Frequently Asked Questions (FAQ)


What aircraft platforms are targeted for the GTS (Green Taxi System)?

The GTS system is capable of being installed on any aircraft or helicopter that has an APU (Auxiliary Power Unit) installed. The system has been demonstrated on the Airbus A320 narrow body aircraft.

Are the aircraft original equipment manufacturers involved with the project?

Yes, Airbus has provided a No Technical Objection (NTO) for the GTS on the Airbus A320 and another large OEM has provided use of their extensive system patent.

How long is the development cycle?

Development of the FAA conforming prototype system is expected to take about 12-18 months from customer launch.
How long to get certified?

How long to get certified?

After prototype completion, approximately 12 months is required to complete FAA Supplemental Type Certificate (STC) certification.

What are the certification plans for the system in multiple other countries?

The system will also be designed to EASA European Authority for Aviation Safety) standards and the EASA approval based upon the US FAA STC approval. GTS will work closely with the regulatory authorities in other countries to achieve operational approval of the system based upon our customer’s requirements.

With all the system benefits, why is it not in use already?

The original system was developed and prototyped by the team of Honeywell, L3 and Safran. Due to falling fuel prices in 2015, competitive complications within the companies, final system production was not achieved. Many very interested parties were more than a little disappointed in the outcome and have encouraged GTS to continue towards production. The current team consists of former Honeywell and L3 team members who were/are committed to seeing the industry changing system come to completion.


What is the return on investment for the system?

The system purchase price will have an internal rate of return (IRR) in excess of 40% per year from the 4-12% fuel savings, 2-3X extended brake life, elimination of ground tug equipment, quicker aircraft turn times and possible carbon credits.

What are the Brake savings? 

It is expected that the brake savings utilizing the GTS system will reduce brake wear by over 50% therefore increasing the life cycle of carbon brakes by 2-3 times more cycles before brake replacement/refurbishment is required.

What is the cost of carrying the system per year per aircraft?

The amount of extra fuel required to carry the system weight of 200 lbs for one year per aircraft ranges from $4,000 to $12,000 per year depending on the type of aircraft, flight hours and types of routes flown. The cost to carry will be approximately 3% of the total financial savings the system provides.

How much does the system save in aircraft costs?

The system saves $300,000 to $500,000 per year per aircraft between fuel, brake wear, tug, and latency time savings in addition to its environmental benefits. See the “More Information” section of our website.

How much does the system save in emissions?

The system saves over 1987.3 Kg (4,381.2 Lbs) of CO Savings Per Aircraft Per Year.

Does the system provide benefits for military aircraft?

Yes, aircraft like the C-17 or the C-130 are often parked close to each other to assist with security often in unimproved environments. Starting the engines to taxi out can blow sand and dirt into the engines/system of aircraft parked close by and the GTS system avoids this issue. Also, tactical advantages due the low noise signature and elimination of FOD (Foreign Object Damage) engine damage increases operational readiness and tactical surprise of military aircraft.

What about helicopters?

Yes. The GTI system installed on a helicopter avoids the need for main rotors turning to taxi the aircraft eliminating the dangers to buildings, personnel and other aircraft along with a lower noise signature.


Is the Green Taxi System part of the aircraft Minimum Equipment List (MEL) and required to be operational for aircraft use? 

The GTS system is not required to be operational for aircraft use and is not an MEL item. The system totally disengaged from the aircraft when not in use or if the system not operational. If the system is disengaged or not operational the aircraft can be taxied with the main engines.

Does the Green Taxi System require special pilot training? 

The pilot steers the aircraft using the existing tiller nosewheel steering system along with the use of aircraft brakes if required. The GTI system allows for more precise speed control compared to using the main engines. An operational check out using Level A pilot training with video training and line check operational training may be used.  No simulator training is required.

Can the system be used for movement of the aircraft by maintenance crew without needing a pilot?

Yes, the system is easy to use and ground maintenance crew can be trained to use the system to move aircraft as required without needing to have a pilot on board.

What is the expected operational life of the system?

The design of the GTS is extremely robust and is expected to last the life of the aircraft in operation. The system components are designed and built to hybrid systems standards utilized on heavy truck, tank, and naval hybrid drive systems.

How many hours does it take to install the system?

The system is designed to be easily installed during aircraft build and/or retrofitting to existing aircraft during nominal C checks in two or three overnights (150 man-hours). If more time is required, it can be integrated into a heavy maintenance D check if necessary.

What are the expected maintenance costs and system reliability?

The DC motors used by GTS are extremely reliable and have very long expected life with minimal maintenance similar to electric vehicles. However, since the system is moves the aircraft a relatively short distance in comparison to electric vehicles the electric motors should last the life of the aircraft with periodic inspections. Minimal maintenance can be accomplished during routine phase inspections. The ongoing operational maintenance cost of the Green Taxi system should be less than 5% of the Green Taxi aircraft savings per year.

How is the system used to back the aircraft away from the gate?

The flight crew simply activates the system in reverse mode with wing-walkers to ensure safety and can then back the aircraft away from the gate and turn in the required direction using normal aircraft steering. Speed of reverse is limited to 5 kts.

Has an approved FAA standard operating procedure (SOP) been developed for the system?

The system will leverage SOP development is in process with the help of the GTI Airline Working Group consisting of members of the interested airlines.

Can the system be used to dynamically brake the aircraft during system operation?

Yes, when the main aircraft engine(s) are turned off the system provides dynamic braking and does not require the pilot to utilized the main aircraft wheel brakes. This reduces/eliminates the brake wear caused by the pilot frequently needing to use aircraft landing gear wheel braking due to the excess thrust provided by the main engines. during taxi operations. When the main aircraft engine(s) are operating the system is not operational and therefore does not provide dynamic braking.

Will the system decrease the taxi speed of the aircraft?

No, The GTS will allow taxi speeds up to 25 kts, which is the maximum allowable taxi speeds at most airports around the world. The average taxi speed may be faster than with existing taxi operations as the pilot will not need to brake to slow the aircraft down due to excess thrust from the main engines. It should also allow for a smoother taxi ride
for passengers.

Will the pilot have an indication that the system is disconnected from the landing gear?

Yes. A light on the flight deck system controller will notify that the system is disconnected or if the system has any malfunctions.for passengers.

Can the system be used in snow and icy conditions?

Yes, however for icy uphill taxiways, the main engines can and should be used to avoid slippage and steering difficulties.

Will the system affect APU (Auxiliary Powe Unit) life?

No, for most airlines the APU is operated during most of the taxi time already and is running at 100% of rated RPM so no reduction of APU life.

Can the GreenTaxi system be used while the main aircraft engines are operating?

Yes, we expect the GreenTaxi eTaxi system to be able to be used while the engines are operating. The key design criteria will for us to use “regenerative braking” whereby we put the braking energy back into the aircraft electrical system as conditioned AC power similar to the way the starter/generators work on turbine engines. If we can get this certified with the FAA/EASA we can provide braking at all times with the aircraft engines operating. If we cannot input the regenerated energy in the aircraft electrical system we can still provide braking with the engines operating but it may be more limited as we would need to put this excess electrical energy back into aviation grade ballast resisters which will heat up if the braking is done repeatedly. For dynamic braking the pilot simply moves the joystick to the “reverse” position to modulate the degree of dynamic braking they desire while the main engines are operating.


How much does the Green Taxi System weigh? 

200 lbs (90 KG) net weight for the system. In some aircraft nose ballast can be removed so the installed weight may be less.

How much weight does the Green Taxi System place on the landing gear itself? 

60-75% of the total weight is carried on the landing gear itself. The remainder is in the aircraft electronics bay and on the flight deck.

How will the system disconnect from the landing gear when not in operation?needing a pilot?

The system will have a failsafe disconnect in the event of detection of any system failure, when the aircraft is in flight and if ground speeds are in excess of 25 knots.

Can a tow tug still be used with the GTI system installed?

Yes. The design of the GTI system and installation does now interfere with the tow tug
attachments on the aircraft nose gear.

Should the system be inspected before every flight?

The GTI system should form part of the pilot’s inspection prior to each flight.