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To minimize fuel burn, noise, and environmental impact, novel technologies to move aircraft from gate-to-runway and runway-to-gate will be introduced. Rather than changing flight procedures, due to their comparative rigidity, airlines will more likely adopt integrated ground propulsion as a method of saving time and fuel. Of the multiple mechanisms of IGP studied, on-board systems produce the greatest reduction in emissions and the best cost-efficiency, while external systems reduce fuel burn at the cost of increased NOx emissions. Electric systems could also be adopted to enhance the process.
One concept is for tugs to be replaced by an APU powered motor-generators that drive the associated aircraft wheels. Another concept is for tugs to bring aircraft all the way from the gate to the runway. WheelTug is a fully integrated ground propulsion system for aircraft which puts a high torque electric motor into the hub of the nose wheel to allow for backwards movement without the use of pushback tugs and to allow for forward movement without using the aircraft’s engines. WheelTug will drive the aircraft with power supplied by the onboard APU (Auxiliary Power Unit). The first version was designed for the Boeing 737NG.
One recent design proposes an integrated vehicle dynamics control, or IVDC, algorithm. This system would use nonsingular fast terminal sliding mode (NFTSM) to coordinate active front steering and direct yaw movement, enhancing handling and providing vehicle stability. A non-automated system in the works at NASA involves turboprop technology. The SCEPTOR X-Plane, built with fold-out propellers and wingtip vortex propeller integration, is currently in the testing phase, with test flights scheduled to run until 2018. The goal is to increase propeller efficiency from 28% to 92%, while reducing noise by 15 dB on average.
Enhanced ground propulsion systems will have economic impacts as well as safety impacts. Data from WheelTug, presented at the IATA Singapore Conference in 2017, indicates that airline profitability is inversely correlated with aircraft ground time. The effect is consistent across multiple airlines in multiple nations.

Potential hazard

  1. Runway incursions
  2. Ineffective new pilot interfaces
  3. Inadequate visibility from the flight deck
  4. Failure to complete engine run-up and checklists
  5. Damage to nose gear due to frequent coupling/uncoupling with propulsive tugs (for both towbar and no-towbar, wheel capture approaches)

Corroborating sources and comments


2014 – The Green Trajectory of an Aircraft Aided During Take-off by Ground-Based System Using Magnetic Levitation Technology:

Very high air traffic density in the largest airports and in their vicinity involves that the air traffic in the largest airports and their areas of operations approaches the capacity limits. Such high density of the air traffic adversely influences the natural environment in the vicinity of the airports due to the increasing cumulative noise level and the concentration of environmentally hazardous substances. The increased air traffic density in the airports and their vicinity has also a significant impact on decreasing the flight safety level, especially during approach and landing operations. One of the possibilities to improve the situation is to work out innovative solutions aimed at decreasing the aircraft pollution and improving the transport effectiveness. There are several technologies that could be applied to reduce the harmful influence of the air transport on the environment. Novel ideas include for example operation of the aircraft without the conventional undercarriage system and using the ground based power and supporting systems for takeoffs and landings. If ground launched technologies that accelerate and “launch” the aircraft into the air are applied, than the power requirements can be substantially reduced even over the initial climb phase, as only such power would be needed that is required to maneuver and fly. One of the major concepts is using magnetic levitation (MAGLEV) technology to support aircraft take-off and landing. In case of using the magnetic levitation technology, the airframe weight can be considerably reduced, since the undercarriage system could be lighter or even ignored. The required engine power is determined by the takeoff phase in which a substantial thrust is needed. Therefore, if the aircraft could takeoff and start the initial climb phase with the ground power, the installed power may be reduced, resulting in less weight, less drag and less overall fuel consumption that leads to emission reduction. These advantages, the lower fuel consumption and emissions, increase sustainability of the transportation system. Different conditions of the takeoff give possibilities to shape the trajectory of the initial stage of the aircraft accent after the takeoff in order to decrease the negative influence on the environment. The aim of the present work was to determine the optimal conditions of the takeoff and the optimal trajectory of the initial accent of the aircraft aided in the phase of the take off by the system using the MAGLEV technology, minimizing the fuel consumption and noise emission. The simplified algorithm of optimization of the flight trajectory was used in this work; it uses the method of approximation of the flight path by the third degree polynomial.

Europe Flight Path 2050 document considers ZERO emission for aircraft ground operations as a goal. These new technologies have to be developed.

EGTS (ELECTRIC GREEN TAXIING SYSTEM); (Data from WheelTug indicating that airline profitability is inversely correlated with ground time. Mentions presentation of technology at IATA Singapore Conference on May 23-May 24.) (Considers integrated ground propulsion as a way to save fuel in lieu of changing flight procedures, due to their comparative rigidity. The study compares conventional, single-engine on, external, and on-board systems and their environmental impacts. On-board has the best emissions reduction, while external burns less fuel, but increases NOx admissions. On-board is also said to be the best in terms of cost-efficiency.) (Describes an in-development IVDC [integrated vehicle dynamics control] algorithm using nonsingular fast terminal sliding mode (NFTSM) to coordinate active front steering and direct yaw moment control. AFS provides handling enhancement, with other systems providing stability upon reaching its limit.) (Turboprop vehicles considered to facilitate propulsion and reduce emissions. SCEPTOR X-Plane, built with fold-out propellers and wingtip vortex propeller integration, is being tested for airworthiness, with test flights to run through 2018. The goal is to increase propeller efficiency from 28% to 92%, while reducing noise and improving flight quality. Connected to HEIST technology.)

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