The De-Ice Man Cometh


Snow, Ice, and Airplanes. Everything You Need to Know About the Travails of Winter Flying.

Deiceman.jpg

IT’S THAT TIME OF YEAR AGAIN: storm warnings, preemptive cancellations, the mist and spray of that strange heated fluid splattering off the fuselage. Airplanes and winter don’t always mix well.

The flying part is easy. Sure, low visibilities, strong crosswinds, slick runways, potential icing — all of these things are challenges for pilots and cause air traffic backlogs, but as a rule they aren’t anything that airplanes or their crews can’t handle. It’s not the in-the-air aspects of a snowstorm that cause chaos, it’s the on-the-ground aspects: Runways and taxiways need to be plowed and treated, while tarmac logistics go to hell as snow and ice accumulate. Luggage and cargo handling, fueling — everything slows to a crawl as personnel and ground equipment become bogged in the slush.

Planes, meanwhile, cannot take off with ice or snow adhering to the wings. Parked at the terminal, an aircraft collects precipitation the way your car does — via snowfall, sleet, freezing rain or frost. (Thanks to supercooled fuel in the wings, frost can form insidiously even with temps above freezing.) The delicious-looking spray (apricot-strawberry) used to remove it is a heated combination of propylene glycol alcohol and water. It melts away existing snow or ice, and prevents the buildup of more. Different fluid mixtures, varying in temperature and viscosity, are applied for different conditions.

While it seems pretty casual to the passenger, the spraying procedure is actually a regimented, step-by-step process. Procedures vary depending on the type of fluid used, ambient temperature, plus the rate and type of precipitation. The airplane needs to be configured a certain way, and pilots stay in contact with the deicing coordinator throughout the process. The deicing guide in my manual is about 20 pages long, including several checklists, graphs and charts. We keep track of something called “holdover time” to help determine if and when a second round of deicing is necessary.

With fluid costing upwards of $5 per gallon, airlines loathe snowstorms almost as much as strikes, wars, and recessions. When handling and storage costs are considered, relieving a single jet of unwanted winter white can cost tens of thousands of dollars.

It’s money well spent, however, because ice on an airplane is potentially hazardous, especially when adhering to the wings. The monster isn’t the weight of the frozen material, but the way it disrupts airflow over and around a wing’s carefully sculpted contours, robbing a plane of lift.

Icing also can occur during flight. Under the right combination moisture and temperature, it can form along the leading edges of the wings and tail, along engine intakes and propeller blades, as well as on windscreens, probes, and various other surfaces. Left unchecked, heavy icing can damage engines, throw propeller assemblies off balance, and, just as it does on the ground, steal away precious lift. Planes are most susceptible during takeoff and landing, when speed is slowest and the lift margins already slim.

 

 

There have been several ice-related accidents over the years. In 1992 a USAir jet crashed at La Guardia after attempting takeoff with inadequately deiced wings. There was also the infamous crash of Air Florida flight 90 in Washington, DC, in 1982, when in addition to buildup on the wings, frozen-over probes gave a faulty, less-than-actual thrust reading after the crew failed to run the engine anti-ice system. And in 1994 sixty-eight people died in what remains the deadliest-ever mishap involving a regional aircraft — the crash of American Eagle flight 4184 The plane, an ATR-72 turboprop, had made several circuits of a holding pattern in freezing rain, when suddenly it was thrown into an uncontrollable roll and plummeted from the sky, disintegrating in a soybean field near the town of Roselawn, Indiana. A design flaw in the ATR’s wing deicing system was later discovered, and corrected.

The good news is that the most recent of those accidents was a long time ago. Those were tough lessons to learn, but airliner crashes brought on by icing have become exceptionally rare. Most inflight ice encounters are brief and routine, posing little if any danger, and all modern commercial aircraft are equipped with sophisticated deicing equipment for the rare times when things become more serious. Propeller blades, probes and windscreens are kept clear electrically; engine intakes and wing leading edges are heated using air bled from the engines, or are deiced through a series of pneumatically inflated “boots” that break away accumulation. These systems use redundant sources and are separated into independently operating zones to keep any single failure from affecting the entire plane.

Is it just me, though, or have winter storm delays become worse than they used to be? When I was a kid, a few inches of snow meant almost nothing. By comparison, nowadays, two inches of snow at Logan and the entire airport seems to go bonkers. What’s happened, maybe, is that our snow removal techniques haven’t kept up with the growth in air traffic. There are roughly twice as many planes flying as there were a quarter century ago, while our airport and air traffic control infrastructures have hardly changed. In the 1980s, closing a runway for 35 minutes so it could be cleared and treated had comparatively mild repercussions. Today literally hundreds of flights can be affected.

Meanwhile, airlines are becoming more and more conservative when bad weather looms, preemptively readjusting their schedules before the brunt of any storm actually move in. This is highly unfortunate if you’re one of the those whose flight is delayed or canceled, but things would likely be a lot worse for an even greater number of people had the airline attempted to push through. And remember that planes don’t simply fly back and forth between the same two cities; what happens in Boston or New York affects flights, and their passengers, further down the chain, in cities across the nation and the world. Drawing down the operation in one location helps protect passengers elsewhere.

Aside from the complications of ice and snow, airplanes perform better in colder weather. Some planes do have limits that prohibit operation when ground temperatures fall below a certain point (the complications here involve starting the engines, cold-soaked oil and such), but engines produce power more efficiently, and wings generate lift more efficiently, in colder, denser air. Very low temperatures occasionally result in delays and cancellations, but this more about the effects on support infrastructure: airport personnel and ground equipment — the various people, vehicles and machinery that go into supporting an airline’s operation. You can’t load and unload the luggage, fuel the tanks or cater the cabins if the baggage carts and belt-loaders aren’t working, the trucks aren’t starting, and employees are so cold they can hardly move.

Last winter was particularly nasty, with several big storms and thousands of cancellations. We’ve been lucky so far this season, but it’s only December.

For what it’s worth, crews don’t enjoy the chaos any more than passengers do. Airline crews often live in cities far from their crew bases, and must fly in to catch their assignments. With a storm looming, that means commuting in many hours early — sometimes a day or more ahead of schedule. Or, on the back end, we can find ourselves unable to get home again until things return to normal.

Once in a while, though, the timing works to our advantage. For example, how do you turn one pilot’s scheduled 24-hour layover in Brussels into a five-day European vacation? Easy, just send a snow hurricane roaring through the Northeast corridor, as happened a couple of winters ago. While the rest of you were stranded on tarmacs, sleeping under benches and sucking on discarded Chick-fil-A wrappers, I was sipping on hot chocolate and hopping on the train up to Ghent for a view of the newly restored Van Eyck altarpiece at St. Bavo’s Cathedral.

Not to rub it in or anything.

 

If you enjoyed this discussion, chances are you’ll love the book.

 

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25 Responses to “The De-Ice Man Cometh”
  1. Simon says:

    You raise a good point about winter storms appearing to have a bigger effect than they used to. I think you’re definitely right that snow/ice removal has not kept pace with the increase in air travel.

    Another issue might be low-cost air travel. I fear in the race to the bottom we’ve given up on all redundancy and error margins for the sake of the cheapest air fares. Sure we travel cheap, but just wait until one tiny thing goes wrong. Suddenly everything grinds to a halt because there’s no snow plows available, no relief crew around, no replacement aircraft, no extra ground staff, etc. In the quest to become as efficient as possible, we’ve trimmed away all our emergency ‘buffers’. This system might be cheap, but it’s the opposite of robust.

    • Alex says:

      Definetely. I remember being stranded (only a couple hours) in Kansas City International because of snow. There were only a few inches on the ground, and it was relatively light by the time I got there, but all I saw clearing the tarmac was one regular truck with a plow attached. Being from Wisconsin I took for granted that any airport that might experience snow would have actual plows available.

  2. George says:

    Let’s also consider the totally unrealistic DOT fine imposed upon the hapless carrier that ‘strands’ its passengers by not getting them airborne within 3 hours of pushback: $27,500/pax X 100 pax = $2,750,000. At this rate, I’m surprised anybody operates flights in inclement weather.

    ‘Nice blog Patrick!

  3. Caz says:

    I’ve seen the Van Eyck that you mentioned in the article as well; his work was so intricate for the period that he painted in. I assume you’ve been to Antwerp to see the site of where he painted the St. Barbara? Has to be one of my favorite cities in the World…

  4. JK says:

    > in 1991 a USAir jet crashed at La Guardia after attempting takeoff with inadequately deiced wings. <

    I think you are referring to USAir Flight 405 — if so, it crashed in 1992, not 1991.

  5. John LM says:

    Hi Patrick

    Couple of questions in regards to de-icing, first: does the practice of de-icing a plane with what seems like could be a caustic mix degrade the plane in any way in the long run and do dispatchers rotate out planes that may have seen their share of de-icing in a certain time period? Second, in places like LAX I’ve heard of conditions (although very rarely) that require planes to be de-iced. I have to imagine though that they wouldn’t keep as many DI machines as on Northern seaboard so if a freak storm required dozens of planes to be sprayed would LAX come to a standstill? Or is that something that is regulated by the FAA and every airports needs a certain amount of machines on hand? Thanks as always!

    • Joe Latshaw says:

      Deicing fluid isn’t caustic. Propylene glycol is a gelling agent you find in many liquid soaps and detergents; it’s also sold as “pet-safe antifreeze” as it isn’t poisonous in reasonably quantities and it doesn’t have the sweet taste that attracts animals in the first place. Ethanol is simply alcohol.

  6. Rod says:

    Well thanks for not rubbing it in.

    I always wonder how hot bleed air inside the leading edge of a wing (or tail) can keep the ice liquified until it has departed the trailing edge.
    It must be as hot as hell.

    • Curt Sampson says:

      Well, I don’t know how hot hell is, but the bleed air from the engine comes out somewhere between 200 and 250 degrees Celsius. That may well be hot enough to boil any ice on the wing in to vapour. But regardless, ice adhering to the wing itself would be a problem for only a moment or two once they start to heat the wings with bleed air, because on a hot wing ice can’t form.

  7. Simon IOM says:

    I live in the Isle of Man and we are very lucky as we don’t appear to get the brunt of storms that happen worldwide and indeed just 40 or 50 miles away in the UK, so it is very rare to see any planes ever being deiced here. I was flying from the IOM to Belfast BHD Belfast City airport last February on a very frosty morning and looking out of the departure terminal window there were Dash 8 Delta’s and an ATR 72 actually getting deiced on the apron, I was flying on a LET 410 and no word of a lie, a man was on a little step ladder cleaning the windscreen with an ice scraper ..when I was boarding I spoke to one of the pilots who greet you and show you on board as there is no stewards just the two pilots, Czech I think He was by his accent, and I asked Him “are we not getting deiced” his reply was superb, ” No, its not necessary, its a little bit of frost, its not as if we are taking of from Norway or somewhere ”
    We departed and landed without any problems, but I loved his confidence, obviously quite experienced in cold conditions.

  8. chris says:

    Good tutorial about icing. This aviation enthusiast, non pilot, had a lot of fun learning about this phenomenon in its many forms.

    http://aircrafticing.grc.nasa.gov/courses_inflight.html

  9. Andy Nash says:

    Hi Patrick

    Here’s a link to my de icing photos on Flickr. In Vienna a person called “the iceman” … at least that’s what it says on the little truck with a ladder he drives says … comes up on the wing to check if the de-icing worked. I got some good photos of him a couple years ago, here are all my “de-icing” photo album on flickr:

    https://www.flickr.com/photos/andynash/sets/72157649266394157/

    Love the book!

    Andy

    • Patrick says:

      Yes, “iceman” is part of the jargon here in the States too. He’s the guy who supervises the deicing process, and who we stay in touch with via radio while during the spray-down.

      It could easily be a female, of course, though something about the word “icewoman” just doesn’t sound right.

  10. UncleStu says:

    I would have gone to Bruges. I fell in love with that gem of a place and spent three days wandering around with my jaw dropped and my camera in high gear. It’s a time machine, almost like a fairy tale come alive (like Venice).

    And the beer, especially the one that tastes like cherries. If you know the name of it, I’d sure like to get some.

    Warmest regards and bet wishes for the holidays.

    Me? I celebrate ChrismaHanuKwanzaka.

    • Patrick says:

      I’ve been to Bruges. I like Ghent better. Bruges is too much like an open-air museum. Ghent is less prissy and doesn’t have the tourist throngs. I’ve been to Venice several times as well. It’s a beautiful place but you really need to see it in the off-season, when the crowds thin out. In the summer it’s almost unbearable.

      • Rod says:

        Venice is the outdoor museum of all outdoor museums, with the tourists far outnumbering the locals every day of the year. I don’t think there is an off-season and more. Among the unbearable things in summer, of course, is the smell of the canals. Whoa.

    • Frank S. says:

      The Belgian beer that tastes like cherries is called ‘Kriek’.

  11. Randall says:

    I am surprised you did not at least mention Colgan 3407. Ice did not cause the crash, but it was a distraction that may have contributed to the loss of SA and poor airmanship that caused the crash.

  12. Glenn Normile says:

    Patrick, I’ve always enjoyed your stories & even bought both books. I share my winter flying story here. In 1998, I lived in Lower Merion, PA & my daughter was on her hs debate team. I was recruited to be the chaperone for a dozen kids travelling to Boston for a tournament at Boston Latin & Harvard. We arrived at PHL about 5am & could see ships on the river. Our plane was late arriving from wherever, so we were delayed several hours. Before we boarded a snowstorm arrived; the ships were invisible now. Finally we boarded, got de-iced twice, & then a funny thing happened. From the cockpit a pilot & a man in a suit emerged. They politely asked the passengers seated by one of the emergency wing exits to vacate their seats, then opened the door & the pilot held the other guy by his belt as he climbed out onto the wing. Panic began…there had been no announcement about what was happening. I realized they were checking for ice, but people wanted to de-plane. Eventually they got the door back into place, let the folks sit down, & went back up front. We began to taxi & finally an announcement was made that the FAA inspector had demanded to check the wing for ice before the plane could take off. We had a safe flight to Boston.

  13. Damien says:

    Hi Patrick,

    As usual, your article is really interesting. But I may disagree with you when saying “The good news is that the most recent of those accidents was a long time ago.”. I just cannot imagine that you forget about AF447 flight. Even if you explained a few weeks ago in a long tribune against a Vanity Fair story (http://www.askthepilot.com/automation-and-disaster/) that pilots, to make a long story short, did not understand what happened and so did not behave in a way to avoid the crash, it seems to me that the initial cause of the 3-minutes misunderstanding was a frozen Pitot probe.

    Am I wrong?

    Please apologize if you find mistakes in my comment, as english is not my native language…

  14. JuliaZ says:

    I was lucky to be on one of the very few flights that departed DFW last November, a few days before Thanksgiving, when Dallas had a freak ice storm. American canceled nearly all of its hundreds of DFW flights that day, starting in the morning long before the bad weather even hit. Our airline? Alaska. The pilot came on the PA, openly scoffed at the mildness of the weather, said we were waiting our turn for de-icing, and as soon as that was done, we’d be off, since the other airlines were “too chicken” to fly. The plane was absolutely full, of course, and in a rare display of SLF camaraderie, we spontaneously applauded once we were in the air.

    It was excellent to get home on a night when so many folks were stranded, but I wonder how much of this was due to pilot skill and the airline’s comfort level with bad weather, or if all of those flights could have completed safely? I’m guessing American canceled much of its schedule because of apron issues, crew problems, and lack of de-icing capacity, not because decision-makers at American really thought conditions were unsafe.

  15. JimBob says:

    “… planes don’t simply fly back and forth between the same two cities…”

    Why not? Wouldn’t that make it easier to isolate problems?

  16. Kevin B says:

    Patrick,

    Informative, as usual. I was flying out of EWR to DFW on AA on a snowy day and we were de-iced at the gate. I noticed as we taxied to runway 4 that the flaps were still retracted and we were getting close to our turn for departure and they still weren’t out much later than when they were normally deployed – It was one of those situations where you’d rather die than make a fool of yourself, but I was thinking what do I do if we start the take-off roll without flaps? Probably too late to go yelling and screaming up the aisle and we end up like Northwest out of DTW flying into the Avis rent-a Car facility. Of course, they did deploy the flaps and we went merrily on our way – Later I figured maybe you wait until the last minute so snow doesn’t accumulate on the flaps? (I wish I had thought of that earlier but at least I didn’t make a fool of myself)