Deicing Activities Research Articles

A discrete-event simulation tool for airport deicing activities: Dallas-Fort Worth International Airport

Aircraft deicing/anti-icing fluids (ADFs) are applied to remove and prevent icing on aircraft during taxi and takeoff. The Dallas-Fort Worth (DFW) International Airport uses deicing pads for deicing activities that collect and contain the spent deicing fluids for proper treatment or disposal. Local waterways receive ADF as “drip and shear” during the aircraft taxi on the runway and then takeoff. The glycol-based ADF serves as a nutrient for bacteria that grow exponentially, deplete dissolved oxygen (DO) from receiving waterways, and subsequently kill aquatic life. In this paper, we present a data-driven discrete-event simulation modeling process developed in collaboration with DFW Airport to assess aircraft assignment strategies to deicing pad locations by monitoring impact on DO. Our process consists of the following phases: (1) Data Collection, (2) Probability Distribution Modeling, and (3) State Transition Modeling. Both Phases (2) and (3) utilized data mining approaches, including treed regression and variable selection via false discovery rate. Detailed implementation of these phases is described for the DFW Airport case study, and the DFW Airport deicing activities simulation tool framework is presented. The actual data and simulation results were compared in terms of the DO levels in airport receiving waterways to verify the model validity after implementing the proposed model for DFW. Thus, the proposed model can be implemented by airports to control and minimize the adverse environmental effects resulting from deicing activities by optimizing the aircraft assignment to the pad locations.

Identification of physically fatiguing tasks performed during aircraft open-basket ground de-icing activities.

Airplane de-icing technicians work from either an open-basket or closed-basket. The objective of this study is to identify the tasks that have an influence on the physical fatigue of open-basket aircraft de-icing technicians. In a Canadian airport during the winter of 2016-2017, a field study was conducted in which the heart rate of 12 volunteer participants was collected. The data was analyzed along with the 22 tasks that make up the activity of open-basket aircraft de-icing. For each participant, the mean absolute cardiac cost per task was compared. The evolution of the cardiac signal based on the resting heart rate and steady state limit was also characterized. According to the cumulative results fatigue occurs for periodic tasks as well as double tasks. More precisely, the most physically fatiguing tasks are spraying de-icing and anti-icing fluids, moving the basket and truck, as well as tactile control and de-icing quality control at ground level. Similar studies would need to be conducted in other aircraft de-icing facilities to improve the generalization of the results.

Comparison of different Parameters of Heart Rate Frequency of Tasks Performed during Aircraft Open-Basket Ground Deicing Activities

Plane deicing is mandatory to insure safe plane take-off. Previous human factors studies have shown that open-basket deicing activity can be improved. The objective of the paper is to compare heart rate assessment models within a field study with numerous influencing variables and small sample size as well as to deepen our understanding of the most demanding openbasket tasks using cardiac output. A field study in a Canadian centered plane deicing facility was conducted in 2016-2017. 12 participants contributed to a thorough description and analysis of open-basket deicing activities. Respiratory and cardiac output of these participants was collected using Hexoskin vests. Working heart rate, heart rate reserves as well as calculations of absolute cardiac cost were done. Working heart rate (WHR), Heart Rate Reserve (HRR) and Absolute Cardiac Cost (ACC) do not behave uniformly for the majority of participants. In field studies with a large number of influencing variables on the heart rate, it is usually not sufficient to consider one single evaluation measure like WHR. In the interest of protecting employees, it seems to make sense to use the more cautious measures HRR or ACC as parameters instead of WHR. Superimposed activities (e.g. forced postures and dynamic use of upper body) have a significant effect on heart rate increases. In 8 out of 11 cases we have fatigue-related increases in heart rate over the observation period. Similar studies need to be conducted in other aircraft deicing facilities.

Long-term evaluation of the impact of urbanization on chloride levels in lakes in a temperate region

The application of road salts for winter de-icing of roadways in cold regions has been demonstrated to increase chloride (Cl) concentrations in nearby surface waters and have a negative impact on aquatic organisms and processes. In addition to toxicity to aquatic organisms, high concentrations of Cl in lakes can alter mixing processes, resulting in prolonged anoxic conditions and associated water quality degradation. Elevated concentrations of Cl in freshwater environments in cold regions is a well-documented phenomenon, but few studies have undertaken a long-term evaluation of the impact of urbanization on lakes. In this paper, nine lakes in the Halifax region of Nova Scotia, Canada, were monitored over 35 years to observe Cl concentrations prior to, during, and after urbanizing development. Cl concentrations were observed to increase in most study lakes over the monitoring period and all nine exhibited seasonal trending in response to winter de-icing activities. Six of the lakes achieved a steady-state Cl level after an initial increase in response to development activities, two are potentially still in transition, and one was unaffected by development activities. Watershed land use was found to be a good predictor of the springtime concentration of Cl and can help to inform decision-making surrounding development activities. When the percent of developed land was 25% or more, the Cl concentrations tended to exceed Canadian freshwater quality guidelines for the protection of aquatic life.

Considerations on Aircraft On-Ground De-Icing and Sustainable Airport Development

On-ground de-icing activity represents a need to protect the aircraft under low-temperature operating conditions, with a high degree of saturation of suspended water vapor or in precipitation conditions that may favor depositions on aircraft surfaces. This activity determines the use of de-icing and anti-icing agents in significant quantities, which leads to compliance with environmental protection standards. In this paper the authors identify solutions for the management of the residues resulting from de-icing activities that lead to soil contamination with different chemical compounds from the fluids used for de-icing.

Data-driven optimization for Dallas Fort Worth International Airport deicing activities

Airplane deicing is a safety measure to eliminate/prevent icing on airplanes that can lead to airflow disruption and emergency conditions. Aircraft deicing/anti-icing fluids (ADF) are high in glycol content. At Dallas Fort Worth International Airport (DFW), the major aircraft deicing activities are conducted at designated deicing pads called Source Isolation Deicing Sites, where ADF run-off can be captured and conveyed into the airport’s glycol collection system. A portion of ADF drips from the aircraft during taxiing and shears off the aircraft during take-off, entering nearby waterways without treatment. Glycol acts as a nutrient for bacteria in the airport’s receiving waterways, resulting in an increase in bacterial growth and a subsequent reduction in dissolved oxygen (DO), potentially endangering aquatic life. This paper proposes a prototype data-driven deicing activities management framework for DFW to address the complexity of airport deicing operations and its impacts. The proposed framework uses stochastic dynamic programming (SDP) to assign airplanes in each hour to deicing pad locations, so as to maximize DO in the receiving waters, subject to airport constraints. Some data were artificially generated using the available knowledge of airport operations. The state transition equations in SDP were estimated. The proposed framework was demonstrated using three cases during major deicing events. Improvements in DO compared with actual DO recorded in the data were mixed; however, the results motivated DFW to implement a new data collection process to replace the artificially-generated data, so that a more accurate optimization could be conducted in the future.

Ergonomic Time and Motion Studies of Aircraft De-icing Work

This paper reports results of time and motion studies and ergonomic consequences of aircraft de-icing work. De-icing of aircraft on the ground is extremely important for maximizing technical safety, but also a major challenge for persons performing it. Between December 2016 and March 2017 we carried out video-supported time and motion studies on 11 personnel performing de-icing work in open baskets at a Canadian airport. Total time analyzed was 788 min, during which 1192 individual observations were made. Our observation sessions varied in length from 59 to 96 min, partly for weather reasons. After ascertaining the work systems used by the de-icers and determining the principal factors influencing them, we used REFA methods to perform a hierarchical analysis of work activities. Energy turnovers generated by these activities were calculated. These lie between 4 and 13 kJ/min, depending on weather conditions, air traffic density and individual work patterns of the de-icing personnel. Contributions of the individual activities to total value added were classified. Roughly one third of the de-icing activities made a direct contribution. The remaining two thirds made only indirect contributions or none at all. Stresses arising from the work were compared with the few findings reported in the literature. Further investigations are needed to understand thoroughly centralized de-icing activities.

Data mining modeling on the environmental impact of airport deicing activities

This paper presents a statistical analysis on the environmental impact of airport deicing activities at Dallas-Fort Worth (D/FW) International Airport. The focus of this paper is on aircraft deicing, which typically uses a spray of aircraft deicing and anti-icing fluids (ADAF). ADAF has a high concentration of ethylene/propylene/diethylene glycol, which shears off airfoil surfaces during takeoff and drips to the runways during taxiing. A significant portion of the glycol runs off and mixes with the airport’s receiving waters during heavy deicing periods, resulting in bacterial growth that causes an increase in chemical oxygen demand (COD) and a subsequent reduction in dissolved oxygen (DO) in the receiving waters. In this study, statistical methods for data mining were employed to evaluate the impact of airport deicing activities on COD and DO in the receiving waters immediately surrounding D/FW Airport. In particular, decision tree models were developed to determine important explanatory variables for predicting levels of COD and DO in the airport’s waterways. The decision tree modeling and analysis of COD determined north–south wind, glycol usage at a specific deicing pad, and monitoring site to be significant explanatory variables. The impact of glycol usage on DO was apparent as every decision tree at least one group with a median DO below 4.0 mg/l, and these low-DO groups were associated with high glycol usage. These results are crucial to D/FW Airport in their goal to minimize the potential adverse impact of deicing activities on the water quality in waterways proximate to the airport. The advantages of data-driven modeling and analysis are its cost-effectiveness due to its potential to be implemented without making major changes in physical systems, ease of application, and usefulness in making future management decisions.

Photochemical Degradation of Benzotriazole

Benzotriazole is a commonly used additive in aircraft de-icing fluids. As a result of extensive de-icing activities the compound is detected in the groundwater below de-icing platforms at several international airports. The compound is toxic, and not biodegradable. Laboratory tests have been performed to study if UV irradiation can degrade the compound and reduce the aquatic toxicity. Benzotriazole can be degraded by UV irradiation at pH values below 7. Approximately 65% reduction in the benzotriazole concentration was achieved at a dose of 320 mWs/cm2, and almost 90% reduction was achieved at 1070 mWs/cm2, with an apparent first order relation between the logarithm to the UV dose and the reduction. Benzotriazole is not significantly mineralised by UV irradiation, but transformed into other compounds, of which aniline and phenazine were identified. The metabolites show toxic effects, but they are not as toxic as benzotriazole, resulting in a general decrease in toxicity as a result of UV irradiation.

Highway Deicing Salt Runoff Events and Major Ion Concentrations along a Small Urban Stream

ABSTRACT Highway deicing activities can influence the quality of waters draining urban areas that experience multiple winter season freeze/thaw cycles. However, because of the flashy hydrology of smaller urban streams, and the unpredictable nature of deicing runoff, these events are difficult to fully document by traditional monitoring approaches. The frequency, duration, intensity and downstream attenuation of highway deicing salt runoff events were captured by remote continuous flow and conductivity monitoring, in combination with dry and wet weather grab sampling, at four stations along a three-kilometer-long unculverted reach of an urban Pennsylvania stream, Nine Mile Run.

Aircraft icing

Aircraft icing

Detection of Aircraft Deicing/Antiicing Fluid Additives in a Perched Water Monitoring Well at an International Airport

Tolyltriazoles have recently been shown to be the primary agents in aircraft deicing/antiicing fluids (ADAFs) responsible for acute Microtox activity. However, little is known about the fate and effect of these compounds in the environment resulting from airport deicing activities. This research communication describes the first evidence that constituents within ADAFs, other than glycols, are present in subsurface water samples from a major North American airport at environmentally significant concentrations. These concentrations are approximately 25 times higher than the reported EC50 values in Microtox assays.

Modeling Sodium and Chloride in Surface Streams During Base Flows

Sodium and chloride contamination of shallow groundwater can be frequently attributed to three major sources: (1) Individual sewage disposal systems (ISDS); (2) road salt application during winter deicing activities; and/or (3) road salt storage. Effluent streams in a large reservoir watershed were sampled during baseflow conditions. Sodium and chloride concentrations were regressed against different land use types including roadway, residential, commercial, industrial, agricultural, and forest areas. Results indicate that roadway areas are the largest single influence of sodium and chloride concentrations. Data from other watersheds are compared to the developed relationships and agreement is favorable. Additionally, a mass balance is performed and indicates that, typically, roadway deicing activity in the test watershed can potentially introduce far greater amounts of sodium and chloride in the local groundwater than the next greatest influence, residential septic systems.