Benjamin J

What is this piece of ground equipment?

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For the purpose of some airport scenery I'm working on, I'm trying to figure out what ground equipment they have littered around the tarmac. For the most part I've been pretty successful, but I can't for the life of me find out what the thing pictured below is. Usually these pieces of equipment seem attached to the terminal with a big yellow hose, making me think it's some kind of air unit. Any idea what type of machinery this is, and if so, what make and model it might be? I was thinking we have a good collection of aviation people here, so perhaps somebody has an idea. I might help to know this is an airport in the US, too... (though I don't wanna say what airport I'm working. Not yet, at least) I need some reference pictures and if possible some kind of schematic to model it properly. Any help is appreciated!


EDIT: Thanks to help so far I've been able to figure out that this is a portable PCA unit by Twist Aero, model number PCA030480WH, with a separate 'hose management' unit on top called "BoomAir". I contacted Twist Aero for confirmation and am hoping they will be nice enough to respond to my weird request. In the mean time, if anybody can give me an idea of how tall/wide such units typically are, that's be highly appreciated. So far I haven't been able to find any sort of drawing or schematic, or even a proper set of images.




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Portable air conditioning unit?  Possibly a portable ground energy unit.  I have seen similar units attached to the underside of jetways.  No jetway, then use the portable model??

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Chipper/shredders for the luggage ???  Actually, I'm pretty sure they are Preconditioned Air Units (PCAs).  There's probably dozens of different manufacturers; but you may want to try looking up Jetaire (JBT), Adelte, or TLD for a match. 

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23 minutes ago, MadDog said:

Chipper/shredders for the luggage ???  Actually, I'm pretty sure they are Preconditioned Air Units (PCAs).  There's probably dozens of different manufacturers; but you may want to try looking up Jetaire (JBT), Adelte, or TLD for a match. 

Oh my, your mention of PCA seems to have saved me! Thank you!

I was endlessly staring for a brand name and spotted "Aero" on the side of that thing. I previously tried searching for it but came up with nothing, but "Aero PCA" gave me some images of PCAs by a brand called "TwistAero"! So that must be the right brand. Some of their units appear to have that 'thin' box on top, so I'm one step closer. Thanks for the help so far, getting closer!

EDIT: turns out that the 'thin box' on top is for 'hose management'. Basically it rolls up the hose for you, like a vacuum cleaner does. One mystery solves...


EDIT2: Found it! The model number appears to be PCA030480WH, but there's no images at all for it. Eventually what I need are some specs... So if anybody has any idea how tall/wide etc these things typically are, that would be quite helpful

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I see the name Aero on the side. Can barely make it out.  Looked through their list of products on their web site and these are the closest I could find. The component on top may be some type of adapter for use in specific situations. Larger photos might help.

Edited by fppilot

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18 hours ago, Benjamin J said:

For the purpose of some airport scenery I'm working on, I'm trying to figure out what ground equipment they have littered around the tarmac.

Despite the fact that it looks like equipment is littered about, it really isn't. Everyone has to know where equipment is and there are only certain places you can leave equipment and some places you can only leave it if it is attended. Ramp equipment-wise, you have:

EBT (Electric Baggage Tractor): These are the workhorses of the airport, they tow equipment such as Baggage Trailers, Aircraft Steps, GPUs etc about. They are as the name suggests, electric, this is so that they tow baggage trailers into the baggage halls to allow the suitcases to be placed on the carousel for passengers to retrieve, since you could not drive a diesel or petrol vehicle into the building. Since they are electric, they have to be charged up every once in a while, so most service agent companies has a location on the airport somewhere that has a few charging points for these. Typically this would be underneath a pier, or in between some stands, but if you see a lot of these parked up very close to one another, the likelihood is that is where the charging bay is. The one on these pictures is probably the most common types you'll see, made by Charlatte:

DBT (Diesel Baggage Tractor): Pretty much the same thing as an EBT, although for obvious reasons, it cannot tow vehicles into enclosed buildings like its electric counterpart can. On the plus side, these can typically handle a lot more weight than an EBT, so they would be the preferred choice if you wanted to tow really heavy equipment. They are most often made by a German company called, Mulag. But not always, here's a picture of a DBT:

Curtain Trailer/Baggage Trailer: Everyone knows these things, they are what the suitcases are loaded onto to be carried out to the aeroplane, or loaded onto when removed from the aeroplane. They can typically hold about 40 average sized suitcases. So, you will typically see around five of these things go to something like an A321 when it is being either loaded or offloaded, and this is because it will be carrying about 180-200 bags in its forward/rear holds, which is about the amount of bags you can fit on five of these curtain trailers. However, at many airports, even though either an EBT or a DBT could easily pull five of these, it probably won't be allowed to do so. You used to be allowed to, but in these PC/Health and Safety-obsessed days you can't (too much danger of them concertinaring in slippy conditions), so the maximum you can pull when they are empty is four, and the maximum you can pull when they are loaded, is three. Thus you will see two EBTs take five trailers out to an A321 at most airports. Here's a picture of one:

Cage trailer: Similar to a curtain trailer in size and appearance, but it has caged lockable wire mesh sides instead of canvas flaps. This so it can be used to transport hazardous goods such as radioactive materials, etc.

Elevator/Conveyor/Belt Loader: This is the small conveyor vehicle you see going up to the aircraft so that bags can be loaded/offloaded. Like most airport mobile service equipment, they are typically diesel although in future they are likely to be electric. The belt platform can be raised and lowered. On something like a 737, it doesn't need to be raised much to reach the holds, but on something like an Airbus A330 it can be raised to a very steep angle so you can access the rear-most bulk cargo hold for things like the odd loose bag. Crew bags are put in this rear bulk hold too, all the other stuff such as cargo and passenger bags on large aircraft such as the A330 are typically put into cargo 'cans' and loaded via a high/low platform. Here's a picture of a typical belt loader:

Cargo Loader/High-Low/Scissor Lift: This is for uploading and offloading ULDs, or 'Cans' as they are typically called. Cargo and baggage is often loaded up into cans prior to being taken out to the aircraft. This makes the loading process quicker when at the aircraft, however, it can usually only be done for long haul flights where check in times are invariably longer, because after the passengers have checked their bags in, they are then screened, sorted and go to the 'bag hall' to be loaded onto either curtain trailers or cans. Needless to say, loading up 350 bags into a few 'cans' takes a bit longer than slinging 150 bags onto a few curtain trailers, so typically, you'll only see cargo cans used on bigger aeroplanes like 747s and A330s, not on smaller stuff like 737s and A320s, where loading bags individually is far more common and just more practical in real terms because of the fast turnarounds and short check in times. 'Cans', more properly called Unit Load Devices (ULDs), come in various sizes to fit various aeroplanes, although often aeroplanes are designed from the outset to utilise a common size of ULD, for example, the A330 is a widebody airliner, so it uses an 'AKE/LD3'-sized ULD, which is a ULD size that also fits other widebodied aeroplanes including the L-1011, MD-11, DC-10, and various Boeing widebodied airliners too. These vehicles have a powered roller floor system which can load the ULDs on and off it and can also rotate them when they are on its loading platform. Here is a picture of a High/Low/Cargo Loader:

Here is a wiki page about the cans themselves:

Unit Load Device Container Dolly Trailer/LD: Obviously, you need a suitable trailer to tow ULDs about on, and they come in various sizes. They have a roller ball load area which is similar to what you find in the cargo hold of an aeroplane which uses those ULDs, this is to assist in loading cans onto them. At the sides, there is a lug locking system which can be lowered to allow cans to be rolled onto them and then flipped up to lock them in place for transport, the cargo hold of an aeroplane has a similar system so the cans don't move about in flight. Here is a picture of a small ULD trailer:

Potable Water truck: as the name suggests, this is a small tanker vehicle which can load drinkable water onto an aeroplane. Since water is pretty heavy, the tank is often quite small, so it can be carried on a small truck so there is room to maneuver it up to an aeroplane. Here's a picture of one:

Sewage Collection Truck/Septic Tank Vehicle/Honey Wagon: This is the vehicle which collects the stuff from the toilets of the aeroplane Like the potable water truck, since it carries a lot of weight, its tank is quite small so it can easily move around the aeroplane. Here's a pic of one: 

TWA Boeing 747 - Vintage Airliners (@VintageAirliner) | Twitter

Fuel Pumping Truck: at most airports, they don't use fuel tankers, instead the fuel is piped underground to each stand and a pumping truck connects a pipe to an outlet on the stand located near where the wing of the aeroplane will be, and then connects a pipe to the aeroplane and then pumps fuel into the aeroplane from an underground tank. What you will see when this takes place, is that the pump truck also connects an earthing wire to a metal part of the aeroplane (usually a landing gear leg) to prevent static discharges. This is called the 'bonding strap' and is painted a dayglow green colour. Fuel pump trucks are the only vehicles which are allowed to drive under the wing of the aeroplane and all other vehicles are supposed to keep at least 6 metres clear of it and not to block it in in case it has to evacuate in the event of a fire. At the head of the stand (i.e. the front bit of the stand where the terminal building is), there is usually a panel with a few things on it, these include an emergency telephone, a keypad where you can program in the size of aeroplane expected on the stand so the doppler safedock system can recognise the aeroplane and give it steering and distance guidance for when it taxies onto the stand, and most importantly, an emergency fuel shut-off button, which you can press to shut down the underground fuel system which the fuel pumping truck is using if something goes wrong. Sometimes when the fuel system goes unserviceable, an actual tanker will be used to load fuel, but this is very rare although it did happen at EGCC earlier this year when a lightning storm damaged the underground fuel pumping system. You might be wondering how the fuel truck guy knows how much fuel is on the aeroplane and how much he's put into it. Under the wing, there is a fuselage lift up panel, and under that there is a board with digital readouts and a few flip switches on it. It displays information about what fuel is in what tank, so you will occasionally see the fueler going over to this and checking it. Here's a picture of a fuel pumping truck connected to the underground fuel system and the aircraft:

Passenger Elevator Courtesy truck/Catering truck: These two look very similar. Typically they will be a truck with a body capable of being raised on scissor jacks. The passenger elevator is for loading and offloading wheelchair bound/limited mobility passengers and can usually be recognised by the fact that it looks quite nice and has windows. If it is the catering truck, it most likely won't have windows and will probably say sky chefs/gate gourmet or some such on it. This is the one loading the meals and offloading the used/empty food trolleys. Here's a pic of one of these vehicles: 


Steps: Unless using an airbridge/jetway/jet bridge on your aeroplane, you'll need some steps to get on and off the thing, although even when airbridges are used, typically the cleaners who service the aeroplane will use portable steps on the rear of the aeroplane and passengers will disembark at the front via the jet bridge. The other time you might put steps on an aeroplane is if an engineer wants to board the thing and its on a remote stand without a jetway, or when towing the thing, since you have to put someone on to work the brakes, and get them off after the tow. The tug should typically have a headset connection to the person in the cockpit in case something goes wrong, but this is not always done, and here's some trivia for you: If you are towing and you hear on the headset 'X-Ray, X-Ray, X-Ray', this means either the brakes on the aeroplane have failed or the towbar has disconnected or sheared off, and this is your signal to get the f*** out of the way in the tug so you don't get run over by a 400,000lb airliner lol.

Stairs come in all kinds of shapes and sizes, from ones you can hand push, to motorised hand-steered ones, ones mounted on trucks and ones you can tow, although there are typically two sizes. Ones for big widebody aeroplanes and ones for regional/samller aeroplanes. The height of both can usually be adjusted somewhat too. No need for a pic of these, you know what these look like!

Pushback Tractor/Tug: These are for either towing an aeroplane or pushing it back off the stand. They come in all shapes and sizes and two types (soon to be three). They either connect to the aeroplane with a towbar, or the vehicle cradles the nose wheel and lifts it up. The third type you might soon start seeing more of, is a remotely operated on which the crew of the aeroplane can steer, these are new and very rare, but they are trialing some of these at London's Heathrow apparently. Never seen one of those myself.

This is the other thing you'll see lying around at the head of stands quite often - towbars. There are different types for different aeroplanes, i.e. the same type of bar can be used on an A318/A319/A320/A321, but the 737-600/700/800/900 use a different common type, and needless to say, bigger aeroplanes such as a DC-10 or A330 would use much heavier ones than those used on a 737, so you typically find about ten different types of towbars kicking around although they are stored in specific places, for example, we keep ours at the side of Stand 28 at EGCC and Jet 2 keep their at the side of Stand 27. Here a pic of a typical pushback tractor, this is one of the towbarless ones which lifts the nosewheel:  


Ground Power Unit (GPU): If you look at the picture above, you'll see a GPU. You'll also see that it isn't chocked, which is should be lol. These are used on stands where the built in power of the stand is unserviceable, or on remote stands where there is no built in power. They have a diesel engine and they are basically just a mobile generator which can supply different voltages (typically 28 volts). You can see two cables coming off it. These are normally stored in the long tray area you can see them coming out of. The reason there are two, is because larger aeroplanes require that, smaller aeroplanes only use one, so, you'll see two going to an A330 or some such, and only one going to a 737.

Air Starter: To crank an aeroplane's jet engine, you need two things: A supply of air and some electrical power. Now it is true that you can start a jet aeroplane without any of these providing it has a decent battery and an APU, but it isn't always the case that aeroplanes have these available. If they are available, you can start the APU off the battery power, and then bleed some air off from the APU in order to crank the main engines. If you can't do that, a GPU can provide electrical power and a air starter can provide the necessary bleed air. This is one of the few situations where an airliner will actually start an engine whilst on the stand instead of cranking it whilst pushing back and you have to be careful to ensure all the equipment and personnel is clear of the engines when doing that, for obvious reasons. Here's a link to a company which makes Air Starters and also makes air conditioning units like the one on the OP which you were asking about, so you should be able to determine its size from this link, but if not, note on your pic that the small red 'cones' will give you some idea of its size as they are typically the same height as regular road cones:

De-icer/anti-icer truck: This does what its name implies. It will pretty much always start on the port wing of an aeroplane and work its way around it. Here's a pic of one:

Passenger buses/Crew Buses/Cleaner Vehicles: Passenger buses are typically quite low in height. This is not so that they can drive under the wings, it is a precaution in case they drive under the wings. Crew buses are usually just your typical 12 seater minibus and the same goes for cleaner transport vehicles although as is the case with all vehicles on an airport, they all have to have amber flashing lights, all have to display an airside vehicle permit (usually a circular badge in the window) and all drivers have to have an airside driving permit, for which there is a medical.

Note that in pretty much every case. All of these vehicles will be on the starboard side of the aircraft. The exceptions are the stairs, passenger buses, engineer's vehicles and the de-icer truck, which you will often see on the port side so they are out of the way of the ramp people.

Fixed Electrical Power (FEP): At the head of most stands, you will see a small trolley on castored wheels which is attached to a pantograph. The pantograph allows it to be extended out to aircraft of different sizes. This trolley is the FEP, which does the same thing as a GPU. It is almost always painted a very bright yellow and when its pantograph is collapsed in so it is out of the way, it sits in a small area near the jet way. This area is usually protected by crash barriers to prevent vehicles backing into it etc. There are usually racks in that area too, these are where you can places things like cones and chocks.

Cones/Chocks: You'll see these all over the p[lace at an airport, people leave them lying about, but they should be at the head of the stand. Seems rather obvious why you'd put cones and chocks on/around an aeroplane, but there are specific reasons why cones and chocks are placed where they are on aircraft, and when this is not done. Typically, there will be five cones used. One placed 1m in front of each engine intake, to stop vehicles hitting them when they move around them. One on the tail, 1m out from it, to stop vehicles driving under the tail and potentially damaging the aeroplane. One on each wingtip, placed 1m out from it, again to stop vehicles driving under the wings. These also hopefully prevent passengers walking up to the engines too and arsing about with them, as some Chinese lady did recently when boarding, so she could throw an coin into the engine for 'luck'. Yes she really did do this!

Chocks are typically put on the front and rear of both main wheels and the front and rear of the nose wheel. Which means you need six, although some airlines are happy for you to only chock one main wheel and the nose, meaning you only need four.

The exception to this is when there is a weather warning, in this case, the nose wheel is not chocked so that the aeroplane can pivot a bit when the tailplane acts as a sail. This is so the landing gear and the tailplane doesn't receive any unnecessary shear force. No cones are put out when it is windy either, since they'd just blow away and create a FOD hazard. You will see green FOD bins on all aircraft stands and black bins (for engineer's waste) too.

Nitrogen cart: Aeroplane tires are inflated with nitrogen, so you will see nitrogen tank carts kicking about. Here's a pic of one:

Various service access platforms/other stuff: There are various ladders and access platforms kcking about, mostly painted yellow for visibility. You will also see large boxed trailers with things like kits for changing wheels in them etc.

Markings on the stand: There are a lot of markings on an airport stand, but as far as where you can leave equipment, the really important one is the Inter-stand Clearway. You can see this on the bottom right corner of this picture:


Notice that there is no equipment just lying about, it's all in this area if not actually being used. The inter-stand clearway is marked by a white line but there is also a red line adjacent to the white one; this indicates the wing projection area, i.e. it's where the wings might go when an aircraft is coming on or off the stand, so you leave equipment well clear of that line. The red cross hatched area (sometimes this is a white starburst pattern) is the area where the jetway might move to, so this is kept clear too. The aircraft is using ULDs and these are being serviced at the front and read holds, but there is also a belt loader servicing the rearmost bulk cargo hold where a few loose bags, crew bags, prams, wheelchairs and such will be placed (probably no more than 20 or so of these in total). The front wheel of this aeroplane is on its specific type marker to ensure the airbridge could connect easily. The red/white box near the front loader marks the fuel outlet where the fuel pump truck connects to. Some stands have an additional white boxed area marking which indicated where different wings might project to for various aircraft types. These are called the MARS Bars (yes really), it is short for Multiple Aircraft Ramp System. Note that this stand has some additional centre line markings for some unusual aircraft types. These are dashed, indicating that they do not use the automatic safedock system and would instead use a marshaller to direct these aircraft onto the stand.

Hope that all helps a bit.

Edited by Chock
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Hey CHOCK:  

Somebody has finally explained all the peripheral  ground services equipment in detail - thanks for that...

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Love informational threads like this.  The worst aircraft accident I was ever in was when ground equipment rammed my jet, I was the only pax left on board and thrown into a row of seats, bruising my hip and pride.  The aircraft I was told by the gate agent had to be ferried back to Denver, with the pilots on Oxygen, for fear of compromise in the fuse.  The accident never appeared in the NTSB search engine--happened in Jackson Hole in the late fall of 1999, which was my first business trip after my daughter was born.  I had to provide my services to three hotel clients up there, two at the ski resort and one in Jackson Hole proper, all owned by the same company that also owned a hotel in Capitol Reef Natl park in Utah. 

It was because of my work in Capitol Reef that they asked me to help them up in Jackson Hole some six months after I was in Capitol Reef.  My partner and colleague up there had worked with me on a previous project in Townsend TN, good young guy who had sadly hit a pedestrian and killed him earlier that year.  Not his fault but he was deeply hurt by the experience which is why they sent me on another trip with him, because I had prior counseling experience when I was learning to become an instructor.  We were all so sorry for what he must have gone thru as well as the pedestrian's family, which could not receive financial compensation due to the pedestrian being at fault jaywalking, which we all have done, poor guy. 


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wow, what a post, thanks Chock!

A bit off topic, but given that we have quite a few members who work in aviation jobs, it would be great to have regular AMA's (reddit term for Ask Me Anything), which is basically a Q&A session where a professional talks about his/her job, expertise or passion and answers questions from the community. It would be amazing to see AMAs from RW pilots, ground handlers, air traffic controllers or flight ops staff

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Wow, what a post Chock! Thanks for that info, should be handy when I try to figure out what any of the other equipment is :)

So I already figured out what this thing is yesterday (thanks to those posting afterwards though 😉. I appreciate you wanting to help out! See my edit in my opening post). As I mentioned I had reached out to the company (Twist Aero) that I suspected had manufactured the unit. They got back to me and very helpfully provided me with some pictures. It turns out this is a mobile 30 ton Boom Air/PCA/GPU combo.So, in fact it's a GPU/PCA combination. Frankly I didn't know that even existed. I replied asking for a simplified schematic, or some dimensions to allow me to model this unit, so here's hoping they are willing to supply that information.

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