On a trip a few weeks ago traveling out of Charlotte (CLT), I took this picture of a vehicle at the airport. Our plane was fueled as we were about to board but due to various factors, boarding didn’t occur until almost five hours later. As we were finally about to board, this vehicle arrived and connected a tube to a port in the vicinity of the fuel input port. My question is this: what was the vehicle doing and what circumstances necessitate the usage of it?

Edit: Although not immediately obvious without zooming in, the yellow pieces visible are the ends of a spool around which the hose is wound. It is not one single large tank as it appears from a distance.

enter image description here

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    $\begingroup$ Maybe adding the airport can help in solving this question. $\endgroup$
    – Roy
    Dec 18, 2019 at 21:35
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    $\begingroup$ Was it a tube for liquid or was it possibly a cable for electricity? $\endgroup$
    – wbeard52
    Dec 18, 2019 at 21:58
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    $\begingroup$ @wbeard52 I’m not sure. It only arrived about 10 minutes before we ended up departing and it left shortly after it arrived. $\endgroup$
    – dalearn
    Dec 18, 2019 at 22:13

3 Answers 3


This looks like an Aircraft Fuel Servicing Cart, which transfers fuel from an underground network to the aircraft. There are two types of vehicles that transfer fuel at larger airports with these fuel networks:

The cart in your picture seems to be the latter of the two (a different model though). You can see the hose that will be connected to the aircraft on the metal staircase. The other hose on the ground connects to the hydrant (hidden behind the aircraft in your image). Your picture shows an Airbus A321, which has the fuel coupling typically located under the right wing (number 11 in the following image):

A321 Ground Servicing Connections
(image source: Airbus A321 Aircraft Characteristics and Airport and Maintenance Planning Document)


Your picture was taken at Charlotte (CLT), which according to this page is equipped with a Jet A Fuel Hydrant Facility. Airports without an underground fuel system will use tank trucks (self-contained fuel trucks) instead:

self-contained fuel truck
(image source: shell.com)

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    $\begingroup$ NOTE TO SELF (and others): Fuel hydrant = Fire hydrant, but they serve VERY different purposes! $\endgroup$
    – FreeMan
    Dec 19, 2019 at 12:25
  • $\begingroup$ Just out of curiosity, is the cart parked in the little white circle because of this? $\endgroup$
    – dalearn
    Dec 19, 2019 at 13:14
  • $\begingroup$ @dalearn I was wondering the same thing, but could not find it in this FAA Advisory Circular or any other document I could find... $\endgroup$
    – Bianfable
    Dec 19, 2019 at 13:22

My guess would be that this is a bowser used for aircraft de-fueling.
Sometimes, very seldom though, aircraft need to be de-fueled to lower the weight for take-off. For example: if the aircraft is refueled for a flight to a destination and back (which is common for various reasons), but for some reason the payload for the first leg increases, the aircraft could be loaded over maximum take-off weight. In that case, a certain amount of fuel could be defueled to lower the weight.
The de-fueling would be done via the same fueling port as refueling, but a normal fuel truck wouldn't necessarily be used.
You can see the fuel hose from the cart connected to the scaffold. The fixed part of the hose in the scaffold is there to facilitate climbing up and attaching the hose to the fuel port under the wing.
Also, there are no other inlets or outlets in the wing near the fueling port.

  • $\begingroup$ Where would the fuel have gone? The fact that it didn’t have any prominent tanks was what originally caught my attention. $\endgroup$
    – dalearn
    Dec 19, 2019 at 3:18
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    $\begingroup$ @dalearn many modern airports don't use fuel bowsers for normal operations but a network of fuel lines running under the ramp that lead to tank farms at the edge of the field. Fueling equipment uses standardised connectors to hook up to those underground lines. $\endgroup$
    – jwenting
    Dec 19, 2019 at 4:28
  • $\begingroup$ What makes you think this was used for de-fueling? 99.9% of the time this would be for re-fueling the aircraft. $\endgroup$
    – Bianfable
    Dec 19, 2019 at 8:07
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    $\begingroup$ @Bianfable at first I looked at this image with my cellphone, couldn't quite figure out what the yellow round thing is on the cart. If it's a tank, it's too small for refueling, only 1-2 tons. It could be a pump and a hose reel, but I don't see a hose connected to the ground well. Also when de-fueling, the fuel would not be directly mixed with the "clean" fuel in the ground tank before it was checked for water etc, so it would be sucked in to a small separate tank. $\endgroup$
    – Sami
    Dec 19, 2019 at 10:28
  • $\begingroup$ @Sami I see, that make sense :) $\endgroup$
    – Bianfable
    Dec 19, 2019 at 10:50

That looks like the ground heating/cooling rig. It is a long flexible hose that connects to the plane (snf the other end connects to a heater or cooler. This way the plane does not have to run the engine or the APU at the gate.


  • $\begingroup$ For some reason, I doubt that this is the purpose. The individual seen in the photo eventually climbed up the metal structure under the wing and plugged the tube into a port of some kind. The cart itself was rather small with no obvious tanks. $\endgroup$
    – dalearn
    Dec 18, 2019 at 22:16
  • $\begingroup$ The cart itself looks like a tank on wheels to me. Unless you are referring to the scaffold looking one on the right side of circle. But the yellow one looks like a tank. $\endgroup$ Dec 18, 2019 at 23:00
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    $\begingroup$ @MichaelHall If you look carefully the yellow pieces are ends to a spool for the hose. From the side, no significant tanks were obvious $\endgroup$
    – dalearn
    Dec 19, 2019 at 3:19
  • $\begingroup$ Gotcha, I couldn't zoom in enough to tell! $\endgroup$ Dec 19, 2019 at 4:59
  • $\begingroup$ @dalearn your first comment would be good info to include in your OP. Plugging something in under the wing is critical info in answering this question with some authority. $\endgroup$
    – FreeMan
    Dec 19, 2019 at 12:28

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