The De-Ice Man Cometh

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

2022 Version.


IT’S THAT TIME OF YEAR AGAIN: snowstorms, cancellations, the sights and sounds of that weird fluid splattering off the fuselage…


On the Ground:

Parked at the terminal, ice, snow, or frost accumulates on a plane the same way it does on your car. But while a cursory brushing or scraping is a safe-enough remedy for driving, it doesn’t work for flying, when even a quarter-inch layer of frozen material can alter airflow around the wing—highly important during takeoff, when speed is slow and lift margins are thin. The delicious-looking spray used to clean it away is a heated combination of propylene glycol alcohol and water. Different mixtures, varying in temperature, viscosity, and color, are applied for different conditions, often in combination: a plane will be hit with so-called Type I fluid (orange) to get rid of the bulk of accumulation, then further treated with Type IV (greenish), a stickier substance that wards off additional buildup.

While it might appear casual to the passenger, the spraying procedure is a regimented, step-by-step process. Pilots first follow a checklist to ensure their plane is correctly configured. Usually the flaps and slats will be lowered to the takeoff position, with the APU providing power and the main engines shut down. The air-conditioning units will be switched off to keep the cabin free of fumes. When deicing is complete, the ground crew tells the pilots which types of fluid were used, as well as the exact time that treatment began. This allows us to keep track of something called a “holdover time.” If the holdover time is exceeded before the plane has a chance to take off, a second round of spraying may be required. The length of the holdover depends on the kind of fluids used, plus the rate and type of active precipitation (dry snow, wet snow, ice pellets; light, moderate, heavy). We have charts to figure it all out.

Deicing fluid isn’t especially corrosive, but neither is it the most environmentally friendly stuff in the world. And although it resembles apple cider or a tropical fruit puree, I wouldn’t drink it; certain types of glycol are poisonous. At upward of $5 a gallon, it is also very expensive. When you add in handling and storage costs, relieving a single jet of winter white can cost several thousand dollars. A growing number of airports recycle deicing fluid. It’s a complicated process, but it beats letting the goop seep into the water table or drain into lakes and rivers.

Another method is to tow aircraft into specially built hangars equipped with powerful, ceiling-mounted heat lamps. JetBlue has such a hangar at JFK. In some ways this is a greener technique, though it uses hideous amounts of electricity.


In the Air:

Under the right combination moisture and temperature, icing also can occur during flight. It tends to build on the forward edges of the wings and tail, around engine inlets, and on various antennas and probes. Left unchecked, it can damage engines, throw propeller assemblies off balance, and disrupt the flow of air over and around the wing. In a worst-case scenario, it can induce a full-on aerodynamic stall.

The good news is that all commercial aircraft are equipped with devices to keep these areas clean. On propeller-driven planes, pneumatically inflated “boots” will break ice from the leading edges of the wings and horizontal tail. On jets, hot air from the engine compressors is ducted to the wings, tail, and engine intakes. Windshields, propeller blades, and the different probes and sensors are kept warm electrically. These systems use redundant power sources and are separated into independently functioning zones to keep any one failure from affecting the entire plane.

Airframe ice comes in three basic types: rime, clear, and mixed. Rime is the most frequent one, appearing as a sort of white fuzz. The rate at which ice accretes is graded from “trace” to “severe.” Severe icing, usually associated with freezing rain, can be a killer. It’s also very rare, and it tends to exist in thin bands that are easy to avoid or fly out of. On the whole, inflight icing is considerably more of a threat to smaller, noncommercial planes than it is to airliners. Even in the heaviest precipitation, seeing more than a trace amount of rime on a jet is uncommon.

Planes also have sophisticated anti-skid systems to help deal with slick runways. And if you’ve looked closely, you’ve seen that most runways are cut laterally by thousands of thin grooves, spaced inches apart, to help with traction. When it’s icy or snowy we get braking reports, graded 1-5, or from “good” to “nil,” prior to taking off or landing. Anything below a 2, or if described as worse than “poor,” and the runway essentially becomes unusable. Slippery conditions reduce the amount of crosswind we’re allowed to take of or land with, and a runway will be further off-limits if the depth of snow or slush exceeds a certain value. It varies by aircraft type and carrier-specific rules, but more than about three inches of dry snow on a runway, or a half-inch of the wet stuff, and you aren’t going anywhere until it’s plowed.

I’ve made my share of wintry-weather landings. One thing that always surprises me is the way in which fresh snowfall can make a runway difficult to see and align yourself with. In normal conditions the runway sits in stark contrast to the pavement, grass, or whatever else is around it. When it’s snowing, everything is white. Runways are outfitted with an array of color-coded lighting. Most of the time you pay only cursory attention to these displays. That is, until the moment you break from a low overcast, just a few hundred feet over the ground with a half-mile of visibility, and find yourself confronted with a landscape of undifferentiated whiteness. Those lights and colors are suddenly very helpful.


Accidents and Incidents:

There have been tragedies over the years in which planes attempted takeoff with iced-over wings. Most recent was a 1992 USAir incident at LaGuardia. Nine years earlier was the infamous Air Florida disaster in Washington, DC, when in addition to ignoring buildup on the wings, the crew failed to run the engine anti-ice system, allowing frozen probes to give faulty thrust readings. On Halloween night in 1994, sixty-eight people died aboard American Eagle flight 4184 — a crash attributed to a design flaw, since rectified, in the ATR-72’s deicing system. Other planes have gone skidding off the end of snowy runways. Culprits have included erroneous weather or braking data, an unstable approach continued when it should have been broken off, the occasional malfunction, or any combination of those things.

I can’t tell you there will never be another ice-related accident. But I can assure you that airlines and their crews take the issue a lot more seriously than they used to. We’ve learned a lot — much of it the hard way — and this has carried over into a mindset, and more careful procedures, that leave little to chance.

If it seems like the effects of winter storms become worse, that’s because they have. When I was a kid growing up near Boston, a few inches of snow at Logan Airport meant almost nothing. Nowadays, the slightest dusting and the airport goes bonkers with cancellations and delays. What’s happened, for one, is that the amount of air traffic has more than doubled since then. In the 1980s, closing a runway for 35 minutes for plowing had comparatively mild repercussions. Today, hundreds of flights are impacted.

Airlines also have become more conservative when bad weather looms, preemptively readjusting their schedules before the brunt of any storm moves in. This is unfortunate if you’re one of those whose flight is canceled in advance, but things would be a lot worse, for a lot of people, had the airline attempted to push through. And what’s happening in one part of the country affects flights, and their passengers, further down the chain, in cities across the nation and the world. Drawing down the operation in one location protects passengers elsewhere.

When it gets bad, airline workers don’t enjoy the chaos any more than passengers do. Pilots and flight attendants often live in cities far from their crew bases, and have to fly in to catch their assignments. With a storm looming, that means leaving 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. How do you turn what was supposed to be a 24-hour European layover in into a six-day vacation, as happened to me a couple of winters ago? Easy, just send a snow hurricane roaring through the Northeast. While the rest of you were stranded on tarmacs, sleeping under benches and sucking on discarded Chick-fil-A wrappers, I was sightseeing and sipping hot chocolate.

Not to rub it in or anything.


Iceman photo by the author.

“When you’re sitting on the tarmac while a guy in a hovering pod floats over you, twin beams of light piercing the murk of de-icing fluid. That’s my airplane fantasy. I want to be that guy!”

— Peter Hughes, Ask the Pilot fan and bassist for the Mountain Goats.


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50 Responses to “The De-Ice Man Cometh”
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  1. Carlos Si says:

    Hahahahahah, “not to rub it in”. There’s a lot of rubbing there. Would hate to be on the active end of that snowstorm.

  2. wilson says:

    Pilots vermoose when there’s weather and fear of weather. Telling.

  3. Glenn Baxter says:

    It’s been a few years and I don’t remember the airport, but it was in the NE and we had to go back for de-icing 3 times due to the lineup for takeoffs.

  4. Rob c. says:

    How can you complain about the smell of Venice when you have been firmly lodged between Patrick’s butt cheeks for so long?

  5. Richard Taylor says:

    I always enjoy reading your work. I especially enjoy the more technical columns. Sometimes they scare the hell out of me but they’re
    always informative.

  6. Julianne Adamik says:

    I just LOVE your blogs! Not only are you a great writer, but I always learn something I didn’t know about airplanes, airports or flying. Now that I’m retired I don’t travel as much as I did in the past, But, when I do it’s for pleasure, not work! Still, I find myself going somewhere about once a month. The best part is when I see the flight delayed or cancelled notice come up on the board my response now is…”whatever” instead of “shit!”

  7. Aviation Safety Research & Development has developed an innovative hazardous chemical free method for deicing aircraft, with the capability of virtually eliminating most flight delays and cancellations. The unique state-of-the-art ice detection features of our design, and our principal ground operations safety protocol will make air catastrophes due to undetected ice buildup on the wings during takeoff a thing of the past. We have Incorporated all reported recommendations of the ACRP ‘Airport Cooperative Research Program’ deicing practices, sponsored by the Federal Aviation Administration. Our innovative method plan adheres strictly to the new/revised guidelines and regulations issued August 5, 2016 for the winter of 2016-2017, in addition we have also implemented into method plan the FAA published long-range “Wish List” of certain safety protocols including, aircraft communications addressing and reporting system (ACARS) data link system of aircraft to relay deicing information to the flight crew. Unfortunately the fixed base of operation ground deicing operations contractors, airport decision-makers and the industry’s manufacturers of deicing equipment have been ignoring this valuable extensive and informative research information available since 2009 paid for by millions and millions of taxpayer dollars. The aviation industries complacency to continue to do business as usual, contributing to loss of life and extremely adverse effects on our environment will no longer be a

  8. Dave says:

    Ever seen the show “Ice Pilots” where they deice the plane with push brooms, scrapers and a mop for the propylene glycol?

  9. eric says:

    They are still looking for the Metcalfs from World Airways 30, slid off the Logan runway in 1982.

  10. Shaun says:

    I remember 5 years ago we had a dreadful snowstorm in northern Europe. I was in London waiting to fly to Dubai with Emirates, and our plane had to be de-iced three times, while we waited for about 5 hours in the A380 plane. Given how expensive it is to de-ice a plane, there seemed like shocking communication between the de-icing and then getting a slot to take off. Made it in the air, but some planes didn’t want to go and others did. It all seemed very confused.

  11. JamesP says:

    “Not to rub it in or anything.”

    Oh, (bleep) you! LOL Actually, I’m quite envious – the only time I got stuck anywhere due to weather was in Bakersfield, CA, when it snowed heavily up on the Cajon Pass and the road was closed. I’d take Bruxelles over Bakersfield any day. Hell, I’d rather be in Philadelphia!

  12. Doug says:

    Always interesting.
    I recall a few years ago some neighbors complaining about operations at a former Air Force Base. Some said they were told the AFB was closed, when in fact it was turned over by the military to civilian use.
    People being people, someone decided to raise a stink and called out an airport “expert” to talk about how airport operations harm people. He claimed, among other things, that de-icing fluid rains down on communities from planes taking off and we would all surely suffer. Good to know that fluid is basically harmless. Oh, did I mention I live in the Phoenix area where de-icing is unheard-of? That “expert” was a first-class moron.

  13. Marc Erickson says:

    Umm – Can I suggest “De-Ice Man Cometh” as the title? 😉

  14. Fletcher says:

    Wx. Freezing rain
    Aircraft b717
    Deice operation: no type 1, only type 4 used on already contaminated aircraft.

    Aircraft dispatched

    Your thoughts?

    Actual outcome: aircraft returned to gate due to EOB limit.

  15. Cliff says:

    Hi Patrick, good posting as usual. You made mention of supercooled fuel in the wings. Why is fuel supercooled, and where does that cooling take place? Thanks!

  16. Good choice on Ghent. I’m a huge fan of Belgium after my visit in October (just weeks before everything went crazy … even stayed at a hotel in Molenbeek).

  17. Gavin Brent says:

    With regard to flight 4184…

    ‘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,’

    Please could you explain ‘aileron hinge moment reversal’? This I understand led to the above disaster as a result of the ice build up on the wings. Many thanks


  19. Kevin B says:


    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)

    • wagga says:

      What is this deicing you speak of?

      Is ice like the stuff in the ‘fridge?

      I live in Cairns, Far North Queensland.

      Yes, we do occasionally get snakes on the plane.

    • ZenitFan says:

      >>. . . I was thinking what do I do if we start the take-off roll without flaps?<<

      Two-word answer: You crash, like Delta 1141 at DFW on 8/31/88. (Fortunately the vast majority of passengers & crew survived.) The crew were so busy talking about extraneous stuff during the checklist that they forgot to extend the flaps.

      I vividly remember that crash because I was the wx observer on duty that morning.

  20. 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?

    • Alastair says:

      It’s to do with scheduling. Say you only have enough passengers for four or five flights a day between two cities, A and B, which are an hour apart. The aircraft operating the first flights in both directions would end up sitting there for hours waiting for the return flights. It’s far more efficient for those two aircraft to operate a different service onto other destinations and then have other aircraft fly in to operate the next flights between A and B.

      Aircraft are expensive things and aren’t earning money whilst they’re sitting on the tarmac.

  21. 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.

  22. 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 ( 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…

  23. 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.

  24. 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.

  25. 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.

      • Saranda says:

        You’re correct in your comparison of Ghent and Bruges, and this is why I avoid Europe like the plague in the high season. 🙂

    • Frank S. says:

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

  26. 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:

    Love the book!


    • 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.

  27. chris says:

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

  28. 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.

  29. 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.

    • Roger Wolff says:

      Most of the wing does not “impact” the freezing rain or whatever it is that accumulates on the wing. This means that once you take care of the leading edge, the problem is fixed.

  30. 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.

    • queenzelda says:

      I caught a flight out of LHR at the beginning of the January 2010 storms before the delays and cancellations got so bad. The Qantas pilot announced that part of the delay was that LHR only has three deicing machines and that due to the current weather both wings had to be deiced simultaneously on the A380 – this meant that we were delayed waiting for two machines to come available. Clearly infrastructure is an issue. In a relatively mild place like London there clearly isn’t need for additional capacity except in extreme weather. (But then again in the UK trains don’t run if it rains, snows, is too hot or there are leaves on the tracks)

  31. 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.

  32. 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…

  33. 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!

  34. 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.