In The 1980s, Hungary Tried To Reinvent Airports With A Giant 74,000-Pound Bus That Was Also A Jet Bridge And A Baggage Tug

The process of boarding a commercial plane today usually isn’t very exciting. Depending on where you’re flying out of, you might board your plane through a jet bridge, a walkway that leads to a mobile stair, or maybe a bus that leads to a mobile stair. In decades past, several innovators tried to reinvent the airport experience. Perhaps the most ambitious of which was the Ikarus 692 PALT. This marvel of a bus was meant to drive passengers straight from their hotels to a waiting plane. How? The PALT had a built-in jet bridge that connected to a commercial plane on the other side.

Frank Der Yuen’s invention of the jet bridge in 1959 changed how much of the world boarded aircraft. In the decades before the jet bridge, passengers often had to walk out onto the ramp where the plane was parked and then climb a set of mobile stairs into the waiting aircraft. Some planes were designed with airstairs built in so that less infrastructure was needed for loading.

These systems worked, but they had their limitations. If the weather was less than perfect, passengers were cold or wet as they boarded the aircraft. If any passenger had difficulties climbing stairs, that slowed down boarding as they needed help getting into the plane. Airlines figured that if there was a way to protect passengers from the weather and ramp environment, boarding would be quicker, safer, and more comfortable.

It’s hard to pin down which airline or inventor first came up with the idea of the jet bridge. As USA Today notes, United Airlines invented something called the Air Dock in 1954. This was a covered bridge that permitted passengers to walk from the gate to the aircraft without dealing with being on the ramp. In 1959, the airline reached out to the Pacific Iron and Steel Corporation of Los Angeles for a connector between an airport gate and an aircraft that worked like the gangway to a cruise ship. That year, America’s largest airport hubs would get jet bridges serving United Airlines, American Airlines, and Delta Air Lines aircraft. Many of these bridges adopted the design pioneered by Der Yuen.

The jet bridge wasn’t the only solution to the question of how to board planes in the Jet Age. In 1962, Washington Dulles International Airport adopted Eero Saarinen’s mobile lounge concept. The mobile lounge was basically a large bus that contained a lounge inside. Passengers would walk into the lounge, and then the lounge would drive to a waiting aircraft, lifting itself up to permit boarding.

In 1979, Sovam introduced its own concept of a mobile jet bridge with the Aerobus AL150, which was used at Charles de Gaulle Airport in France.

The idea the folks of Ikarus had was far grander than any of these ideas. What if the bus that you caught at your hotel or in the city bypassed the airport entirely and drove you straight to the plane? That was the concept behind the Ikarus “PALT” Airport Handling System, or Passenger And Luggage Together.

Once One Of The World’s Largest Bus Manufacturers

The Ikarus Body and Vehicle Factory is not a well-known producer of buses here in America, but in decades past, it was once one of the largest producers of buses in the world. The Hungarian National Digital Archive tells the manufacturer’s story:

The story of Ikarus goes back to the story of the contracted parent companies, until 1895, when Imre Uhry – son of a wheel- and coach-maker – established his firm under the name Blacksmith Workshop and Coach Factory near Városliget in Budapest. Uhry ploughed back a part of the income into the enterprise and spent it on developing investments, thus basing the future successes of the company. By the mid-twenties, one could found graceful chariot-like buses – fabricated in Uhry’s factory individually with wooden frames – in many Hungarian cities. Although the boom of the firm was broken by the Great Depression at the end of the nineteen-twenties, the company was revived by Uhry’s children owing to the family cooperation and the financial support of relatives; and production could go on.

As of the mid-thirties, the firm gradually employed developments that laid the foundation of switching from retail manufacturing to large-scale machine production. Besides changing wooden-framed to metal-framed vehicles, they also modelled the types produced in large quantities with scale mock-ups as of 1936. During the forties, engineering investments and other developments due to increased vehicle demand in the WWII resulted in company growth. During the war, the predecessor of Ikarus became a large company with an employee headcount of almost one thousand. After the war, the company was nationalized and merged with two other companies.

1947 meant an important milestone in the life of the company: the first Tr-5 model was finished. It was fabricated onto MÁVAG undercarriage, had a mixed metal and wooden car-body, and it had other features like headwall radiator, recessed destination board and pneumatic remotely controlled folding door that was a characteristic part of the city bus transport style until the end of the 1980s.

What helped thrust Ikarus into a global bus powerhouse was its adoption of a conveyor belt-based production line. Each bus would scoot down the line, arriving at workstations prepared with the workers and tools to complete the next step of the build. Constructing the buses on a line, like the way cars were built, meant that Ikarus was able to mass-produce hundreds of buses and ship them across the Soviet Union. The most famous Ikarus was the 200 series, of which more than 200,000 copies were made between 1968 and 2002.

As Buses Magazine reported, at the peak of Ikarus production in the 1970s and the 1980s, the company pumped out 13,000 buses a year. About 80 percent of those went to members of the USSR. Ikarus sold buses in 84 countries, including the United States and Canada. Americans might know Ikarus best for the Crown Coach Corporation’s Crown-Ikarus 286, which is an Ikarus 280 articulated bus adapted for the U.S. market. Over in Canada, this bus was built by Orion Bus Industries and sold as the Orion III.

Yet, for all of its triumphs, not everything Ikarus made was a hit. The buses it invented to revolutionize airports weren’t just a flop, but they apparently never delivered a single real passenger to a plane in a live airport environment.

Combining Different Airport Equipment Into One

According to the Polaris Ikarus bus history blog, the seeds of the Ikarus PALT project were planted in the 1970s. In January 1974, Antal Gulyás, a designer at Ikarus, wrote a proposal for a futuristic bus. The Ikarus 266 Airoporter had two innovative ideas for its day. Since the bus was intended to drive on the smooth tarmac of airport ramps, it would have a super low floor and ground clearance since the bus wouldn’t be expected to traverse any obstacles. At the front of the bus was an accordion-style bridge that extended out using a hydraulic ram.

The idea of the Airoporter was that one bus could replace two airport vehicles. Instead of having one bus and a stair truck, the bus and the stairs could be combined into one. Ultimately, the Airoporter never went further than an idea, but it was clear that people at Ikarus were thinking about this concept.

The impetus for the PALT system would come from an invention, No. 14605, by engineers Valér Szendrődi, Tibor Vass, Tivadar Varga, Gyula Radics, and Károly Gyurics. This patent, which was filed in 1978, was entitled “Development of a universal, self-stepping bus family suitable for synchronous airport passenger and baggage transport.” Later, as the idea evolved beyond a bus and into an entire airport logistics system, the description changed to “Airport complex person and material handling method and system.”

The Ikarus invention was even more ambitious than the Airoporter. Ikarus determined there was a lot of inefficiency in airport operations because so many vehicles were involved in preparing a plane for departure and arrival. Shuttle buses carted passengers out to the plane, a stair truck or bridge provided access to the jet, and baggage tugs had to haul luggage out from the airport.

Ikarus also saw the whole flying experience as inefficient. Travelers would have to ride a bus from their hotel or the city with their luggage in tow, check their bags, walk to their boarding area, ride a bus, and then climb stairs. What if the bus could replace many of those steps? What if the bus could even bypass the terminal entirely and drive you straight to the waiting plane from your hotel?

To facilitate this, Ikarus designed a double-decker bus where the lower deck was purely for passenger luggage, while the upper deck was for the passengers. The lower cargo compartment was not like the basements that you’d find in a typical bus. In this application, the cargo compartment runs from end-to-end, and Ikarus concocted a special conveyor belt and tray system.

How it worked was that, at your origination point, be it an airport, bus station, or hotel, you’d get your ticket, go through customs, and then dump your bag in the tray. Once the tray was full, the conveyor belt ran the tray straight into the conveyor on the bus. That way, there was no luggage collection or sorting needed.

Once all passengers and bags were loaded onto the bus, the bus would drive straight to the plane. At the plane, the bus would use a hydraulic system to lift its built-in jet bridge into place. Then, as passengers walked from the bus interior to the plane interior, a tug would come by towing a special cart meant to retrieve the trays from inside the bus. The tug then brought the carts over to a special cargo loader, which elevated the luggage to the plane.

The First PALT Bus

Ikarus presented the concept to the public at airport trade shows in 1980 and 1981. Apparently, the reaction was great enough to justify continuing development. The strategy called for one prototype bus to be built in 1982, a second prototype to be built in 1983, and bus production to begin in 1984. Ikarus produced the first prototype of what it called the Utast és Poggyászt Együtt Mozgató, or UPEM, in 1982. That translates to English as Passengers and Luggage Moving Together. As international interest in the system grew, Ikarus changed the system’s name to English, becoming PALT, or Passengers And Luggage Together.

The first PALT bus was called the Ikarus 692.01, and it was a massive, innovative vehicle. The Ikarus 692.01 was designed to replace the shuttle bus, the baggage truck, and the mobile stair. Designed by Ferenc Örsi and developed with help from the Budapest University of Technology and Economics, the bus stood 13 feet high, was 9.18 feet wide, and stretched 46 feet long. Piled on top of the coach’s four axles was a bay large enough to accommodate the luggage of the 150 passengers riding on the upper level.

The bus was designed so that departing passengers would walk through the large doors on the back of the bus, while the conveyor belt system rolled their luggage into the compartment. Once loaded, the bus would drive from the terminal to the apron, where it would drive up to the plane.

At the plane, the hydraulically powered jet bridge would extend to reach the aircraft. Stabilizer jacks would also extend under the bus to create a secure platform. The designers noted that previous attempts to make a jet bridge bus were clunky because the height of each stair within the extendable bridge varied between aircraft. That was believed to be a tripping hazard. To fix it, the Ikarus 692.01’s jet bridge extended out only one small section at a time. The bridge onboard the 692.01 had nine extendable sections. Just enough sections would be raised to reach the aircraft, while the other sections would remain stored. This meant that the stair height was the same, no matter whether the target aircraft was a narrowbody or a widebody.

One of the quirks of the 692.01 PALT was that it wasn’t a road vehicle. It weighed a staggering 74,300 pounds and was too large to navigate city streets. Also, it wasn’t exactly fast. Power came from a RÁBA-MAN D2356 HM6U 10.6-liter inline-six diesel with 220 HP on tap. Top speed was a leisurely 37 mph. There were also two driver positions, as the driver can operate the bus on the lower level below the stairs or on the upper level on the other end of the bus.

Building this bus captured the attention of much of Hungary. Soon, the Hungarian government found itself interested in the PALT concept. Then, a consortium was formed between Ikarus, AUTÓKUT, Csepel Car Factory, Transinvest Transportation, UVATERV,  and the Licencia Inventions Sales Company to make the airport handling system a reality.

Ikarus and AUTÓKUT designed the buses, UVATERV designed PALT buildings and the baggage system, and Transinvest developed export plans for the production PALT system.

More Than Buses

Ikarus and the partner companies brewed up an ambitious plan. There were to be four different kinds of PALT buses. The first type of bus would be an articulated bus that carried passengers and luggage from hotels and from the city to a waiting plane. The second bus was a single-unit transit bus that did not have a luggage compartment, but still drove passengers from the city to a waiting plane. These two buses were expected to drive at up to highway speeds.

The third type of bus lived only at the airport, and drove passengers and their luggage from the terminal to a waiting aircraft. The Ikarus 692.01 was this type of bus. The fourth type of bus was an airport shuttle bus without luggage space, but with a built-in extending jet bridge.

Ikarus saw these four types of buses running four different types of services. The PALT City Service involved setting up ticketing and customs within hotels and bus stops in the city. The bus would drive passengers straight to a waiting plane. The PALT VIP/Crew Service functioned similarly to the City Service model, only the buses were supposed to be more luxurious and served special passengers like celebrities and politicians.

From here, there was the PALT Apron Service, which was supposed to shuttle passengers and luggage from the terminal to a waiting plane. Finally, there was the PALT Transit Service, which utilized a PALT bus to shuttle people around the airport from terminal to terminal or aircraft to aircraft.

Ikarus also proposed different airport concepts, where PALT buses could bypass the airport terminal entirely to reach planes or filter passengers through the airport, onto other PALT buses, and then to the aircraft.

That was the whole twist to the PALT system. The consortium of companies developed an entire ecosystem. In addition to the PALT buses, there were PALT terminals, PALT baggage carts, PALT trays, PALT lift trucks, and PALT ports. While PALT terminal buildings were optional, you needed the rest of the PALT gear in order for the PALT buses to work. All of this adds all sorts of complexity, as you aren’t just replacing vehicles anymore, but existing systems.

The Prototypes

Yet, this was thought to be the future, and these companies pushed on. Subsequent prototype buses were built, including the Ikarus 695.01 and the 695.02. These two articulated buses experimented with where passengers would board the bus. Planned PALT buses included the 692.03 transit bus (no luggage compartment), the 696.01 transit bus with a luggage compartment, and the 697.01 VIP bus. All of the road-going buses would be able to drive faster than 62 mph to be able to run on the highway.

The 1983 Ikarus 695.01 was a beast in its own right. It was a 59-foot-long articulated double-decker bus that carried 110 passengers. The 695.01 was designed with both road travel and international markets in mind. This meant that it weighed a more reasonable 46,300 pounds and stood only 12.8 feet tall. The engine compartment was also designed to accommodate foreign engines for customers in different countries. Power in the 695.01 came from a Steyr Motors 9FU-A turbodiesel with 240 HP on tap. Like many old-school articulated buses, the rear articulating section was a trailer, and the engine powered the center axle. That power reached the axle through a Voith 851 automatic transmission.

The 695.01 was designed to pair seamlessly with an Airbus A300, as that was the plane that was exceedingly popular in Europe at the time. Ikarus even developed a system that would give the bus driver a measured distance between the bus and the aircraft door to reduce the chances of an accident.

The 1984 Ikarus 695.02 was shorter and featured a RÁBA-MAN D2356 HM6U diesel, but a Soviet Lvov GMP 3-80 automatic transmission. Apparently, this bus was built purely to test the transmission and to gauge Soviet interest in the bus. Ultimately, the Soviet Union wasn’t interested in the 695.02.

The last prototype built for the PALT program was the 1985 692.03 PALT. This was the physical manifestation of the planned PALT inter-terminal bus that didn’t have a luggage compartment. This 55-foot bus was 9.8 feet wide and had a floor that was only 19 inches off the ground. It carried up to 160 people.

A unique feature of this bus was its double-ended nature. There was a driving cab at both ends of the bus, and all four axles steered. Because all tires were steer tires, the bus could turn within its own length. The drivetrain, which was mounted near the front axles, featured a reverser gear after the transmission, which allowed it to drive at top speed in any direction. That said, only one side of the bus had the PALT extendable jet bridge.

Sadly, due to image rights restrictions, I cannot show you the interiors of these buses. But the Polaris Blog has a lot of fantastic PALT interior and structure images of the buses.

The great part about the 692.01, the 692.03, the 695.01, and the 695.02 buses was that they were all functional from their drivetrains to the extendable jet bridges. Ikarus drove them around to trade shows and demonstrated how they could change aircraft boarding. They weren’t just concept vehicles.

The PALT Program Falls Apart

Ikarus and the consortium planned to build even crazier buses, including the 692.05, which would have been so long that it could have ferried 200 passengers to a waiting plane. Ultimately, the 692.05, the 697.01, the 696.01, and other planned variants were never built.

As the Hungarian transportation publication IHO writes, the push to get the PALT system into production was grand, with the Hungarian government and local newspapers touting the PALT system as a great innovation poised to change aviation. Hungarian officials even attended trade fairs as special guests of Ikarus.

Unfortunately, each of those trade shows ended with the same result. Airports weren’t interested.

The problem was that the PALT system went too far. Ikarus wasn’t interested in selling an airport on just the bus. It sold the PALT as a package deal. You had to get the buses, the luggage trays, the baggage carts, the lift trucks, and all of the other infrastructure to make the buses work. This would have been expensive and would have required an extensive overhaul of the world’s airports.

The other problem was that, in trying to streamline airport operations, Ikarus and the consortium actually made it more complicated. The buses were supposed to combine the shuttle, baggage truck, and stair truck into a single vehicle. However, the PALT design still required a tug to retrieve the luggage from the bus, anyway, defeating the purpose.

Further, the buses would have changed how baggage handling works. In a typical airport, your luggage goes through a handling and sorting system, then starts getting loaded onto the aircraft before boarding begins. In a PALT system, the baggage doesn’t even begin to leave the bus until boarding begins. Then there’s the problem with having giant double-decker buses running around an airport environment to every single plane.

Perhaps the final nail in the coffin was infrastructure. The PALT system was designed to work best with custom-built terminals and bus stations. Airports weren’t interested in adding more buildings just for PALT. Why do all of this work when most of the world has already figured out that the jet bridge works just fine? Even the airports that didn’t have jet bridges for every gate weren’t interested. They already had apron buses, and they already had stair trucks. Why ditch these vehicles when they worked fine?

An Obscure Part Of History

So, in 1986, the PALT program was halted, and then eventually cancelled. The prototype buses were abandoned and forgotten. To illustrate just how much everyone stopped caring about PALT, the image below shows what the Ikarus 695.02 looks like today. It currently lives in the Aeropark museum in Budapest, and there is interest in restoring it to its former glory.

The PALT system was one of those ideas that looked really good on paper. Why have three vehicles when you can condense them into one vehicle? Why have passengers actually visit the terminal when you can turn a hotel into a mini terminal? Why have passengers walk when they can be driven to a plane?

It’s sort of wild that the PALT project even got as far as it did. All of these companies burned tons of cash building prototype buses despite not having any interested parties. It seemed like the companies were thinking that the buses would probably induce demand. Yet, in a way, it’s still really cool that PALT got to the prototyping stage, because it produced some of the weirdest buses in history.

Top graphic images: Ikarus Archive