A Short History Of Aircraft Ground Support Equipment And Ground Power Supply Units Explained

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Air travel has changed a lot since its humble beginnings. It all started with the Wright Brother’s first flight about 100 years ago and since then, the aircraft has become an integral part of modern life. The industry changed a lot since then.

For instance, in 1958, more people crossed the Atlantic by ship than by plane. Now, crossing the Atlantic by ship is simply inconceivable. Also, 50 years ago, the largest transportation companies in the United States were all railroads. The distance between distant major cities, like New York to Los Angeles was measured in days, now it’s hours. Hawaii, for instance, attracted just 150,000 visitors in the 1950s. Airports were few in the country, and ground support equipment, like a simple dolly or an aircraft ground power supply, were almost unheard of.

Now, airports have a plethora of ground support equipment that makes operations easier, more efficient and safer for passengers. There are multiple ground support providers who offer excellent service and tools, like Hobart ground support. The industry evolved massively, but how? Let’s see how has the air travel industry became so powerful.


Wilbur Wright and his brother make the first sustained flight on a freezing December day in 1903. They took off from a sandy hill at Kill Devil Hills, aboard their Wright Flyer into a headwind of more than 27 miles per hour. They only flew for 35 yards, but it was a success.


The first airplanes start to see limited military service as reconnaissance aircraft. Some of them are used as early bombers, but their use is very limited. The bombing runs steadily grow in number and the first auxiliary power unit becomes active. It is used to provide the initial start-up for the piston engines. The machine helps ground workers and makes the whole process far easier.


The first generators are becoming active at airports, making them out of metal office furniture and damaged air compressors.


This is the year we see the first tugs. The initial tugs were simple vehicles similar to forklifts and are used to move airplanes while on the ground.

The 1940s

The war has expanded the ground support industry and the aviation industry enormously. Major manufacturers come with multiple devices and equipment. For instance, the US army is supported by more than 45,000 new ground support generators and 100,000 welders designed for the aviation industry. Ford supplies tugs, with more than 10,000 of the still active after the war. Tens of thousands of tractors are also active at airports, both civil and military, during the war.

The 1960s

Major American manufacturers enter the ground support equipment industry, including GM, who launches self-propelled GPUs capable of producing a 400Hz alternating current. These state of the art GPUs are designed for major airlines and operators. The new aircraft ground power supply unit can be used for virtually any aircraft model at the time, making ground operations much more easy and safe.

The 1970s

The first electric tugs appear in American airports. They are designed as a more practical alternative to the diesel ones. They are more reliable, easier to handle and much more adaptable to airport environments.

The 1990s and 2000s

Ground support equipment evolves tremendously and now is a critical component at every airport. Virtually all ground operations are completed with ground support equipment. Dollies, tugs, tractors, ground power units, air starter units and a plethora of other pieces of equipment are active at all major airports worldwide. Ground operations are more effective and safer than ever.

Aircraft Ground Power Supply Explained

These devices are known in the industry as GPUs and are important ground support equipment. Initially, they were developed during World War I to start the engines. Over time, they evolved tremendously but they still have the same important role in the aircraft industry.

They are used to provide electricity to airplanes when they are on the ground. Obviously, during flight, the airplane can produce its own power, but when it’s parked, it requires an external supply of electricity. Usually, the connected power is around 115V at a frequency of 400Hz.

Most types of aircraft require just an external ground power supply, but larger models may need more than one. For instance, the massive Airbus A380 needs 4 ground power supply units, with a total power of 4 x 90 kVA.

There are two types of Hobart ground support units:

Fixed Units

Fixed units are reliable and more powerful than mobile ones, but are more expensive. Generally, they provide a 400Hz power, but they come with an adapter that can convert the frequency, as required for each type of aircraft. Centralized systems may employ multiple fixed units and can distribute the power to multiple aircraft at the same time. Power is either coming from the grid supply or can be generated by diesel or gas generators.

Mobile Units

Mobile ground power units are used when fixed solutions are not reliable or do not exist. In some situations, mobile solutions can be a better alternative because they are adaptable to multiple types of aircraft. The mobile units are either self-propelled or must be lifted, towed or pushed. The power is generated by diesel, gas or solid fuel generators.

The Frequency Of Ground Power Units For Airplanes

The frequency of virtually all ground power units is 400Hz. This frequency was chosen because it allows a more compact design, lightweight construction and a better technical solution for the electric components. The generators which create the 400Hz power will use less copper in their magnetic cores and wiring when compared to similar 50 or 60Hz generators. This is very important, as the whole Hobart ground support unit becomes lighter and more easy to handle or use. Because the internal wiring of airplanes is fairly short, the negative aspects of larger voltage at 400Hz are not very serious. After all, weight is more important in the aircraft industry.

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