The Best Towbarless Aircraft Tug: Benefits and Features Sans Towbar
One of the most thankless pieces of machinery on the ramp is the venerable aircraft tug. Paraphrasing the incredible Rodney Dangerfield, they get no respect. They are probably the most utilitarian vehicle in existence. They don’t go farther than maybe a mile or two at a time, but most of the time way less distance than that. They don’t move any faster than the slowest walker on the team (they can go faster, but you get the gist). And basically, they haven’t changed all that much since World War II. They are a lot larger now to accommodate heavier aircraft, and they are all diesel instead of gasoline powered, but the principle is consistent: very heavy, very slow, lots of traction.
Well, the world is changing. Electricity is largely replacing diesel power with conventional tugs, and there is a new, emerging movement on the market: towbarless tugs. Some of these have conventional cabs, but a new movement are completely radio remote control units with no cab or sitting arrangement. Let’s dive in.
Introduction to Aircraft Tugs
Aircraft tugs are used to push aircraft from the gate to the taxiway. This is as old as time itself, or at least commercial flight.
Pushback tugs are specially designed tractors that fit underneath the aircraft and onto the nose gear to move the aircraft. Now, pushback tractors are kind of a misnomer; they certainly work just fine in forward and are used to move aircraft as far as the operator needs them to go. In an MRO setting, this could be as far as across the entire airport. At military airports, this is very common largely because military airfields or air bases are configured completely differently than commercial airports. They are used more as a tow tractor on military airfields, moving aircraft from the ramp to other spots, or to maintenance hangars.
Commercial airports, on the other hand, are made for the efficient and expeditious movement of lots of aircraft all the time. Because of these, there have been a number of tugs designed and made more specifically for pushbacks. These are known as towbarless tugs and they come in a variety of different forms. Most recently, there have been a few examples that are all electric, and even a handful that are remote control electric towbarless tugs.
Conventional tugs use a tow bar that attaches to the nose gear, while newer, more efficient tugs are designed as towbarless tugs. And while these are fine for driving long distances over the airport, they are primarily used for short distance pushbacks. This is a task where the electric towbarless tractor excels. The tractor can be docked and charged every time it isn’t in use, maintaining a high charge.
How Towbarless Aircraft Tugs Work
Towbarless tugs do not use a tow bar, instead lifting the nose landing gear wheels off the ground using hydraulics. On the backside of the towbarless tractors you’ll find a sort of clamp that presses against the backside of the tires, locking them in place.
This saves time and frees up the ramp by removing the complexity of where to store the tow bars, and more importantly, it removes a pivot point in the towing process. The towbarless tractor can turn as tightly as the aircraft can, making sure to not exceed the nose landing gear angle limits which range from 45° all the way to 90°.
Towbarless tractors do not need to be as big as traditional tractors, as the aircraft nose wheel provides the necessary weight and downward force. This is a huge deal, because a conventional tug has to be extremely heavy to function or else the aircraft pushes it all over the place. Not good.
Electric towbarless tugs are more environmentally friendly and can be used in indoor spaces like aircraft hangers. If you have ever run a tug inside a hangar, even with the doors open, you know just how big of a deal this really is. Diesel tugs produce a lot of noxious fumes and it is miserable being in a building with them.
Finally, there is the benefit of no noise pollution. This article is not specifically about electric tugs but that is the direction the industry is moving. Electric tugs are perfectly quiet, which adds a huge margin of safety. Diesel tugs are extremely loud and it is hard to hear commands from the tow team supervisor. From the driver seat, you almost cannot hear anything besides the tug.
Benefits of Towbarless Tugs
There are quite a few benefits to towbarless tractors. So many, in fact, that it is getting hard to consider going back to a standard tug. The most useful scenario for standard tractors would be in an operation where the tractor is being used exclusively for moving aircraft across long distances. Also, some aircraft are simply too large and heavy for a towbarless tug although it is mostly only the largest aircraft out there (B747, A380). Here are a few of the main selling points:
- Increased operator visibility due to the low-profile design of towbarless tugs, eliminating most blind spots.
- Easy maneuverability, allowing towbarless trucks to maneuver into tighter spaces while still being within safe operation limits.
- Optimized control and braking, using hydrostatic regenerative braking as a more effective and efficient way to bring the tug to a stop.
- Reduced risk of accidents and injuries to ground personnel.
- Environmentally friendly, with electric towbarless tugs producing zero emissions.
Safety Features of Aircraft Tugs
Towing aircraft is one of those benign tasks that is also inherently risky. There is no way around it. Thankfully, the tug you use today for towing is much safer than those of yesteryear. First off, the reduction of blind spots is a major factor in this, with clear viewing lanes on most modern tugs.
- Some tugs are equipped with nose gear protection systems to make sure that overtravel is avoided.
- The NPS takes over the operation of aligning the nose wheel in the direction of travel, compensating for the tug’s movements automatically.
- The LiDAR NPS is a more advanced version of the Nose Wheel Protection System, using a 360° high-resolution LiDAR sensor to scan the surroundings and automatically take control of the turntable (for tugs equipped with turntables.
- Collision avoidance, recognizing potential hazards and actively intervening in the towing process.
Not all towbarless tugs are equipped with them, but many have a turntable where the nose landing gear rests. The nose landing gear remains fixed straight ahead but the turntable has 360° of movement, eliminating oversteer completely. Also, in some cases most notably the remote control towbarless tug, the entire tug can go underneath the aircraft fuselage. This creates unparalleled agility in parking and movement. When it comes to parking aircraft in a hangar and optimizing space, nothing has ever worked better than this.
Electric Aircraft Tug: A Sustainable Option
We touched on this a little already, but the electric towbarless tug is becoming a more common sight at airports and airfields all over. An electric towbarless tug is environmentally friendly, producing zero emissions and reducing noise pollution. Emissions are bad enough, but noise pollution is a serious problem on operation ramps.
Electric aircraft tugs are highly suitable for indoor spaces like aircraft hangers, reducing the need for ventilation systems. Lower operating costs, with reduced fuel consumption and lower maintenance costs. Some makes and models are completely sealed units that require no maintenance.
Nose Wheel Tug Applications
A towbarless tug is suitable for almost all applications, including helicopters that operate on wheels rather than skids (although there are a couple of models made specifically for skids). Some of these units go all the way up to 200-tons, so they can handle almost all single-aisle or narrow-body passenger jets, business jets, and a wide range of aircraft, including super-midsize jets, most tactical military jets, and helicopters with single- and twin-tires.
They are also used by FBOs, MROs, corporate flight departments, private owners, and military personnel worldwide. These are particularly handy for military flight operations because it is just one more thing that they don’t have to take with them (the tow bar).
Also, even “universal” tow bars are not necessarily all that universal. For instance, the Boeing 707 tow bar is not compatible with the KC-135, even though they are very similar aircraft. A towbarless tug, on the other hand, is truly universal. The same tug can move an E-3 AWACS and then turn around and move a C-130 or even a C-37 or C-12 Huron. They are the ultimate in versatility.
Operation and Maintenance Cost Savings
There are a few things to think about from the perspective of the end user about why the towbarless tug is such a great option for most flight operations departments, MROs, or FBOs.
- Traditional aircraft tugs have a higher learning curve than towbarless tugs. It takes a lot of effort and experience to get comfortable with a standard tug and towbar.
- However, traditional tugs are easier to fix and less expensive to maintain. Towbarless tugs rely on massive hydraulic pistons and surrounding systems, which break down. A standard tug is really pretty simple.
- An electric tug might have a higher up-front cost but operations and maintenance will be lower in the long run.
The Future of Aircraft Tugs: TaxiBots and Beyond
One trend we have been watching for a while are autonomous vehicles, which made a ton of sense in this application. They are programmed to operate in a tight set of specific parameters which they cannot deviate from. These have been used extensively in manufacturing and warehousing, but they will find their way onto the flightline soon. Here’s one such example:
The Lahav Division of Israel Aerospace Industries has developed a semi-robotic towbarless tug called a “TaxiBot.” The TaxiBot transports the plane from the gate to the runway and back, eliminating the need to burn fuel taxiing to and from the runway. The TaxiBot has a driver who ensures the plane’s nose wheel is lifted correctly, but after that, pilots in the aircraft control it from the cockpit.
Final Thoughts on Towbareless Tugs
Towbarless aircraft tugs offer a lot of benefits including increased operator visibility, easy maneuverability, and optimized control and braking. From a former tug operator, this is extremely motivating. There is nothing worse than that feeling of the tug chugging along a little bit after you hit the brakes, or sliding in the rain when you have it hooked up to a fully-loaded jet.
Electric towbarless tugs are a sustainable option, reducing emissions and operating costs. They might have higher upfront costs, but they are a winner in the long term.
Finally, when you choose an aircraft tug, consider factors such as towing capacity, maneuverability, and safety features. Modern tugs are much safer, and employ tech to stay cutting edge and safe, so look around.
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