Whether it’s by ground or through the air, inclement weather always presents problems when traveling.
But why is it so important to de-ice an airplane before takeoff? In November, a flight was substantially delayed coming out of Durango-La Plata County Airport because of a shortage of de-icing fluid.
But DRO Aviation Director Tony Vicari says that most of the time flights aren’t delayed based on plane de-icing alone. However, for safety purposes, it is crucial an aircraft go through the proper de-icing process.
According to NASA, 35 air carrier accidents worldwide have been attributed to inadequate ground de-icing, with 19 occurring in the United States in the last 25 years.
“Aircraft are manufactured and designed in a way to maximize aerodynamics and lift by their very function,” Vicari said. “And icing on any surface of the aircraft could potentially cause an issue in those areas that can either degrade lift, or actually freeze the control surface on the aircraft.”
A control surface is any part of an aircraft the pilot operates. These surfaces allow the plane to taxi, aviate, bank, accelerate, decelerate and land.
“An incomplete or insufficient de-icing process could potentially leave an aircraft open to a very significant safety hazard if it isn’t able to generate lift,” Vicari said.
The de-icing process is only used seasonally when temperatures drop. Vicari said every airline has different guidelines for when they de-ice a plane, but as a general rule it happens when temperatures drop below 40 degrees Fahrenheit.
When aircraft control surfaces become contaminated with ice, flight crews will notify airline ground crews to de-ice the plane.
The ground crews will use two separate fluids depending on the severity of the ice.
De-icing fluid is made up of propylene glycol mixed with water and heated to a minimum of 140 degrees Fahrenheit. The heated liquid is sprayed on aircraft surfaces at a high pressure level. This combination of heat and pressure melts and removes the ice from the aircraft surfaces.
Anti-icing fluid is also made from propylene glycol, but is much more viscous than de-icing fluid. This fluid is used during times of active precipitation or when the time between de-icing and takeoff is anticipated to be much longer. These anti-icing chemicals act to prevent precipitation from bonding to the aircraft surfaces after de-icing fluid has been applied.
De-icing is accomplished with a boom truck, where one person operates the vehicle and drives around the aircraft and the other operates the boom and sprays the fluid onto the aircraft. That process typically starts from one part of the aircraft and works 360 degrees all around it.
De-icing times will vary largely, from a light frost to heavy accumulations.
Vicari said the standard de-icing time is about 15 minutes, but that process could last up to 45 minutes when there is active snow.
“If you had an extended delay, it’s probably due to a compounding factor for other reasons,” he said.
He said instances where there are prolonged delays are created when there are ground delays or air control holds at major hubs because of a lack of visibility during a snowstorm.
Because airports limit capacity during storms for safety purposes, this can add additional travel time. Vicari said most of the time when long delays happen, a plane is being de-iced and waiting for air traffic control to release it to leave for places like Denver International Airport, which often receives snow.
Pilots are waiting to see if these airports have an open spot for them to land because of the limited capacity caused by winter storms.
Vicari said during winter months, airlines will often extend block hours for flights.
“Basically, it’s the time between closing the door on the aircraft and then ultimately landing at your destination,” he said.
This is often because there’s more maintenance, such as de-icing, that an aircraft must go through during winter months.
While Vicari has never personally de-iced a plane, he says it’s a hard job for those who do it at DRO.
“It is a cold, wet, sticky and generally tough job overall,” he said. “I think it’s important for folks just to have an understanding or maybe a bit of a patience for what they’re doing.”
De-icing for United Airlines flights is conducted by the ground handling vendor, United Ground Express, while de-icing operations for American Airlines is currently contracted to AvFlight, the fixed base operator at DRO.
The airport does not fulfill a direct service role in airline de-icing operations, but coordinates approved locations for aircraft de-icing on the airfield. DRO also collects and recycles used glycol.
“They’re doing the best they can to move through expeditiously and get airplanes out on time,” Vicari said.
tbrown@durangoherald.com
