trent1000
Topic Author
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### How Long Can Aircraft Be Stacked?

At major hubs, such as LHR or FRA, how long can aircraft be kept in a holding pattern circling before landing? I realise this probably depends on the aircraft type and where the flight is coming from, but is there any kind of 'priority' system or are planes simply stacked in order until they have to land or are diverted?

EMBQA
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Trent1000 (Thread starter):how long can aircraft be kept in a holding pattern circling before landing?

Until they run out of fuel......
"It's not the size of the dog in the fight, but the size of the fight in the dog"

Starlionblue
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### RE: How Long Can Aircraft Be Stacked?

 Quoting EMBQA (Reply 1):Quoting Trent1000 (Thread starter): how long can aircraft be kept in a holding pattern circling before landing? Until they run out of fuel......

I wanted to say that too   but I think the thread starter meant other constraints and procedures.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

askr
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### RE: How Long Can Aircraft Be Stacked?

Wild guess,, but prubably first come, first served...
Unless someone declares a fuel emergency...
ATC-PL Wanabe :) - 2nd application is in... 11 July...

OPNLguy
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Askr (Reply 3):Wild guess,, but prubably first come, first served... Unless someone declares a fuel emergency...

Pretty much it right there, also I know of situations (internally) where aircraft-A has a hold but not much fuel while our aircraft-B has a hold but has oodles of fuel so we coordinate with ATC and get aircraft-A inbound with no delay while ATC "doubles-up" on aircraft-B who gets twice the delay.

Sometimes, the same coordination is effected from flights of different airlines. More than once I've heard of cases where airLINE-A and airLINE-B are both holding, with one having sufficient gas for the hold and the other not, and the guy/gal with the gas will let the low-gas guy/gal in ahead of them. Some civility does remain...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.

Tristarsteve
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### RE: How Long Can Aircraft Be Stacked?

With modern slot alloocation you rarely go round the hold at LHR more than 2 or 3 times.
When I was at school, we had the Epsom beacon in our grounds.
This was 1960, and usually when we went into school at 0900 there were about 10 aircraft stacked over the beacon, DC7s and Britannias and maybe a Deux-ponts or a Connie.

Don't think stacks are new!

David L
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Tristarsteve (Reply 5):DC7s and Britannias and maybe a Deux-ponts or a Connie.

BA777
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### RE: How Long Can Aircraft Be Stacked?

You can't hold until you run out of fuel, simple! Say the weather was bad and you were waiting for it to improve, you have to be able to leave the hold...fly to your most fuel critical alternate and arrive with final reserves remaining (30 minutes, 1500ft above the airfield in standard conditions)

Starlionblue
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### RE: How Long Can Aircraft Be Stacked?

Of course BA777. It should be "until you run into a fuel critical point that mandates diversion or landing."
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

ba97
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### RE: How Long Can Aircraft Be Stacked?

The stacks at LHR - Is there a vertical limit? When I fly into LHR we do figure 8s cork screwing down sveral laps. I gather you keep piling onto the top of the stack as more come in. Is there a limit and you move to start an outer market stack when full?
there is economy class, business class, first class...then Concorde..pure class

CosmicCruiser
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### RE: How Long Can Aircraft Be Stacked?

 Quoting BA777 (Reply 7):you have to be able to leave the hold...fly to your most fuel critical alternate and arrive with final reserves remaining (30 minutes, 1500ft above the airfield in standard conditions)

not really that's just for flight planning. You can use the fuel as you see fit. What may be prudent is another question. Would you just hold until you had to declare min fuel or an emergency?? Let's hope not. I've left holding more than once because I couldn't rely on ATC to have me on the ground in a reasonable time so I went to the alt and fueled and came back. The first thing you do when you enter holding is determine your amount of fuel you can burn/ amt of time in holding.

BA777
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### RE: How Long Can Aircraft Be Stacked?

Yep very fair point CosmicCruiser, thanks

LHR27C
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Ba97 (Reply 9):The stacks at LHR - Is there a vertical limit? When I fly into LHR we do figure 8s cork screwing down sveral laps. I gather you keep piling onto the top of the stack as more come in. Is there a limit and you move to start an outer market stack when full?

Minimum holding altitude is 7000 feet. This is to ensure separation with departures beneath which are restricted to a max of 6000 until clear of the stacks.

As far as I know there is no upper limit. The highest I remember holding at LHR was FL140 coming into Lambourne when it was particularly clogged up one evening after an emergency landing.
Once you have tasted flight, you will walk the earth with your eyes turned forever skyward

tb727
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Askr (Reply 3):Unless someone declares a fuel emergency...

That's about when it hits the fan because everyone else is gonna call bingo on fuel after you do. Monkey see, monkey do.
Too lazy to work, too scared to steal!

ba97
Posts: 348
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### RE: How Long Can Aircraft Be Stacked?

thanks-- which now make me think - what is the horizontal separation - horizontal being a general reference in that I know it is an incline. I have watched out my window at us criss crossing others at different altitudes. Do you have it set that one is on each leg of the 8in opposite directions?

and then another question- what other airports have figure 8s compared to circles or squares.....? I think I have too much time on my hands to be wondering all this.
there is economy class, business class, first class...then Concorde..pure class

Mastropiero
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### RE: How Long Can Aircraft Be Stacked?

This leads to a question of my own: when did LHR started doing figure 8s instead of squares - rectangles, rather - ? I remember a few years ago, 2002 to be more precise, I flew MAN - LHR and we did rectangles for sure, about 4 or 5 of them.

buckfifty
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Ba97 (Reply 14):thanks-- which now make me think - what is the horizontal separation - horizontal being a general reference in that I know it is an incline. I have watched out my window at us criss crossing others at different altitudes. Do you have it set that one is on each leg of the 8in opposite directions? and then another question- what other airports have figure 8s compared to circles or squares.....? I think I have too much time on my hands to be wondering all this.

 Quoting Mastropiero (Reply 15):This leads to a question of my own: when did LHR started doing figure 8s instead of squares - rectangles, rather - ? I remember a few years ago, 2002 to be more precise, I flew MAN - LHR and we did rectangles for sure, about 4 or 5 of them.

Holding anywhere across the world is always done in elongated oval patterns (racetracks), either using time or distance as a reference for the inbound and outbound legs. There are no figure 8's. The altitude will always remain constant, unless if you're cleared for descent in the hold. However, in that case, the aircraft below you must have vacated the altitude and reached the next one before you can descend that 1000'. No two aircraft can ever, ever hold at the same altitude in the same hold, period.

If you're peering out at Lambourne, it may seem odd that you see planes that may appear to be at the same level as you, just because there could be quite a few of them in the hold. But in actual reality, they're not, just because the visual cues you get may make an aircraft seem closer than they actually are. The minimal vertical separation is always at least 1000', and you will not get any closer than that. And since aircraft are already separated by altitude, there is no horizontal separation criteria.

David L
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Mastropiero (Reply 15):I remember a few years ago, 2002 to be more precise, I flew MAN - LHR and we did rectangles for sure, about 4 or 5 of them.

The last time I was in the hold for LHR was in 2005 and they were definitely still race track shaped then.

 Quoting BuckFifty (Reply 16):There are no figure 8's.

Well, there you go, then. Perhaps the way the hold was entered or left just made it seem like a figure-8.

Mastropiero
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### RE: How Long Can Aircraft Be Stacked?

 Quoting David L (Reply 17): checkmark The last time I was in the hold for LHR was in 2005 and they were definitely still race track shaped then. Quoting BuckFifty (Reply 16): There are no figure 8's. Well, there you go, then. Perhaps the way the hold was entered or left just made it seem like a figure-8.

Thank you for that, I hadn´t heard of figure 8s either but hey, it would take me a day to list all the things I´ve heard of that exist, and probably a whole decade to list all the things I hadn´t heard of that exist too...

LHR27C
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### RE: How Long Can Aircraft Be Stacked?

 Quoting David L (Reply 17):Well, there you go, then. Perhaps the way the hold was entered or left just made it seem like a figure-8.

You can enter the hold with a teardrop entry which might seem a bit like a figure of 8, but to the best of my knowledge this isn't done at LHR generally. What might look a bit like a figure of 8 and is more common is coming off Lambourne for a 27 arrival, aircraft will fly west for a few miles, then do a 180 degree left hand turn back to the east, to slot them into the arrivals stream.
Once you have tasted flight, you will walk the earth with your eyes turned forever skyward

David L
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### RE: How Long Can Aircraft Be Stacked?

 Quoting Mastropiero (Reply 18):I hadn´t heard of figure 8s either

Neither have I. I thought the whole point of the race track path was that it's relatively simple to perform a Rate 1 (?) turn on to a reciprocal heading (though I guess the headings for a figure-8 would be published). Another advantage is that any aircraft in close horizontal proximity are always travelling in the same direction, which would not always be the case at the centre of a figure-8.

ba97
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### RE: How Long Can Aircraft Be Stacked?

thanks all. Most educational. I think the combination of early hours arrival and being half spun on time zone changes, the oval feels more like an extended oval in that short chutes are in the middle of the U turn. I thought it was an "8" is because the turns are not done in one motion but a series of bank level bank level actions (or that is how it appears) and looking down makes you feel like each bank is a greater directional turn. It would make for an interesting photo if one caught a stack of planes in the "race track
there is economy class, business class, first class...then Concorde..pure class

Hywel
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### RE: How Long Can Aircraft Be Stacked?

The longest hold I've experienced was flying into LHR from FRA in 2004... the flight time from FRA to the holding pattern was just under an hour, and then we circled over North London for a further 90 minutes...

The pilot announced it was a good job they'd put enough fuel in for the return journey, otherwise we'd have been diverted to STN. The exceptionally long delay was due to high winds at LHR in which one of the runways had been closed for 45 minutes.

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