Greetings! I was hoping to gain some more knowledge into how I can keep the cabin/cockpit at a cool temp during the boarding process mainly.
From videos I have seen if it’s 30+ Celsius they will fire up the APU early and keep external power connected. Which I do but the temps (knobs all the way left on cold) just rise up to the 30’s. Making the cabin around 90+ Fahrenheit.
I guess to be more direct… what is a good flow of operations when it comes to hot weather days and how to effectively keep the cabin and cockpit cool until take up (engines running).
Appreciate any help or advice!! Thanks!
In the Fenix I always start cold and dark, and open the cockpit windows.
I complete the safety check, then the Power Up check which includes firing up the APU. Once the APU is online and the bleed pressurized / available, I turn PACK1 and PACK2 off if it is the first flight of the day.
I turn on APU bleed and start the timer, I let the APU bleed run for 3 minutes to blow the dust out of the system, I then continue with the Powering Up checklist.
Once the chrono hits 3 minutes then I turn PACK1 and PACK2 on, and close the cockpit windows. Check the COND page and ensure the cabin is cooling, I continue with the checks and start boarding when ready.
I do the same in the Winter for cold operations to warm the cabin up.
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Thank so much this was answer I was hoping to get!!! I do too start cold and dark and for some reason I just didn’t pay mins to the temp until recent (given simulation I should make sure the temps are correct)
Kinda noonish question, the packs, if the white “off” is illuminated they would be off correct? I think before I’d click those illuminating the “off” they say “Fault” in orange.
Hopefully that question makes sense?
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If they are in fault (orange) it means they are one (were on) when the bleed was closed. If they are white they are off.
Okay that makes sense!! Thank you! Another possible silly question but just wanting to make sure I’m understanding. After you got the APU Bleed running for that 3 minutes, you turn the packs back on (illuminating the orang fault) and close the cockpit windows?
Essentially APU bleed will be engaged the entire boarding process until engines are running?
As you turn PACK1 and PACK2 on, they will change from white (off) to orange (fault) and then to no lights (as they come on).
APU bleed stays on until engine start completed.
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Appreciate your help! This answers questions!!
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So, we don’t tend to turn the packs on and off.
We start the APU, wait 3 minutes, then turn on the APU Bleed. The 3 minute wait allows the APU to stabilize and reduces the chance of APU fumes from entering the air conditioning system. Turning off the packs isn’t necessary since the packs don’t work without some source of bleed air.
Incidentally, this includes HP external air which can power both packs with the Crossbleed open.
This seems to vary between operators, some operator manuals indicate for first flight of the day to turn PACK 1 and 2 off, open bleed, and let run for 3 minutes, then turn on.
For subsequent flights, it then states to start the APU, wait 3, and turn on bleed.
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Yup, there are definitely differences between operators.
I wasn’t so much saying that there is a right or wrong way, just that some operators, like mine, don’t select packs off.
Honestly, compared to say, the 737, cooling down even the 321 usually isn’t a major problem, even in Vegas or Phoenix…unless the plane is heat soaked.
It won’t be super comfortable, but over 90 seems unusually high if the APU has been on for some time. 
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I think that was my main issue… I am not kicking the APU on until like…2minutes maybe before push back.
I am trying to learn real world ops, correct me where I am wrong please, I was under the impression (depending on what airport you’re at) they have ‘nosie pollution’ policy’s and that’s why at times planes are restricted from starting their APU’s early on because with all the planes running them it could become very very loud environment.
So maybe I read something that was talking about a more specific situation. Does that sound right? Appreciate the knowledge you guys are sharing!
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Of course different countries have different regulations, but the reason that US airlines hold off on starting the APU is purely financial. I’m sure that I was sent a bulletin at some point about how much more it costs to run the APU for cooling than using the jetway air. But all I remember was that it was supposedly a lot.
Our manuals generally have us start the APU about 10 minutes prior to pushback. But often in hot weather, the station air just can’t manage the job, and so we start somewhat earlier.
If the station air is down completely, we naturally use the APU full time on the ground.
Interestingly, you’d be surprised at how much difference it makes to open all the gaspers and close all the shades in the aircraft when it’s hot.
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That makes sense!! Now I think about it here in the US, when the APU is not running on the aircraft they got that JetWay air hose hooked up supplying air! Given that is not a feature in MSF, I’ll start utilizing the APU a lot sooner (least once boarding begins)
Don’t want the cabin 30+ Celsius again while they are boarding haha
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