Out of interest, what temps where you seeing for FWD and AFT with only the AC? I was parked in Madrid yesterday to test this out, with GPU and AC connected, and it didn't rise above 21 and that was with air temp of 33. I've never found I've had to use the GPU as well as AC for air. Unless I'm reading the temperature gauge wrong, or not waiting enough

 

 

Those things are good for a temp range of about 40-80.

 

That might work in Virginia but not anyplace in Texas LOL.  I passed through DFW one summer night about 11 pm Local and it was still 97 outside. Even the terminals were uncomfortable and the jetways were like ovens still cooling off from the days sun .The aircraft was warm but tolerable (it was not on APU) probably because it had just come in from the stratosphere. Not just the heat (think Phoenix) but the humidity (think Houston) adds to conditioning loads. Regardless, that ground unit is going to be less expensive that anything you stick on an airplane... some rule of nature I think.

That HVAC unit attached to the jetway is much much less expensive to operate than any APU, even a mobile unit is preferable.

 

It's been my experience that external PCA units, either portable or on the jetway, are hit-or-miss at best.  If you do get a unit that happens to put out cold air the hose attached to the aircraft will have three or four kinks in it restricting the airflow. 

Am I right in thinking that the GPU and AC units come at a rent cost from the airport? So is it not a toss up between cost of fuel VS cost of the units? Or is that not the case and they are owned by the airlines anyway? Maybe that's dependent on airport...if you have a base there or not, as it where.

That might work in Virginia but not anyplace in Texas LOL.  I passed through DFW one summer night about 11 pm Local and it was still 97 outside. Even the terminals were uncomfortable and the jetways were like ovens still cooling off from the days sun .The aircraft was warm but tolerable (it was not on APU) probably because it had just come in from the stratosphere. Not just the heat (think Phoenix) but the humidity (think Houston) adds to conditioning loads. Regardless, that ground unit is going to be less expensive that anything you stick on an airplane... some rule of nature I think.

 

That's kinda what I was saying, though.

 

When the temp is 40-80 at IAD, the ground unit will cope pretty well with that (exceptions made for high humidity). Despite that, the ground unit is preferable for its lower cost until just prior to departure time when the APU is all but required to get reasonable temperatures in there. As long as that ground cart is pushing drier air, and the air is moving, it'll take a decent amount of time before it feels stuffy, even if it's not as cool.

 

 

Am I right in thinking that the GPU and AC units come at a rent cost from the airport?

 

Good question.  I assumed that the air and power is provided as a utility that is included in the cost of the gate... never seen meters at the gate.  The airline leases the gate from the airport, which includes the "real property" such as room/air/light and the airline provides people and stuff like computers and maybe vehicles(?).  As a privately owned aircraft, I pay the FBO for the use of facitites through fuel cost but it's extra if I want a ground cart to power my on-board A/C (we have JB Air unit with an electric compressor instead of engine mounted) so we never rent the cart, but I get "free" fresh cookies and a pilot's lounge with recliners, TV and computer terminals.  I would be surprised if the utilities (air/power) were charged to airlines on a pay as you go basis; which means you are paying for it through the gate lease or landing fee used or not.

Am I right in thinking that the GPU and AC units come at a rent cost from the airport? So is it not a toss up between cost of fuel VS cost of the units? Or is that not the case and they are owned by the airlines anyway? Maybe that's dependent on airport...if you have a base there or not, as it where.

 

 

Good question.  I assumed that the air and power is provided as a utility that is included in the cost of the gate... never seen meters at the gate.  The airline leases the gate from the airport, which includes the "real property" such as room/air/light and the airline provides people and stuff like computers and maybe vehicles(?).  As a privately owned aircraft, I pay the FBO for the use of facitites through fuel cost but it's extra if I want a ground cart to power my on-board A/C (we have JB Air unit with an electric compressor instead of engine mounted) so we never rent the cart, but I get "free" fresh cookies and a pilot's lounge with recliners, TV and computer terminals.  I would be surprised if the utilities (air/power) were charged to airlines on a pay as you go basis; which means you are paying for it through the gate lease or landing fee used or not.

 

Depends on the airport. I know that the 'A' gates at IAD were built by ACA/IDE, so modifications to the structure and ramp were more discretionary. When UAX took over the ramp area, that area had gone to MWAA control. MWAA were the ones who added the ground air (the GPU hardpoints were there from ACA), and I remember that if anything ever broke, it had to be routed to them for repair.

 

All that said, I think it was all included in the costs for the gate agreement, as Dan has alluded to.

That sounds about right then, so unless you need more bleed air, which I've heard is possible in places such as Dubai, then there is little reason to use the APU apart from push-back. Also, has been stated, check any charts for European Airports and most will have APU restrictions due to noise, same as a lot have request for only using idle reverse on landing. I don't see these advisories for US airports usually.

 

 

I don't see these advisories for US airports usually.

 

Not usually, though we do have our outliers like SNA and SMO (not sure what the restrictions are out on the west coast, but CA does seem to have a problem with allowing developers to toss up homes next to airports). Not that Leesburg didn't allow the same thing at JYO. You can even see the roughed in streets from where they were going to build before the county stepped in and said "hey now...we know that the land just north of the field isn't ours to zone but knock it off before you shut your own airport down..."

https://www.google.com/maps/@39.0922064,-77.5611022,2474m/data=!3m1!1e3?hl=en

 

So far, we've gotten away with only a "Runway 17 is the calm wind runway" addition to the AWOS broadcast.

Not quite. Those things are good for a temp range of about 40-80. Outside of that, they really don't work too well (at least the ones at IAD didn't, and they were brand new in 2008 when I worked there).

 

Their main purpose is to keep the cabin temps reasonable, which means less time is needed to adjust the temperature when people are about to get on. For some aircraft, an APU wasn't available to cool things off (the SLAAB), so the gate air was all they had, and we'd leave it connected all the way up to immediately before engine turn.

 

Otherwise, it was gate air to keep it "in range" of comfortable (though certainly not comfortable to the average human), and then the APU was brought online just before boarding to get it in the normal comfortable range.

 

This, of course, speaks to the US. I know Europe is far more draconian with APU limits and so on. Then again, we usually have a bit more land buffer between our airports and cities since we have more land to use (in general).

 

 

Not sure how this relates to the discussion. This refers to the fuel control unit for the APU, and not the topic of APU on for air, and the question of on/off for power.

 

 

Aaaaaannnnnd.... Mesa kids used to steal the air hoses attached to our saabs while we were inside grabbing releases/coffee. Don't worry, I'm not bitter!  

Aaaaaannnnnd.... Mesa kids used to steal the air hoses attached to our saabs while we were inside grabbing releases/coffee. Don't worry, I'm not bitter!  

 

Haha - yeah, that's because we all know that if you see YV in the tail number, it means the poor RJ is going to need a huffer to get back out, which means it's also going to need a GPU with one of the engines turning, and the air hose ASAP.

 

You sound like you've been through IAD before... 

Sort of off topic but thought I'd bring it up;

 

I was coming in to EGLL tonght and read through the General pages of the charts, I noticed this;

 

Hierarchy of power sources:

1. Fixed Electrical Ground Power, wherever supplied and servicable

2. GPU, only to be used top FEGP not supported or unit unservicable

3. APU, only to be ysed when neither FEGP nor GPU supplied or the unit is unservicable

 

So large airports, at least this once and can't see it being the only one, have something else other then the GPU. I presume it's a cable from the terminal or from the ground that has a live feed. And is far better as it keeps noise down. I know Heathrow has big problems with noise, so many houses around it so it makes sense. Not a sim issue, and it doesn't support it, but thought it was interesting.

Sort of off topic but thought I'd bring it up;

 

I was coming in to EGLL tonght and read through the General pages of the charts, I noticed this;

 

Hierarchy of power sources:

1. Fixed Electrical Ground Power, wherever supplied and servicable

2. GPU, only to be used top FEGP not supported or unit unservicable

3. APU, only to be ysed when neither FEGP nor GPU supplied or the unit is unservicable

 

So large airports, at least this once and can't see it being the only one, have something else other then the GPU. I presume it's a cable from the terminal or from the ground that has a live feed. And is far better as it keeps noise down. I know Heathrow has big problems with noise, so many houses around it so it makes sense. Not a sim issue, and it doesn't support it, but thought it was interesting.

Most EU and US international airports have FEGP. See the dual plug option on the 777. It's mostly silent except for a high pitched whine. Think of the whine you get when you turn on the fuel pumps in the NGX and lower the pitch about an octave.

 

A GPU cart is more standard at regional/smaller airports without actual jet bridges, or at bizav/GA terminals.

FEGP : Have we run out of three letter acronyms already?  We should call it "shore power" in deference to the rich nautical-base vocabulary that we already use.

FEGP : Have we run out of three letter acronyms already?  We should call it "shore power" in deference to the rich nautical-base vocabulary that we already use.

 

I think some do. We just called it the GPU. If you were referring to the cart version, you added "GPU cart." In reports, to be extra specific, I'd refer to it as "wall mount" or "jetbridge" (depending on the gate) GPU.

 

Usually in a report like this:

A2E: Wall mount GPU broken

A4F: Wall mount GPU broken

(etc etc)