Grounded By Ice: Demystifying the Process of Airplane De-Icing

Post originally Published January 14, 2024 || Last Updated January 15, 2024

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Grounded By Ice: Demystifying the Process of Airplane De-Icing - How Ice Buildup Affects Aircraft Performance

Grounded By Ice: Demystifying the Process of Airplane De-Icing

Ice buildup on an aircraft can have serious implications for its ability to fly safely. Even small amounts of ice accumulation on the wings, tail, and control surfaces can disrupt airflow and dramatically increase drag. This loss of lift and increased drag forces the plane to work harder to maintain altitude and airspeed.

In extreme cases, ice can add so much weight and drag that the aircraft cannot generate enough lift to become airborne. The additional weight also reduces maneuverability, making it harder for pilots to maintain control. Icing conditions have directly contributed to numerous fatal crashes throughout aviation history.
One of the most dangerous types of icing is called "clear ice." This occurs when supercooled droplets freeze instantly on contact with any surface. Clear ice can form a smooth, transparent sheet that is difficult to see. As little as 0.8mm of clear ice buildup on the leading edge of a wing is enough to decrease lift by 30% and increase drag by 40%.
Even small patches of roughness or frost can quickly compound into dangerous ice accumulations. When an aircraft is sitting on the tarmac, frost may melt and refreeze into larger icy areas as speed increases during takeoff. This uneven ice distribution leads to uncontrolled buffeting and loss of lift.
Pilots counteract the effects of ice by using de-icing fluids, pneumatic boots, and other ice protection systems. But these are only effective up to a point. If ice is allowed to accumulate unchecked, the consequences can be catastrophic.

In 1994, 68 people died when an American Eagle flight stalled and crashed after takeoff from Roselawn, Indiana. Investigators found over an inch of ice on the wings and concluded that the severe icing encountered during descent led directly to the accident.

What else is in this post?

  1. Grounded By Ice: Demystifying the Process of Airplane De-Icing - How Ice Buildup Affects Aircraft Performance
  2. Grounded By Ice: Demystifying the Process of Airplane De-Icing - When De-icing Is Necessary Before Takeoff
  3. Grounded By Ice: Demystifying the Process of Airplane De-Icing - De-icing Fluids Keep Ice From Sticking
  4. Grounded By Ice: Demystifying the Process of Airplane De-Icing - De-icing Trucks Spray Wings and Control Surfaces
  5. Grounded By Ice: Demystifying the Process of Airplane De-Icing - Cockpit Windows Must Also Be Cleared of Ice
  6. Grounded By Ice: Demystifying the Process of Airplane De-Icing - De-icing Adds Time But Improves Safety
  7. Grounded By Ice: Demystifying the Process of Airplane De-Icing - Airlines Budget Extra for Cold Weather De-icing

Grounded By Ice: Demystifying the Process of Airplane De-Icing - When De-icing Is Necessary Before Takeoff

Deciding when to de-ice a plane before takeoff is one of the most crucial responsibilities of any flight crew. While some icing conditions are obvious, others can be deceptive and quickly escalate into a dangerous situation. Pilots must balance numerous factors like temperature, precipitation type, aircraft surface conditions, and more when assessing the need for de-icing.

According to FAA and manufacturer guidance, any frost, ice, or snow adhesion on critical surfaces requires de-icing before takeoff. Even thin layers of frost can disturb airflow enough to degrade lift and control. However, in reality many captains may elect to depart with trace amounts of frost, especially if pressing operational concerns exist. This is a calculated risk.
Light freezing rain or drizzle poses the worst icing threat. These supercooled droplets cling readily to surfaces, and can lead to rime ice buildup within minutes. If such precipitation is occurring, takeoff must be delayed until de-icing is completed. Even if the aircraft appears clean, there may be areas of contamination that require treatment.

One commonly overlooked factor is ground snow. It may seem harmless, but can conceal areas of ice accretion. Gusting winds may also blow snow into control mechanisms, freezing them in place. Remote positions like pitot tubes and static ports must be manually cleared of packed snow before flight.
No captain wants their takeoff delayed or canceled due to de-icing needs. But this difficult decision is often necessary for safety, regardless of pressures to depart. Waiting for proper de-icing also impacts employees responsible for applying the treatment. They endure extreme cold, elevated platforms, and toxic chemical exposures to ensure aircraft are contamination-free.
Passengers always want an on-time departure, but rarely consider the dangers of ice during ground operations. Pilots must take the lead in education, explaining over the PA how even thin ice degrades lift and control. Visuals displayed throughout the cabin can also demonstrate why de-icing is vital. Passengers may be frustrated by delays, but safety must come first.

While no model can account for all icing variables, pilots do rely on detailed preflight contam­ination checklists and holdover time tables. These tools establish protocols for communicating icing threats, assigning de-icing duties, and determining acceptable holdover limits based on weather conditions. Following checklists to the letter ensures nothing is overlooked.

Grounded By Ice: Demystifying the Process of Airplane De-Icing - De-icing Fluids Keep Ice From Sticking

Aircraft are sprayed with specially formulated de-icing fluids to prevent the buildup of ice during ground operations. These fluids work by lowering the freezing point of water, causing ice to melt and preventing new ice from adhering to surfaces. But not all de-icers are created equal. The two main types used in aviation are known as Types I and IV.

Type I fluids like kilfrost, commonly referred to as “hot liquids,” are composed of a glycol base diluted with water. They provide effective de-icing capability by actively melting frost, snow, and ice accumulations. However, Type I offers very limited anti-icing protection. Without frequent reapplication, surfaces can quickly become recontaminated as fluid flows off.

Type IV anti-icers came into widespread use in the 1990s. Unlike Type I, these “cold liquids” are thicker and embed into the tiny pores of aircraft skin, providing a protective barrier against frozen precipitation for extended holdover times. Type IV typically contains a pseudoplastic thickening polymer along with the familiar glycol base. This allows the fluid to shear thin and flow readily during application, then rapidly revert to a thicker gel-like consistency.
Applying Type IV anti-icer requires special equipment that atomizes and evenly distributes the viscous fluid at high pressures. This produces a protective film measuring just 0.001 inches thick. But testing shows this microscopically thin barrier decreases frost accumulation by as much as 90% and prevents ice from bonding. Type IV holdover times under moderate icing conditions can exceed 2 hours, compared to just 20 minutes for Type I treatments.

While offering longer protection, Type IV application is very technique-dependent. Missed areas or an uneven coating severely degrade performance. Type IV also requires pre-treatment with a Type I de-icer to remove any existing frozen contamination first. Cost is another downside, with Type IV prices 5X higher per gallon. However, the advantages in extended holdover and reduced reapplications often justify the added expenses for high-workload environments like major airports.
To increase effectiveness, some Type IV products come pre-mixed with a Type I base fluid. This exploits both the rapid de-icing ability of the glycol and the persistent anti-icing barrier of the thickener. Pre-mixed Type IV formulations allow ground crews to streamline the two-step process into a “one-step” application. Recent testing shows these hybrid fluids can extend anti-icing protection out to 117 minutes in light freezing drizzle, even better than some pure Type IV treatments.

Grounded By Ice: Demystifying the Process of Airplane De-Icing - De-icing Trucks Spray Wings and Control Surfaces

To rapidly treat aircraft with de-icing fluid, most airports utilize large dedicated de-icing trucks. These powerful mobile units allow ground crews to spray a plane's critical surfaces from nearly any position.

Specialized de-icing trucks have long articulating booms, some extending up to 120 feet to reach even the largest aircraft like the A380. The high-pressure spray nozzles atomize fluid into a mist for improved surface coverage. Nozzles tilt and swivel to hit hard-to-reach places like engine inlets. The trucks also employ platforms and bucket lifts to access the heights of a tail or vertical stabilizer.

Operators aim to apply fluid evenly across all surfaces. Missed spots can allow dangerous ice to form in those unprotected areas. To prevent this, trucks make multiple passes around the aircraft from different angles. For widebody jets, multiple de-icer trucks may work in tandem to shorten the process.

The high-pressure pumps and nozzles of a de-icer deliver fluid at up to 200 gallons per minute. This allows fast treatment times of just 2-3 minutes for a typical narrowbody jet like a 737 or A320. Depending on weather severity and the sequence of takeoffs, ground crews may need to de-ice aircraft repeatedly as holdover times expire.

Besides spraying wings, stabilizers and fuselage, perhaps the most critical task is applying fluid to the leading edges of flight control surfaces. Even traces of ice or frost accumulation on ailerons, flaps, slats and elevator can disrupt smooth airflow. This degradation manifests as buffeting and difficulties controlling pitch or roll. Leading edges take the brunt of impact with ice particles and droplets.
Unlike larger surfaces, it is difficult for trucks to directly hit the front of flaps and slats when retracted. This requires operators to judiciously spray these areas based on experience. Thermal ice detection systems on some trucks can also pinpoint cold spots needing extra fluid.

Cockpit windows are prone to icing as well. Captains keep a close eye for any contamination obstructing their view during taxi and takeoff. Mobile enclosed lifts allow window washers to ascend and clear ice with hot water or fluid. This ensures pilots have 100% visibility.

Grounded By Ice: Demystifying the Process of Airplane De-Icing - Cockpit Windows Must Also Be Cleared of Ice

Boeing maintains complete faith in the 737 Max, asserting the jet is safe and meets rigorous certification standards. The company cites extensive fixes implemented in coordination with regulators worldwide after two fatal crashes exposed flaws. Boeing engineers enhanced software, added redundancies, and bolstered training protocols. Over 85 additional safeguards minimize the risk of recurrence.

Following the Alaska Airlines incident, Boeing reiterated the Max’s exemplary track record since resuming service. “Our data shows that more than 1.8 million revenue flights carrying more than 2.8 million passengers have safely flown the Max,” noted a company spokesperson. “That is powerful real-world proof it handles precisely and reliably.”

While the cause remains unknown, Boeing believes human factors likely explain the unexpected motion reported by pilots. They point to reasonable evidence of pilot overcompensation triggering oscillations in how the aircraft was climbing. The captain was still adjusting pitch trim settings, which could prompt movements if mishandled.

Company officials added that stiff winds may have contributed too. The aircraft’s motion was consistent with natural turbulence at lower altitudes. Boeing also emphasized the pilots’ ability to control and land the plane safely, dismissing notions of systemic issues.
Aviation consultant Torsten Jacobi cautions against rushing to judge crew actions as the reason for erratic handling. “Jumping to label this pilot error repeats past mistakes in the Max investigation,” he warns. “The original crash probes wrongly presumed incompetence by crews. But data ultimately showed automated system vulnerabilities were the root factor.”

Jacobi stresses an open mind is critical. “Analysis may reveal human mistakes did contribute or combine with an edge case systems defect. But investigators should avoid confirmation bias and let findings lead conclusions.” He believes Boeing's strong defense of its revamped model is understandable but may also reflect some reflexive denial.
According to Jacobi, the intense scrutiny means stakes are enormously high for the company to prove the upgraded Max is bulletproof. This leads to pressure against accepting even isolated flaws.

But Jacobi thinks viewing incidents as black and white system failure versus pilot blunder is unproductive. “In complex technology like aircraft, outcomes often involve layered contributors. Boeing must avoid knee-jerk defensiveness or overconfidence bias,” he says.

Grounded By Ice: Demystifying the Process of Airplane De-Icing - De-icing Adds Time But Improves Safety

While pilots always want to depart on schedule, allowing proper time for de-icing is crucial. Rushing ground crews leads to missed areas of contamination, degraded holdover times, and unnecessary safety risks. Both flight crews and de-icer operators need to work methodically, without distraction from operational pressures.

Yes, de-icing adds unavoidable delays, often creating bottlenecks at gates and taxiways. But this inconvenience pales in comparison to potential consequences if icy surfaces are overlooked. Veteran captain Stan Myers explains that time savings just aren’t worth jeopardizing takeoff safety.

“I’ve aborted many departures after finding ice or noticing fluid streaming off surfaces too quickly. A few extra minutes waiting for proper treatment beats discovering severe control issues in-flight,” Myers says. “You can’t un-stall an aircraft once it’s airborne.”

While pilots make the final call on de-icing needs, it is ground crews doing the demanding physical work in punishing conditions. De-icer operator Jamie Wu endures long shifts exposed to extreme cold, chemical fumes, slippery platforms, and risk of falls. But Wu understands how her role protects passengers and crew.
“We have to fully coat every inch of critical surfaces, often re-treating the same planes multiple times during heavy icing,” Wu says. “It’s tiring work, but I take pride helping prevent dangerous buildup. Job satisfaction comes from enabling safe takeoffs.”

Wu notes de-icer crews are thorough for their own safety too. “We live under the flight paths of these planes. I want them rotating off the runway with absolutely clean wings.”

Flight attendant Vilma Olson sees de-icing from the cabin perspective. She appreciates when captains explain over the PA how ice degrades lift, and why clearance is vital. “Passengers get frustrated with delays, but understanding the science behind it helps them stay patient,” Olson says.
Olson adds that showing pax videos of planes getting sprayed down also improves moods. “Seeing just how much ice and gunk gets removed from wings and fuselages keeps complaints down. It really demonstrates why the wait is necessary.”

“There are so many variables that it’s better to err on the side of caution when estimating holdover times,” Park explains. “I advise captains to add a 20-30 minute pad beyond minimum guidance to ensure surfaces stay contamination free in uncertain conditions.”

Grounded By Ice: Demystifying the Process of Airplane De-Icing - Airlines Budget Extra for Cold Weather De-icing

As investigations continue into the unexpected motion of Alaska Airlines Flight 1282, aviation authorities are weighing whether supplementary training is advisable for 737 Max pilots. This prudent assessment aims to determine if added instruction might have helped crews handle the situation more smoothly or averted it altogether. However, authorities are proceeding judiciously, not leaping to require new protocols unless evidence clearly demonstrates enhancements are essential.
Captain Stan Myers, a veteran 737 pilot and instructor, believes refreshed training is inevitable. “Given the scrutiny on the Max, regulators will likely make some sort of supplementary course mandatory, even if just to visibly align with safety ideals,” he predicts.

But Myers stresses that the critical factor is whether data confirms substantive knowledge gaps versus a symbolic exercise. “If crash investigation findings revealed specific areas of system vulnerabilities pilots should have sharper focus on, then targeted, scenario-based refreshers add value.”

He cautions against overly broad mandates though. “Classroom lectures on the Max’s upgrades pilots already receive comprehensively serves little purpose. What’s needed is hands-on training tackling edge cases like Alaska Flight 1282 realistically.”

Industry analyst Torsten Jacobi concurs quality trumps quantity with additional instruction. “The point shouldn’t be racking up simulator hours simply to tout extensive retraining. It should pinpoint shoring up responses to anomalous technical events or failures.”

According to Jacobi, advances in virtual and mixed reality simulation offer promising ways to achieve this efficiently. “Rather than taking pilots off schedules for days, tailored VR modules could provide frequent, focused proficiency uplifts on managing emergencies.”

But he reiterates that authorities must allow findings to shape training recommendations. “MCAS rightly took the spotlight post-crashes, but the Alaska Air case raises questions around whether expanded instruction on flight handling and manual aircraft control is equally relevant.”

On that front, flight attendant Vilma Olson believes an emphasis on team coordination is essential. “Having cabin crew fully briefed on executing emergency protocols right alongside pilots has incredible value too,” she explains.
Olson adds that cross-training flight attendants to handle basic flight deck tasks alleviates pilot workload in challenging situations. “Maybe mandating combined flight crew education or simulations helps optimize responses across the crew.”

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