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Airport Ground Procedures...

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In the pursuit of making my simming more 'realistic' :D , I have a few questions about ground procedures...Under what circumstances, other than when there is no availablity, would a large aircraft, such as the LDS 767 use the apu as opposed to external power and external air? Is there a minimum/maximum time, for example, that they might run the apu. When they use external air and power, do they get charged for it by the airport or does the airline have their own gear?If an aircraft is over-nighting at an airport, would they completely power it down, or would it be hooked up to external power and air. How about in the winter if it's very cold?Any and all information regarding ground operations would be really appreciated.Thanks,Adam

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In the US, the airplanes that operate for hire (money) do so under FAA Part 121 (schedule airlines) and part 135 (on demand non-schedule airlines). The FAA issues the operators certificates to operate under either of those parts based on the operation manuals that are submitted by the operators. The manuals are reviewed by the FAA to meet the regulations for certificate issue. A properly written operations manual will address safety first and then consider efficiency for profits sake. Your question depends alot on what the turn around time is and the cost of jet fuel for the APU vs ground based electrical. You can bet the operations manual will have a section covering this and probably a graph showing how long the airplane can remain powered down at a given outside temperature.

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Great explanation Daryll. Thanks. I'll look first in the LDS manual and failing that, I'll see what I can find online.Adam

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I don't have direct answers to all of your questions, though I have read some stories of part 121 operator aircraft A sitting at the gate waiting for the ground power cart to be unhooked from aircraft B of that same airline so that aircraft A may have it's turn using it. So this suggests that in at least some situations they will favor ground power over APU usage, probably for the cost of fuel burn by the APU, etc. I do have a number for friends and acquaintances flying for regional, national, and major airlines that i could inquire with about this if you wish.

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Ok you asked for "anything" Adam.....In Mike Ray's real world 757/767 sim and check ride manual he states on page 120 "Captain After Start Stuff""Before shutting down the APU consider three things"1. Cargo Compartments can no longer be opened2. If Weather is a factor, consider keeping the APU running3. If leg is less than 45 minutes, it's cheaper to keep the APU runningBook is circa 2002 (edition I have is the 2005)Also, did you try AES yet? I hope so, hint hint.....Oliver told me in the Aerosoft forum that he is working on some Canadian Airports (hmmmmm, Al scratches his head)......

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in the jeppesen charts you can find pages which will, depending on airport, tell you what the maximum times for APU use are .. basically we turn it off as soon as external power is available, and we turn it back on shortly before push-back .. if it's very cold or very hot, we turn it on sooner for passengers comfort ..

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Every airline does it differently, they all work out the relative cost/benefit of each and choose the solution which best fits. However, there are a few places where this gets overruled. Swiss airports are notoriously noise sensitive, they make you land and take off in tailwinds (frighteningly high ones too sometimes) and they have steep approaches to keep you as far away from the watchmakers as possible. Equally once you park up they're pretty good at connecting the aircraft up with ground power. If you haven't switched off the APU by the time the dispatcher gets to the flight deck you'd better have a good excuse as she'll go bananas. I've found it's fun to watch but ultimately better to just turn it off. When it's cold they normally connect the ground air too, although they're less keen on turning it on so they need a bit of prompting and coercion to get it going (I've noticed their English suddenly gets really bad and they shrug a lot).The Germans are fairly noise sensitive too and they normally supply the aircraft with ground power quickly and expect you to use it.At Heathrow, ground power is installed on every stand (I think), it only works on half of them and you have to wait for the appropriately qualified and Union approved Ground Power Hooker Upper to come and plug it in. He normally buggers it up and it falls out a few times so don't be too enthusiastic about turning off the APU, lest you plunge your passengers into darkness (have done that a few times, sigh). Nobody seems too worried if you leave the APU running although the good book says you shouldn't. As Heathrow is our base, engineering come and take the planes away for a manicure and bikini wax during the night so it's not uncommon to arrive at the aircraft in the morning to find it in complete darkness. We are not allowed to leave the aircraft with the APU running so sometimes (when the ground power isn't working or the suitably qualified and Union approved Ground Power Hooker Upper is on his tea break) we have to shut the aircraft down. I will admit to getting a curious warm and fuzzy feeling when I switch an Airbus on or off.In some places we go (Milan Linate and Belgrade spring immediately to mind) we aren't offered ground power and we have to leave the APU running. Sounds shocking but at 120Kg/Hr we don't concern ourselves too much.In general when on stand you get ground power and are expected to use it. If the temperatures are uncomfortable (in either direction) you can either use the APU or request ground air to condition the cabin. The ground air tends to be less effective than the APU at making big changes in cabin temperature and depending on where you are you might find it an awful lot of trouble to get it connected and switched on. If we need to condition the cabin we normally just leave the APU on or turn it on early to make it comfortable for the passengers. Otherwise, off at the gate. Just be careful at night, it really doesn't take much for the ground power to come out and if you're switched off the APU you're disembarking passengers using the emergency lights, very professional...Hope this helps,Ian

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Wow! Thanks all you lads for the detailed explanations! Ian, you had me in stitches reading yours. So, from what I gather, I can pretty much make up my own mind - create small scenarios in my head. :( I guess that's what this hobby is mainly about.Al, regarding AES, I have no idea what Oliver is planning. He did contact me about Calgary and Jonathan about Winnipeg but neither of us has heard back from him. I thought I read somewhere that 9 Dragons was getting an AES job. I may be off base, but my guess is that Oliver picks airports that are largely popular and CYYC and Winnipeg likely don't qualify. As soon as I know anything - if I ever do, LOL, I'll be sure to post over at fsnb.Thanks again guys!Adam

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Hi Adam,With my company, as a rule the APU is turned off at the gate. External power is supplied by the bridge power. As for the air, some airports have heat/ac units that are built into the bridge. there are also "portable" Heat/ac and power units that you tow from plane to plane. You would also use these when aircraft are parked on a remote spot. There are, of course, always exceptions. In cold weather we have to keep them heated and there aren't always enough units to go around. In that event, a mechanic has to sit with the plane while the APU is running (almost as expensive as the jet fuel). They are never left running unattended. If you've never seen one, a hotstart on an APU at night can be pretty, uhm, impressive. Cost for anything built into the bridge (power/air) is generally part of the agreement between the airline and the airport authority. Anything portable is all on the individual carrier and they are expensive. A good, refurb'd power unit can go for $50,000 (USD) on the low end.About the overnighters, for the most part they are powered down. They are still plugged in though. Keep in mind that there is quite a bit going on at night. The mechanics will be doing routine maintenance as well as clearing any gripes in the logbook. Lightbulbs, broken coffemaker, that kind of stuff. The planes are also being cleaned and provisioned so we need some lights and air for those folks too. You can figure every aircraft will see from 10 to 15 people working on it throughout the night. A 777 can take 7 people two and a half hours to clean. By 5 am or so, catering is starting to load the pretzels so we need to power up again. Oh, and the cargo doors do open on EXT PWR. Wow, this is long. Sorry, it's late and I was bored. Hope this gives you a bit of insight.Best Regards,JeffInteresting facts: With the old DC-10 when they were still on the line, we almost always ran the APU for air because the external duct is up under the FO's window near the static port and you need a vehicle with a lift to reach it.We try to never run the packs on a 747 in the summer as the exhaust is on the belly, 'bout even with the engines, and temps behind it can reach in excess of 350 deg F.You can simulate lunchtime on mids by jumping into a first class seat on a 777 and poping a movie into the old betamax!Enough. Night.

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I don't mean to hijack this thread but this has been an interesting read - so I would like to see now practical steps/things you could actually do in FS as best as we can.do we shut off the apu and turn on the ext pwr button and then save the situation and say that would be like simulating having ext pwr on all night, etc ??ciao!Brian S

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Hey Jeff,Glad you were bored man! :-lol What a great explanation. I truly appreciate it. It's sounding like the apu is not really used that much. I enjoy making the power and air requests from ground, so I will do that for the most part and use the apu less, maybe on really cold and hot days. I'll be considerate of my cleaners and mechanics, do as Brian suggests, and leave the ext power on when I leave the plane at night.I think it's just great that we can get knowledgeable advice from people in the industry on these forums.Thanks again.Adam

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Thanks for the kind words Adam. I'll try and give you and Brian a little more. Brian, if you want to get real , here it is. I'll try not to get too technical. We'll take it in order. Prior to pushback, the APU will get fired up. Could be 5 min, could be 15+. The bleed air is necessary to start the engines. EXT PWR gets pulled a few minutes before departure. The jetbridges that we have won't move unless the external power cord is retracted. The ground air will get shut off by the ramp crew when the packs are running but, usually gets disconnected about the same time the EXT PWR does. During the push the crew will begin the engine start procedure (You'll hear the packs being turned off). The APU will be powered down during the taxi. The APU usually isn't used on arrival as the engines will continue to provide cool/warm air to the cabin. When the brakes are set at the gate, the number two engine is shut down (This allows the ramp crew to approach and open the cargo doors), and the Fasten seatbelt light is extinguished. The number one engine (the captains side)runs until the bridge is in place and external power is connected. Once connected and tied the Rampie will bang on the side of the plane to let the crew know they have power. I know, you're thinking "well, the EXT PWR light comes on when the power is connected, why do they need to bang on the plane?" Simple answer, it lets the crew know that there should be power. If the indicator light doesn't come on, we know that there is a problem with either the source, the Aircraft electrical system, or the indicator light. So if you want to simulate this, pull into your gate, shutdown number two and leave number one running for anywhere from 45 seconds to a couple of minutes. After that time set the parking brake and the EXT PWR light should come on. Engage EXT PWR and shutdown the remaining engine. Be careful when you do this because in FS your plane can still creep on you. RW practice is, once stopped, the brakes are set and the wheels are chocked. One other point for you, Brian, is that if you try and save the situation, many of the higher end payware aircraft do not save your panel state so, just be aware that it may not be the way it was when you left. Just an FYI, many times when an arriving flight contacts the ramp or gate control, they will be advised if they need the APU at their assigned gate. Sometimes the power on the bridge breaks down.Adam, this might bum you out but it's pretty rare for the flight crew to shut down an aircraft, even after the last flight of the day. They simply have no idea what the plan is for that plane on any given night. They just shut it down normally and we take over from there. Sometimes they'll disconnect the flight surfaces and shut off the efis/eicas stuff, and maybe the hydraulics but, this is more the exception than the rule. One last thing is that it is far more common for a flight crew to change planes for their next flight than it is to stay with the same aircraft over multiple legs.That's it for now as boredom has given way to hunger.All the best,JeffOh BTW, IF it is necessary to utilize the APU on arrival, it will be started up as part of the inbound taxi flow. In that case, Park, set the brakes, make sure the APU is online and shut down both engines at the same time.

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Just for a bit more "real" info, I don't want to take away from anything Jeff has said but here's some differences that are still "real". Not knowing who Jeff flies for or what he flies means it's difficult to tell if the differences are because of the type or just the SOPs.>Prior to>pushback, the APU will get fired up. Could be 5 min, could be>15+. The bleed air is necessary to start the engines. EXT>PWR gets pulled a few minutes before departure. The pushback guys pull the external power (after confirming with us first), anything between -30 and +60 from departure.>The>jetbridges that we have won't move unless the external power>cord is retracted. The ground air will get shut off by the>ramp crew when the packs are running but, usually gets>disconnected about the same time the EXT PWR does. Our external power usually comes from a hole in the ground, sometimes a cart, either way the jetty (or steps) will be removed when they're ready (in fact, if it's steps it's the pushback crew who do it).>During the>push the crew will begin the engine start procedure (You'll>hear the packs being turned off). The APU will be powered>down during the taxi. APU powered down as part of after start checks (unless remote holding).>The APU usually isn't used on arrival>as the engines will continue to provide cool/warm air to the>cabin. The APU is nearly always used on arrival. Often we shut down an engine on the taxi in (to save fuel) so the APU is started shortly after vacating. Don't do this in FS though, the ground handling is so dodgy the aircraft just goes round in circles.>When the brakes are set at the gate, the number two>engine is shut down (This allows the ramp crew to approach and>open the cargo doors), and the Fasten seatbelt light is>extinguished. The number one engine (the captains side)runs>until the bridge is in place and external power is connected. >Once connected and tied the Rampie will bang on the side of>the plane to let the crew know they have power. That is our procedure (roughly) if the APU doesn't work, although we won't let anyone approach the aircraft with the engines running (ground power hooker upper excepted). If it does, as soon as the brakes are on we shut them both down. We don't turn the seat belt signs or beacon off until both engines are shut down though. Once we get the bang from downstairs (that always sounds like they're hitting the aircraft just a bit too hard) we switch to external power. Give it 30 seconds to stabilise then switch off the APU if you're feeling lucky. >Adam, this might bum you out but it's pretty rare for the>flight crew to shut down an aircraft, even after the last>flight of the day. We usually ask someone, if there's no engineer on arrival and the ground power doesn't work, we're shutting it down. If either of those two are present then we'll leave it running. If there's any ambiguity we'll talk to engineering and they'll tell us what they want. We have checks called Secure, which sets the aircraft up to be left unattended but with/without ground power.Likewise on arrival at the aircraft we don't know what fun the engineers have been having so the aircraft gets a thorough preflight (calling engineering if things aren't how they're supposed to be). This can mean the aircraft is cold and dark, not rare but not common either. >One last thing is that it is far more common for a flight crew>to change planes for their next flight than it is to stay with>the same aircraft over multiple legs.Not in out airline, it's about 60/40 that the flight crew will stay with an aircraft when it transits main base. This saves time and is considerably more convenient for all concerned.I'm sure Jeff is correct in everything he has said but I've just highlighted some of the differences that can still be construed as "real".Hope this helps,Ian

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Thanks Ian. That really provides an excellent contrast between US and UK carriers and demonstrates that there really are many different schools of thought when it comes to operating an airline. Just as you pointed out, the info I posted is indeed the SOP and, as presented, refer generally to twin engine jet aircraft as those seem the most widely used in FS. I really try to keep it basic because having been in the industry for 20+ yrs, I sometimes make the mistake of assuming that what is common knowledge to me is common knowledge to everyone. I have a tendancy to unintentionally "put people off" sometimes. I'm sure you can relate to that. One reason I would suggest for the differences in APU usage between the US and EU is that as high as our fuel prices are, they pale in comparison to your costs. Here, the concern is more for cycles on the APU than the fuel. Just to let you all know, I avoid (religiously) mentioning my company. The US is an incredibly litigious society, and I have known people to lose their jobs for posting aviation related topics and mentioning the company. Management contends that we are effectively representing the company and that they could be held liable for any erroneous information. File under: "Sad but True"Thanks again Ian. Great Stuff!Cheers,Jeff

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A big thanks to both of you. Stuff like this really adds to the simulation experience. I have cut and pasted both of your articles onto 2 separate notepad docs. I have not been doing a lot of flying in the UK but my partner in scenery design is from London and he's been encouraging me to do some more flying over there. These notes will be very useful regardless of which region I fly in.It's fun to read this stuff. People like you fellas - and indeed anyone involved in the operations of real-world airlines and GA - should do regular postings - I'm sure they would be well read. Very interesting!Thanks once again.Adam

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