FUTURE OF DEICING TECHNOLOGY

INFRARED DEICING SYSTEMS

Infrared (IR) deicing technology involves melting frost, ice, and snow from aircraft surface with infrared energy. IR energy systems are based on natural gas- or propane-fired emitters that are used to melt frost, ice, and snow. Infrared energy does not heat up the surrounding air and tests have shown that it has negligible effect on the aircraft cabin temperature.

Two main manufacturers are leading the way in developing infrared-based De-icing systems: Radiant Energy Corporation with the InfraTek™ system and Infra-Red Technologies with the Ice Cat™ system. The Ice Cat™ system uses IR emitters fueled by natural gas or propane mounted on booms that are fitted to specially designed trucks. The booms are then positioned above the aircraft surface and the IR emitters are used to remove frost, ice, and snow. Currently there is no commercial application of this system.

The InfraTek™ system consists of infrared generators, called Energy Processing Units (EPUs), located in an open-ended, hangar-type structure. The EPUs are fueled by natural gas and generate IR energy waves to melt and evaporate frost, ice, and snow. If the aircraft surface is dry, the IR waves are reflected away.

The InfraTek™ system is designed to be operated by only one person and is mainly controlled by a computer. Before deicing can begin, the floor of the InfraTek™ system facility is heated in order to facilitate the deicing process of aircraft lower parts such as the landing gear. Depending on the type of aircraft and the severity of ice and snow build up, the energy and wavelength generated by the EPUs are adjusted. In March of 1996, InfraTek™ technology was shown to deice a Boeing 727 in six minutes, which is about the same amount of time it would take to achieve deicing results using conventional ADFs .

There are currently three InfraTek™ Deicing System facilities in the US and one in Oslo, Norway. The largest by volume is the one installed at JFK International Airport in March 2006. The facility was operating during the 2006-2007 deicing season. The system is designed to provide deicing services for up to a 747-300 size aircraft. The following performance benefits have been documented:

§ Approximately 90% reduction of glycol use per aircraft under snow and ice conditions.

§ No glycol use for defrosting operations.

Furthermore, in terms of budget management, using the InfraTek™ system allows more accurate winter operations budgets for customers since the system charges a fixed fee based on the size of the aircraft. Conventional deicing methods are priced based on the volume of fluid applied, which varies based on the severity of winter weather conditions. However, cost data is currently limited by the number and scale of facilities using the InfraTek™ system.

IMPLEMENTATION ISSUES

Although IR energy systems have been in development since the mid-1990s, their use is not yet widespread. A few things to consider over their implementation are:

§ The physical size of systems such as InfraTek™ makes planning and design for such a system quite complex. Certain airports might not be able to accommodate such a facility as the structure needs to conform to FAA part 77 – Objects Affecting Navigable Airspace.

§ Due to the aircraft processing capacity of an InfraTek™ type system, an IR facility can present a bottleneck during peak traffic hours. Traffic analysis is crucial for airports looking to adopt an IR system.

§ While IR systems reduce the need for ADFs, thus limiting the environmental impact from these fluids, the system cannot provide anti-icing protection. Some anti-icing fluid use is still required to provide holdover times and so is the collection and containment of these fluids.

§ The JFK InfraTek™ facility is reported to have cost $9.5 million. With such infrastructure costs, there needs to be a commitment by airlines to make use of the facility.

REGULATORY ISSUES

The FAA has put out several guidelines and recommendations for ground deicing using IR energy. In particular, AC 120-89 allows IR energy use to deice aircrafts to be part of certificate holder’s deicing program. The FAA also published AC 150/5300- 14, Change 2 to the Design of Aircraft Deicing Facilities to include IR facility guidelines.As IR energy deicing technology continues to develop and spread, environmental concerns over this new system will need to be considered. For instance, what is the necessary power generation used by the IR emitters and do they have possible adverse effects. Also considered should be the air emissions by aircrafts moving to and from the IR deicing facility. Answers to these questions should be answered though studies performed at the local airport level.

TEMPERED STEAM TECHNOLOGY

Tempered Steam Technology (TST) uses a mix of air and water vapor steam infused air to melt ice on aircraft surface and then plain hot air to dry the surface. The system also includes an inflated blanket type device that is affixed to a vehicle boom to ensure that the heat is contained. Several tests have been conducted during the 2006- 2007 deicing season. The new device demonstrated the ability to deice and dry up to 6 cm of snow and up to 2 cm of ice in about 10 minutes [20]. TST can thus prove to be useful for frost removal and pre-deicing applications, potentially reducing the volume of Type I ADF needed to deice an aircraft.

UNDER DEVELOPMENT TECHNOLOGY

There are a few deicing technology that is currently under development.

 Polaris Thermal Energy Systems, Inc has been evaluating warm fuel as a deicing method. If the wing fuel tanks are infuse with heated fuel, frost, ice, and snow will not form on the aircraft wing surface. This will reduce the amount of ADF needed to deice the aircraft.

 At the Dartmouth's Thayer School of Engineering, Dr. Victor Petrenko is working on pulse electro-thermal deicing. This method uses short pulses of electricity to break up the ice.

 Foster-Miller, Inc. is trying to develop technology that will provide anti-icing protection by coating the aircraft surface. This surface treatment will not require ADF usage.

IMPROVED WEATHER FORECASTING

Weather forecasting plays a crucial role in optimizing aircraft deicing operations. Real-time forecasting assists airport operators in making accurate decisions on deicing applications. Manpower and money is wasted if more resources than necessary are devoted to deicing operations due to inaccurate forecasts. Improved technology in weather forecasting has been in development. One such system is the Weather Support to De-icing Decision Making (WSDDM) developed at the National Center for Atmospheric Research (NCAR). The WSDDM system includes sensors that measure temperature, atmospheric pressure, dew point, and wind speed and direction as well as snow gauge that measures the liquid equivalent of snowfall. The data is outputted by an integrated display system that requires minimal training to operate. The use of WSDDM system is also beneficial in determining accurate holdover times as it is able to determine the type of precipitation occurring at any moment and its liquid equivalent value. The system can calculate the time it will take before a particular ADF will fail in real-time under existing conditions.

The WSDDM system was developed with the support of the FAA. In AC 150/5200-30C, Airport Winter Safety and Operations, the FAA recommends airport operators to adopt WSDDM type systems. The system complies with equipment performance and installation requirements provided by the SAE Aerospace Standard AS #5537.

CONCLUSIONS

The process of aircraft deicing is a vital part in not just aircraft safety but in airport design and management as well. To draw from the design of Denver International Airport (DIA), the facility manager there for Inland Technologies' glycol recovery and recycling plant once said, "They built the deicing system first, and then basically build the airport around it". This is to show that deciding on and installing a new deicing system is quite complex, especially with the expansion of various new technologies and environmental regulations. At this stage, it looks like no technology can escape at least some ADF usage, meaning that airports will always need to contain the environmental impact of these fluids. Does it make more sense for airports to invest and change their systems to accommodate new deicing technology that uses less ADFs or to invest in advancing new glycol collection and recycling systems? It seems that particularly major airports will not be able to avoid large capital expenditure associated with deicing operations.