Electric Green Taxiing: Revolutionising Airport Ground Ops

Imagine an airport runway, not filled with the deafening roar of jet engines during taxiing, but with a quiet, almost serene hum. For decades, the process of moving large aircraft across the tarmac, from gate to runway and vice versa, has relied on their powerful main engines or cumbersome tugs. This essential, yet often inefficient, phase of flight consumes significant amounts of fuel and contributes heavily to noise and air pollution around airports. However, a revolutionary concept known as the Electric Green Taxiing System (EGTS) promises to transform this aspect of aviation, heralding a new era of sustainability and operational efficiency for airlines worldwide.

What Exactly is an Electric Green Taxiing System (EGTS)?

At its core, an Electric Green Taxiing System (EGTS) is an innovative electric taxiing solution designed to allow aircraft to manoeuvre on the ground without needing to engage their main engines or rely on external pushback tractors. Its primary objective is clear: to drastically reduce the volume of fuel consumed by aircraft during ground operations and, consequently, to cut down greenhouse gas emissions. The EGTS technology enables an aircraft to taxi autonomously under its own electrical power, drawing energy from the Auxiliary Power Unit (APU) generator, a smaller engine onboard that typically provides power for lights, air conditioning, and avionics when the main engines are off. This system is specifically engineered for single-aisle aircraft, such as the widely used Airbus A320 family and the Boeing 737 series, which constitute a significant portion of global airline fleets.

The Ingenious Design Behind Electric Taxiing

The mechanics of the EGTS are both sophisticated and practical. The system works by equipping each of the aircraft's two main landing gear inboard wheels with an electric motor. These motors are powered directly by the aircraft's Auxiliary Power Unit (APU) generator. This ingenious setup allows the aircraft to push back from the gate without the need for an airport tug, and crucially, to taxi across the airfield without firing up its main engines. This capability represents a monumental shift from traditional methods, where jet engines, optimised for flight, operate inefficiently and consume vast amounts of fuel at low speeds on the ground.

Pilots control the EGTS through an electronic Pilot Interface Unit, which allows them to select the desired speed and direction – forward or reverse – for ground movement. These commands are then interpreted by the Wheel Actuator Controller Unit (WACU), which ensures the appropriate and proportional torque is delivered to each driven wheel. The system, weighing approximately 300 kilograms (660 lb), is permanently installed on the aircraft, making it an integral part of its operational capabilities. It is designed to facilitate taxiing speeds of up to 20 knots (approximately 37 km/h or 23 mph), providing ample speed for efficient ground movement. For the integrated EGTS developed by Safran, a 50 kW (67 hp) motor within the main landing gear wheels contributes to an impressive 4% reduction in fuel burn over an entire flight cycle, a significant saving for any airline.

A Journey Through Innovation: The Development Story of EGTS

The concept of electric taxiing isn't entirely new, with a patent for such a system applied for by Delos Aerospace as early as 2003 and published in 2006. However, the most significant push for the EGTS came with the joint venture established by two aerospace giants, Honeywell and SAFRAN, who announced their collaboration, EGTS International, at the Paris Air Show in 2011. This partnership brought together Safran's extensive experience in integrated landing gear systems with Honeywell's renowned heritage in APU innovation, creating a formidable team to tackle this complex engineering challenge.

The development journey saw several key milestones. In 2012, easyJet, a prominent European airline, became the first carrier to publicly support the development and trial of the EGTS, signalling strong industry interest. Following initial ground testing and the system's first movement in April 2013, the EGTS was publicly demonstrated at the Paris Air Show in the same year, showcasing an Airbus A320 taxiing with its engine covers on, a powerful visual testament to its capabilities. Air France also announced its support in June 2013, further validating the concept. Towards the end of 2013, Airbus itself signed a Memorandum of Understanding (MoU) with EGTS International to further develop and evaluate the system for its highly popular A320 Family.

The momentum continued into 2014, with Honeywell and Safran signing an MoU with Indian airline GoAir to test the system and provide crucial operational data to potential customers, helping to project accurate fuel savings. Mexican airline Interjet followed suit, becoming the first North American airline to support the advancement of the EGTS. However, the path was not without its challenges. By July 2016, amidst a period of low oil prices that somewhat sapped the market demand for fuel-saving technologies, Honeywell terminated its joint venture with Safran. Despite this setback, Safran demonstrated its commitment to the technology, continuing to work on electric taxiing systems, though the A320 demonstrator from 2013 was decommissioned. By 2017, Airbus had authorised the marketing of the system on the A320, but ultimately left the programme in 2019. Resiliently, by 2022, Safran was reportedly designing an even more integrated, lighter system as original equipment for new aircraft programmes, indicating a long-term vision for its adoption.

The Unmistakable Advantages: Why Electric Taxiing is a Game-Changer

The benefits of an Electric Green Taxiing System are multifaceted, impacting operational costs, environmental footprint, and overall efficiency:

• Significant Fuel Reduction: By eliminating the need to use main jet engines for ground movement, airlines can achieve substantial fuel savings. Jet engines are notoriously inefficient at low speeds and consume a disproportionate amount of fuel during taxiing compared to their flight operations. The reported 4% fuel burn reduction over an entire flight cycle, thanks to the 50 kW motor in Safran's integrated EGTS, translates into millions of pounds saved annually for large airlines.
• Reduced Operating Costs: Beyond fuel, the EGTS minimises the wear and tear on expensive main engines, extending their lifespan and reducing maintenance requirements. Furthermore, it eliminates the cost and dependence on the availability of airport tugs, which require their own fuel, maintenance, and personnel.
• Environmental Benefits: This is where the "Green" in EGTS truly shines. Slashing carbon and other noxious emissions (like nitrogen oxides and unburnt hydrocarbons) during ground operations contributes significantly to cleaner air around airports and helps airlines meet increasingly stringent environmental regulations. It also drastically reduces noise pollution on the tarmac, improving conditions for ground crew and airport communities. This aligns perfectly with global sustainability goals.
• Enhanced Operational Efficiency: The system can reduce Foreign Object Damage (FOD), which occurs when jet blast from powerful engines stirs up debris on the tarmac. By allowing aircraft to move independently, it can also potentially improve turnaround times and provide greater flexibility for aircraft movement, reducing congestion at busy gates.

The combined experience and expertise of Safran and Honeywell in the initial development phase presented a compelling proposition, creating a viable and credible electric taxiing solution for the next generation of single-aisle aircraft.

Navigating the Market: Competitors and Alternatives

While EGTS represents a cutting-edge on-board solution, it is not alone in the quest to revolutionise aircraft ground operations. Several other systems, with varying approaches, are either operational or under development:

Taxibot stands out as the only certified and currently operational alternative taxiing system in the market. It is a semi-robotic tractor that meets the aircraft for both taxi-in and taxi-out, connecting to the aircraft and then being controlled by the pilot. This approach keeps the aircraft's engines off without permanent on-board modifications to the landing gear itself.

Competing on-board products include WheelTug, which takes a different approach by installing its drive motors within the aircraft's nose gear. As of May 2024, WheelTug reported being well on its way towards US FAA certification, with commercial operations targeted for early 2026.

Another notable, albeit unsuccessful, competitor was L-3 Communications' eTaxi system. Trialled in 2011 on an A320 non-flyable demonstrator in collaboration with Lufthansa Technik, it proposed a similar main landing gear electric taxiing system to EGTS. However, L-3 Communications abandoned its plans in 2013, citing high investment costs.

Is Electric Taxiing Truly a Viable Solution for Modern Aviation?

Based on the extensive development, trials, and the clear benefits it offers, the electric taxiing system stands as a highly viable solution for achieving lower costs and greener operations in the aviation industry. Despite the challenges faced during its development, including partnership changes and market fluctuations, the core proposition remains incredibly strong. Electric taxiing can profoundly improve airlines' operational efficiency by delivering tangible reductions in fuel consumption, eliminating pushback and taxi-related costs, and providing significant environmental benefits by slashing carbon and other harmful emissions generated during ground operations. As the aviation industry strives for greater sustainability and cost-effectiveness, technologies like EGTS represent a crucial step towards a more responsible and efficient future.

The Quiet Revolution: A Look to the Future

The journey of electric taxiing, from early patents to sophisticated prototypes and ongoing development, underscores a persistent drive within the aerospace industry for greater efficiency and environmental responsibility. While the initial joint venture between Honeywell and Safran concluded, Safran's continued commitment to designing an integrated, lighter system as original equipment for new aircraft programmes signals a strong belief in the long-term potential of this technology. The vision of quieter, cleaner airports, where aircraft glide silently to and from the runway under their own electric power, is not a distant dream but a tangible future being actively shaped by continued innovation.

Frequently Asked Questions (FAQs)

Q: What types of aircraft is the Electric Green Taxiing System (EGTS) designed for?
A: The EGTS is primarily designed for single-aisle aircraft, such as the Airbus A320 family and the Boeing 737 series.

Q: What powers the EGTS?
A: The Electric Green Taxiing System is powered by the aircraft's Auxiliary Power Unit (APU) generator, a smaller onboard engine that provides electrical power for various systems when the main engines are off.

Q: How fast can an aircraft taxi using EGTS?
A: Aircraft equipped with EGTS can taxi at speeds of up to 20 knots (approximately 37 km/h or 23 mph).

Q: What are the main benefits of using an Electric Green Taxiing System?
A: The key benefits include significant fuel savings, reduced carbon and other harmful emissions, lower operating costs (by eliminating the need for tugs and reducing engine wear), reduced foreign object damage (FOD), and improved operational efficiency on the ground.

Q: Is EGTS currently in widespread use by airlines?
A: While the EGTS has undergone extensive development and demonstrations, including trials with major airlines, it is currently being designed by Safran as an integrated, lighter system for future aircraft programmes rather than being widely retrofitted or standard on existing fleets. Other competing systems like Taxibot are currently operational.

Q: Who were the original developers of the EGTS?
A: The Electric Green Taxiing System was initially developed in a joint venture between Honeywell and Safran, known as EGTS International. While Honeywell later exited the partnership, Safran continues to develop the technology.

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