system that we developed allowed Northwest to get severe weather data into the cockpit of any Northwest flight anywhere in the world in as little as eight minutes form when a storm was aborning on the ground weather radars. The system was put into use in 1968 and since that time Northwest has had the best turbulence avoidance record of any operator. With a "picture" of the storm or CAT area in their hands Northwest flights were able to detour severe weather in the immediate area of where other operators suffered fatal accidents.
Do the plots plot more than active thunderstorm cells?
While thunderstorms are number one, the T.P. system covers mountain wave and other Clear Air Turbulence, low-level wind shear, microburst areas, icing areas and on the rare occasions it is required, areas of ozone and volcanic ash concentrations. Ozone is a hazard to passengers and crew and volcanic ash is a serious hazard to the engines and airframe.
When did you retire from Northwest?
In 1973 the doctors diagnosed a mild case of atrial fibrillation which has proven nothing more than an occasional annoyance. Mild annoyance in this case stopping my airline career of 32 years! I wasn't quite 50 years old but because of the terrific education of my Northwest position, both as line pilot and Director of Flight Operations - Technical, I have a relatively good reputation in the industry. Not knowing what in Heaven's name I was going to at such a tender age, I went to the small Montana ranch— 200 acres, by Montana standards just a very small lot— we had bought circa 1972 to brood about my future. Strangely enough I began to get calls. The first call offered me the job of Flight Operations VP for National airlines, now defunct. I passed that up as I would be a miserable failure in any kind of administrative position. But the calls have kept coming at more or less regular intervals.
Perhaps the weirdest assignment was serving at the request of General Public Utilities in investigation of the Three Mile Island nuclear accident. I have also served as an expert witness for Boeing's law firm and several others, again wonderful educational opportunities. During the Reagan administration I was asked to be the FAA Administrator but — thankfully — my better judgment got the edge over my ego and I turned it down. No place for a practical, technically-oriented, no-red-tape kind of guy.
One morning when I was still in bed I got a call from Langhorne Bond, then the FAA Administrator. When I answered the phone and heard who was calling, I not only stood up but stood up at attention! He had just grounded the DC-10s and asked that I meet him at Douglas in Long Beach at 1000 the next morning to work as his adviser in the investigation. On hearing that I had a 75-mile drive just to bet to Billings and couldn't get an airline flight in time to meet his 1000 goal in LAB he said "Yes you can; I have Sabreliner on the way to pick you up!" Wow! My own personal executive jet!
During certification of the MD-80 (originally called the DC-9-80) ALPA raised a fuss about FAA's intent to certify the airplane with a two-man crew. Bond called again: Would I conduct an independent flight test program in the yet-uncertified MD-80 and give him my opinion on the two-man vs. three-man crew matter. I agreed on the basis I could run a thorough flight evaluation with simulated engine failures, instrument system failures, operation in congested areas, a full workout. He gave his complete blessing to that and I spent a valuable education two weeks of flying a brand-new MD-80! And get paid for it! When it was all over I gave him my opinion the a two-man crew was entirely adequate. The MD-80 was much more highly automated than prior DC-9s and had better flight characteristics, it was much easier to fly.
Who are you tailoring The Bug System for?
Some of my present and recent-past clients are General Mills Flight Department, Cargill FD, Owens Illinois FD, H..S. Zachary Company FD, Minnesota Mining and Manufacturing (3M), Qantas Airlines of Australia, several FAA Administrators, and Southwest Airlines.
Perhaps most of the calls have been from executive airplane turboprop and jet operators to tailor The Bug System to their fleets, T.S. being a simple system that optimizes performance, essentially eliminates the need for memory, and is virtually identical for the Cessna 152 and the 747. Learn it on one type and what has been learned is directly transferable to other types, no matter how large or complex.
Any chance of getting some of your wisdom in a book, or maybe some AVweb articles?
Of course. I like to write and given the wonderful and unique opportunities to learn I've had I truly want to pass on some of the practical stuff I've learned. I want to write a book but seem to have too little time. I recently wrote an article on "The Deadly Spiral" that explains the cause and simple one-step "cure" of the often fatal spiral dive. Too few pilots understand an airplane's spiral mode and virtually all conventional— and most unconventional— airplanes are spirally unstable.
There are dozens, maybe hundreds, of myths about how to fly and/or why an airplane does what it does and these need to be exploded. My good friend John Deakin is probably the greatest exploder of such myths, at least up to now. Just kidding John.
To mention a few such myths (Deakin calls them OWTs, Old Wives Tales): Airplanes do not stall at a single of attack; you can't see where you're going in a "maximum gradient" climb; the conventional procedure on how to recover from the deadly spiral has steps that are detrimental and some dead wrong; in the GA airplane partial flaps should be used for all — or most — takeoffs; the everyday landing will be shorter with full rather than approach flaps. And a shocker to most pilots: absent an inertially driven attitude system or its equivalent you have never had accurate attitude indications and will continue on that sorry path. And on and in ad infinitum. I want to explode them all.
What should the average pilot know about wind shear?
Everything, of course! But I'll try and pack some practical advice in the smallest nutshell I can devise.
In an INS-equipped airplane — like the 747s I flew across the Pacific for years — you have a continuous and instantaneous readout of wind direction and speed. If these values are correlated with time and IAS (or Mach number) you can literally see the aerodynamic effect of half a knot of shear on the airplane. Shear is nothing more than a change in either wind direction or speed and you can never get away from it. Not to scare anyone with the last remark but it is literally true; no matter how stable or strong the wind is it is constantly changing in speed or direction or both which should probably called "minor shear," not the kind that can take an airplane out of the sky. If half a knot changes things on an 800,000 pound 747, will it effect the smaller airplane? In spades! Shear that causes the mischief is properly called "low level shear" and it has brought down many airplanes, large and small, but rather than calling them "shear accidents" they are more properly "thunderstorm/microburst" accidents. It's the microburst that's the really bad guy here.
The worst possible exposure is trying to penetrate the heavy rain outflow of a thunderstorm below 1,000 feet AGL on either approach or takeoff. Dry micro bursts on the other hand are usually less dangerous; so far as is known no one has yet been killed in one. Two key rules should keep you out of shear/micro burst trouble: Never penetrate the outflow of a thunderstorm at less than 1,000' AGL either on takeoff or landing. In a thunderstorm environment never base your go/no go decision on a report from a report from the airplane ahead that he "Had a smooth ride." If the guy ahead reports an airspeed fluctuation, expect yours to be at least three times as bad. If you're in such a hairy situation the worst mistake in the word is think the answer is to "just to get in on the ground and you'll be O.K." If on the ground in a potential microburst condition, set the brakes and wait it out.
I am in debt to pilot and good friend Captain Dave Akeman for synthesizing his extensive pilot experience and knowledge gained from exhaustive study of these phenomena into the above superb rules, and for much else I have learned from him about the phenomena. There's no doubt he is the most knowledgeable pilot in captivity. The propeller airplane is considerably less susceptible to difficulties produce by shear and/or microbursts, but that is rather academic as a practical matter. The demon can snatch propeller airplanes out of the sky pretty easily. If you want to delve more deeply into the subject look for a copy of the University of Chicago's T. Theodore (TED) Fugita's book "The Downburst," the one man who has literally dissected the shear/microburst factors in hundreds of related accidents.
Are you still flying?
Yes and no. Having lost my medical I cannot legally fly alone except in an ultralight or glider and have done considerable flying in both. Whenever I get the urge to fly — and that is often — my great boss and good Bob McIver, VP of Flight Operations for a hundred-airplane fleet flying for FedEx and UPS, etc.— who I have worked with as a consultant now for fourteen years — will offer me the chance to fly in any airplane in the fleet of fourteen different types. The best part? He won't take his share of any of our flights together since "he likes to watch me fly!"
Read Paul Soderlind's article "The Deadly Spiral."
Read John Deakin's column "Sometimes There's Bad Air Out There (Pelican's Perch #28)."