ACN and PCN
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ACN and PCN
A few differences of opinion being expressed in some forums, the subject matter relating mainly to EDI, is it true that a 777-300ER can only operate
from that airport at well below MTOW?
from that airport at well below MTOW?
The PCN value for 06/24 at EDI is 74/R/C/W/T.
The ACN value for a 777-300ER for a Rigid pavement with subgrade C at maximum mass is 109. For mimimum mass the corresponding value is 34.
Therefore, as the ACN value is greater than the PCN value a 777-300ER could not operate at maximum all up mass. To get an ACN value of 74 on that runway would restrict the take-off mass to 610,000 lbs - 167,000 lbs less than the certified maximum mass for a 777-300ER!
So the anwer to your question is YES.
But then again, even if the runway was stronger - it is not long enough! For sea level at ISA a 777-300ER at maximum take-off mass requires a "take-off field length" of just over 3000 metres. 06/24 only has an ASDA of 2614 metres. This would restrict the take-off mass to about 710,000 lbs.
But the runway strength remains the limiting factor!
The ACN value for a 777-300ER for a Rigid pavement with subgrade C at maximum mass is 109. For mimimum mass the corresponding value is 34.
Therefore, as the ACN value is greater than the PCN value a 777-300ER could not operate at maximum all up mass. To get an ACN value of 74 on that runway would restrict the take-off mass to 610,000 lbs - 167,000 lbs less than the certified maximum mass for a 777-300ER!
So the anwer to your question is YES.
But then again, even if the runway was stronger - it is not long enough! For sea level at ISA a 777-300ER at maximum take-off mass requires a "take-off field length" of just over 3000 metres. 06/24 only has an ASDA of 2614 metres. This would restrict the take-off mass to about 710,000 lbs.
But the runway strength remains the limiting factor!
Last edited by Groundloop; 27th Oct 2010 at 11:56.
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GroundLoop.
Not disagreeing with you but isn't there a couple of other factors?
I seem to remember that you can take an extra 10% on top of the PCN for limited operations and also above that the airfield can elect to allow operations with A/C with a higher ACN if they have 'procedure' in place- like regualr runway/pavement checks.
I recall many years ago a 747 operations ex BHX that required a full runway inspection after every landing/departure....usually to pick up bits of runway!!!!
I amy be wrong but seem to recall there are further 'allowances' to be made.
Not disagreeing with you but isn't there a couple of other factors?
I seem to remember that you can take an extra 10% on top of the PCN for limited operations and also above that the airfield can elect to allow operations with A/C with a higher ACN if they have 'procedure' in place- like regualr runway/pavement checks.
I recall many years ago a 747 operations ex BHX that required a full runway inspection after every landing/departure....usually to pick up bits of runway!!!!
I amy be wrong but seem to recall there are further 'allowances' to be made.
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Groundloop said;
The ACN value for a 777-300ER for a Rigid pavement with subgrade C at maximum mass is 109. For [minimum] mass the corresponding value is 34.
Therefore, as the ACN value is greater than the PCN value a 777-300ER could not operate at maximum all up mass. To get an ACN value of 74 on that runway would restrict the take-off mass to 610,000 lbs - 167,000 lbs less than the certified maximum mass for a 777-300ER!
The ACN value for a 777-300ER for a Rigid pavement with subgrade C at maximum mass is 109. For [minimum] mass the corresponding value is 34.
Therefore, as the ACN value is greater than the PCN value a 777-300ER could not operate at maximum all up mass. To get an ACN value of 74 on that runway would restrict the take-off mass to 610,000 lbs - 167,000 lbs less than the certified maximum mass for a 777-300ER!
Or perhaps it's not that simple?
One other limiting factor might be the PCN of taxiways Lima and /or Mike which link the SE Apron to Taxiway Alpha. The NATS info for EDI ( NATS | AIS - Home ) doesn't give a strength for taxiways Lima and Mike but they are effectively part of Runway 12/30 which has a PCN of 31F/C/X/T. Stand 6A was eliminated about a year ago and, since then, Stand 17 on the SE apron is now the only one almost large enough to take a 773ER (the stand is slightly too short but this was tolerated when the AF 773ER visited for the rugby internationals earlier this year). I suspect that taxiway Lima is stronger than 12/30, otherwise it wouldn’t even support a B738 at MTOW but I can’t find any evidence to say what the actual PCN is.
What would it take to strengthen the runway, aprons and taxiways at EDI? Would they need to dig out the entire pavement and subgrade and start again or would an extra layer of concrete on top be sufficient? If the latter, I'm surprised they didn't strengthen the runway when it was resurfaced not so long ago.
Last edited by Porrohman; 29th Oct 2010 at 02:57.
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" I'm surprised they didn't strengthen the runway when it was resurfaced not so long ago."
Perhaps they didn't want a higher runway classification?
Perhaps they didn't want a higher runway classification?
I'm just an interested frequent flyer so I apologise if I'm talking nonsence but are you sure about the 34, the 109 and the 610,000lbs Groundloop?
http://www.boeing.com/commercial/airports/acaps/777rsec7.pdf
Page 150 has the ACN values and Page 156 has the chart for calculating the take-off mass for a given limiting PCN value.
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It is interesting looking at places like Corfu and Zakinthos, they aren't man enough for an A321 WRT PCN, but stilll we operate into them with an A321. The get out is that ops can proceed with agreement with the airport operator and airline.
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Groundloop said;
Page 150 has the ACN values and Page 156 has the chart for calculating the take-off mass for a given limiting PCN value.
Page 150 has the ACN values and Page 156 has the chart for calculating the take-off mass for a given limiting PCN value.
Assuming that Taxiway Lima and/or Mike at EDI are not a limiting factor, the maximum ramp weight of a 773ER at EDI, based on the apron strength of 72R/C/W/T would be about 595,000lbs which would give a maximum take-off weight at EDI of slightly less than that, allowing for fuel burn during start-up and taxiing.
Looking at the Boeing payload /range and runway charts at http://www.boeing.com/commercial/air...s/777rsec3.pdf for a 773ER with GE90-115BL engines on a standard day with zero winds (see page 38) would give a range of just under 1,500nm at MZFW. What would the range be with a typical economic commercial payload? I'm guessing about 3,000nm, maybe less?
The charts on page 48 show that, on a standard day, a 6,000ft runway would be required at that weight (EDI is 100ft/110ft AMSL) so, as you said, PCN not runway length is the limiting factor.
If it transpires that the PCNs on Taxiway Lima and Mike at EDI are the same as runway 12/30 (31F/C/X/T) then that would be a more significant limiting factor. If anyone knows the PCNs for these taxiways please let me know.
Comparing these figures with GLA where the PCN is 65R/B/W/T, the maximum ramp weight there would be 660,000lbs requiring a take off run of about 7,300ft and giving a range at MZFW of about 3,050nm.
I did the same calculations for NCL where the PCN is 73F/C/W/T and airfield elevation is 266ft. The maximum ramp weight there would be 685,000lbs requiring a take-off run of about 8,000ft, but as the runway is only 7,641ft long the maximum take-off weight would be limited by the runway length rather than the PCN. Looking at the performance charts, it looks like the maximum take-off weight at NCL would be about 675,000lbs.
Although PCN rather than runway length is the limiting factor at GLA, and runway length is the limiting factor at NCL, it’s easy to see why Emirates chose GLA and NCL over EDI. The ability to lift an extra 65,000lbs and 80,000lbs of fuel/payload from GLA and NCL respectively is a significant difference.
Some final questions if I may. If the PCN and ACN indicate a particular maximum weight, under what circumstances can that be exceeded, by how much, how often and on whose authority? I have the impression that PCNs are regularly exceeded at EDI so it then becomes impossible to establish what limitations apply to payload/range for an aircraft from EDI.
Last edited by Porrohman; 29th Oct 2010 at 15:33.
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Answering my own question, I think the following would be the payload/range figures from EDI in a 777-300ER (NB. the figures in brackets below indicate the maximums if there were no PCN or runway length limitations).
Boeing 777-300ER
Max ramp weight at EDI; 595,000lbs (775,000lbs)
Fuel/payload reduction from EDI; 180,000lbs i.e. 49%.
Range from EDI with max payload; 1,350nm (5,700nm).
Range from EDI with 364 pax and no cargo; 2,650nm (6,850nm).
Range from EDI with 364 pax and 30,000lbs of cargo; 1,800nm (5,850nm).
ACN empty; 34. ACN at MTOW; 109 (on rigid pavement with low strength subgrade)
Payload/range from EDI is currently PCN limited; a B773ER only requires 5,920ft runway at this weight (runway is 8,400ft long).
Source data; Boeing: Commercial Airplanes - Commercial Aviation Services - Flight Operations - Airport Technology - Airplane Characteristics for Airport Planning and NATS | AIS - Home .
Based on these figures, I can't see any airline being able to operate 777-300ERs on long-range flights from EDI unless the PCNs are significantly upgraded. How much work would that require? Would an extra layer of concrete on top fix the problem or would they have to install a higher strength subgrade first? How could work such as this be carried out without disrupting operations at the airport too much?
I'm still wondering whether the PCNs of Taxiways Lima and Mike at EDI are a further impediment to long range operations. These taxiways are effectively part of runway 12/30 which has a PCN of 31F/C/X/T which is far weaker than the passenger aprons (72R/C/W/T), Taxiway Alpha (74R/C/W/T) and Runway 06/24 (74R/C/W/T). If anyone knows the PCNs for Taxiways Lima and Mike, please let me know. They are not mentioned in the NATS data for EDI. If they are 31F/C/X/T, and given that the only stands capable of taking anything bigger than a 767-300 at EDI need to use these taxiways to reach the SE Apron, then the strength of these taxiways would reduce the payload range figures I calculated above by a significant extent unless the main apron is altered to cater for larger wide-bodied aircraft. The only place I can see where this might be possible would be to create a stand between stands 11 and 14.
Can anyone explain what criteria are used to determine whether a PCN can be exceeded? Block 33 at the SE end of Runway 12/30 is often used for parking widebodies, but perhaps just when they are empty (i.e. when the ACN is much lower)? There is however at least one situation where I know that an ACN has exceeded the PCN of 12/30 by a wide margin. Back in 2001/2 an AN124 at Block 33 was loaded with over 100 tons of drilling equipment and fuel. It was so heavy that it needed to depart at night when the air temp was lower. That must have exceeded the PCN by a wide margin but presumably the multi-wheeled undercarriage was deemed to spread the weight sufficiently that the airfield and aircraft operators deemed that it was acceptable?
Another possibility is that runway 12/30 at EDI is, in reality, much stronger than has been indicated on paper and that the declared PCN has been artificially reduced to limit the size of aircraft that are permitted to takeoff and land on that runway (because of the proximity of housing and related noise considerations). If so, perhaps EDI is quite happy to allow aircraft with a much higher ACN to taxi and park there on a case by case basis? I seem to recall reading that EDI was one of the V-Bomber dispersal airfields during the cold war so runway 12/30 must presumably have been much stronger than 31F/C/X/T back then.
Boeing 777-300ER
Max ramp weight at EDI; 595,000lbs (775,000lbs)
Fuel/payload reduction from EDI; 180,000lbs i.e. 49%.
Range from EDI with max payload; 1,350nm (5,700nm).
Range from EDI with 364 pax and no cargo; 2,650nm (6,850nm).
Range from EDI with 364 pax and 30,000lbs of cargo; 1,800nm (5,850nm).
ACN empty; 34. ACN at MTOW; 109 (on rigid pavement with low strength subgrade)
Payload/range from EDI is currently PCN limited; a B773ER only requires 5,920ft runway at this weight (runway is 8,400ft long).
Source data; Boeing: Commercial Airplanes - Commercial Aviation Services - Flight Operations - Airport Technology - Airplane Characteristics for Airport Planning and NATS | AIS - Home .
Based on these figures, I can't see any airline being able to operate 777-300ERs on long-range flights from EDI unless the PCNs are significantly upgraded. How much work would that require? Would an extra layer of concrete on top fix the problem or would they have to install a higher strength subgrade first? How could work such as this be carried out without disrupting operations at the airport too much?
I'm still wondering whether the PCNs of Taxiways Lima and Mike at EDI are a further impediment to long range operations. These taxiways are effectively part of runway 12/30 which has a PCN of 31F/C/X/T which is far weaker than the passenger aprons (72R/C/W/T), Taxiway Alpha (74R/C/W/T) and Runway 06/24 (74R/C/W/T). If anyone knows the PCNs for Taxiways Lima and Mike, please let me know. They are not mentioned in the NATS data for EDI. If they are 31F/C/X/T, and given that the only stands capable of taking anything bigger than a 767-300 at EDI need to use these taxiways to reach the SE Apron, then the strength of these taxiways would reduce the payload range figures I calculated above by a significant extent unless the main apron is altered to cater for larger wide-bodied aircraft. The only place I can see where this might be possible would be to create a stand between stands 11 and 14.
Can anyone explain what criteria are used to determine whether a PCN can be exceeded? Block 33 at the SE end of Runway 12/30 is often used for parking widebodies, but perhaps just when they are empty (i.e. when the ACN is much lower)? There is however at least one situation where I know that an ACN has exceeded the PCN of 12/30 by a wide margin. Back in 2001/2 an AN124 at Block 33 was loaded with over 100 tons of drilling equipment and fuel. It was so heavy that it needed to depart at night when the air temp was lower. That must have exceeded the PCN by a wide margin but presumably the multi-wheeled undercarriage was deemed to spread the weight sufficiently that the airfield and aircraft operators deemed that it was acceptable?
Another possibility is that runway 12/30 at EDI is, in reality, much stronger than has been indicated on paper and that the declared PCN has been artificially reduced to limit the size of aircraft that are permitted to takeoff and land on that runway (because of the proximity of housing and related noise considerations). If so, perhaps EDI is quite happy to allow aircraft with a much higher ACN to taxi and park there on a case by case basis? I seem to recall reading that EDI was one of the V-Bomber dispersal airfields during the cold war so runway 12/30 must presumably have been much stronger than 31F/C/X/T back then.
Last edited by Porrohman; 10th Nov 2010 at 13:40.
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EDI 06/24 74/R/C/W/T Grooved Asphalt
Parallel taxiway 06/24: Width: 23 m. Surface: Asphalt Strength: 74/R/C/W/T
Terminal Stands: Surface: Concrete Strength: 72/R/C/W/T
My interpretation is that the runway has an asphalt overlay, on top of a concrete (rigid) pavement. If I sharpen the pencil and calculate deeply, the weight limit is closer to 605,000 lb or 274.4 t (rather than 610,000 lbs).
In response to earlier questions, no tyre pressure reduction is done on these or most aircraft nowadays – it dropped out of fashion as an option after the 1980's once the old runways built for propeller aircraft had been all been strengthened.
That pavement rating at EDI 06/24 is good enough for fully laden Boeing 747-400 territory. Gee guys – that's pretty generous already. Running a Boeing 747 off that short 2556m long runway is almost over-servicing the airport.
The AN124 with its 100+ tonnes payload – well the ACN is 73 at maximum takeoff weight, so no concession was needed (the Russians build very pavement-friendly aircraft).
Overload guidance
CAP 168 gives:
I have an unreferenced guide, purportedly about UK practice, that an overload by an aircraft with an ACN of more than 10 percent but not exceeding 25 percent of the reported PCN requires regular inspections of the pavement by a competent person and there should be an immediate curtailment of such overload operations as soon as distress becomes evident. [It doesn't say so directly, but only a few operations would be permitted at this level]. An overload by aircraft with an ACN great than 25 percent but not exceeding 50 percent of the reported ACN may be undertaken under special circumstances including scrutiny of available pavement construction records and test data by a qualified pavement engineer; and a thorough inspection by a pavement. [It doesn't say so directly, but this is more the one-off event]. This is a very reasonable approach to overloads, and I use that myself (even if I can't find the reference).
Having said all that, the 777-300ER (and A340-600) are particularly nasty beasts in terms of pavement loading, and they do damage seemingly disproportionate to their size. There is a growing body of opinion that for these particular aircraft, all manner of concessions need to be rethought, limited or withdrawn (including even the various equivalencies in pavement thicknesses). So discussions about permitting overloads for the 777-300ER should be appropriately constrained, and only very small overloads permitted.
As an aside, but I'm not going to let this one get past unmentioned because of the many frustrations it has caused me in the past, as tom775257 noted earlier:
Ah, Greek Airports. The finest overload that money can buy.
Cost to upgrade Edinburgh
The EDI pavement PCN rating has been done on a technical basis (the "T" in the rating), so I'm guessing the EDI probably have a reasonable idea of what is needed and the cost. I can give a ballpark estimate, but it is very much subject to adjustment based on the actual pavement. To move the runway rating for the 777-300ER from 274.4 tonnes to 352.2 tonnes, simplistically needs another 200mm of asphalt. The runway, parallel taxiway, stub taxiways and some of the apron all need to be overlaid. The cost will be loaded for (a) night work, constructing in limited hours to MOWP, temporary ramps and grooving, etc; (b) many runway lighting changes and re-cabling, matching in the geometric levels at all shoulders and all intersections, new markings; and (c) compliance with noise, environmental, and all manner of constraints.
I'm guessing that the whole project might run to GBP150 per tonne of laid asphalt. That would put the project at about GBP 15 million. However these projects can take on a life of their own (especially some of the UK ones I've seen), so figures going skywards up to GBP 50 million could be thrown around.
Cheers
Overrun
Parallel taxiway 06/24: Width: 23 m. Surface: Asphalt Strength: 74/R/C/W/T
Terminal Stands: Surface: Concrete Strength: 72/R/C/W/T
My interpretation is that the runway has an asphalt overlay, on top of a concrete (rigid) pavement. If I sharpen the pencil and calculate deeply, the weight limit is closer to 605,000 lb or 274.4 t (rather than 610,000 lbs).
In response to earlier questions, no tyre pressure reduction is done on these or most aircraft nowadays – it dropped out of fashion as an option after the 1980's once the old runways built for propeller aircraft had been all been strengthened.
That pavement rating at EDI 06/24 is good enough for fully laden Boeing 747-400 territory. Gee guys – that's pretty generous already. Running a Boeing 747 off that short 2556m long runway is almost over-servicing the airport.
The AN124 with its 100+ tonnes payload – well the ACN is 73 at maximum takeoff weight, so no concession was needed (the Russians build very pavement-friendly aircraft).
Overload guidance
CAP 168 gives:
12.4.1 Individual aerodrome authorities are free to decide their own criteria for permitting overload operations as long as pavements remain safe for use by aircraft. The PCN value does include a safety factor so that a 10% increase of ACN over PCN is generally acceptable for pavements that are well consolidated and in good condition.
Having said all that, the 777-300ER (and A340-600) are particularly nasty beasts in terms of pavement loading, and they do damage seemingly disproportionate to their size. There is a growing body of opinion that for these particular aircraft, all manner of concessions need to be rethought, limited or withdrawn (including even the various equivalencies in pavement thicknesses). So discussions about permitting overloads for the 777-300ER should be appropriately constrained, and only very small overloads permitted.
As an aside, but I'm not going to let this one get past unmentioned because of the many frustrations it has caused me in the past, as tom775257 noted earlier:
places like Corfu and Zakinthos, they aren't man enough for an A321 WRT PCN, but still we operate into them with an A321.
Cost to upgrade Edinburgh
The EDI pavement PCN rating has been done on a technical basis (the "T" in the rating), so I'm guessing the EDI probably have a reasonable idea of what is needed and the cost. I can give a ballpark estimate, but it is very much subject to adjustment based on the actual pavement. To move the runway rating for the 777-300ER from 274.4 tonnes to 352.2 tonnes, simplistically needs another 200mm of asphalt. The runway, parallel taxiway, stub taxiways and some of the apron all need to be overlaid. The cost will be loaded for (a) night work, constructing in limited hours to MOWP, temporary ramps and grooving, etc; (b) many runway lighting changes and re-cabling, matching in the geometric levels at all shoulders and all intersections, new markings; and (c) compliance with noise, environmental, and all manner of constraints.
I'm guessing that the whole project might run to GBP150 per tonne of laid asphalt. That would put the project at about GBP 15 million. However these projects can take on a life of their own (especially some of the UK ones I've seen), so figures going skywards up to GBP 50 million could be thrown around.
Cheers
Overrun
Last edited by OverRun; 11th Nov 2010 at 04:31.
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Thanks for taking the time to reply in such detail once again OverRun. It has greatly helped my understanding of this subject.
As background to my questions, EDI has declared its desire to attract long-haul operations and, as a frequent flyer, I'll be pleased if they succeed in that ambition. I'm just concerned that some aspects of the infrastructure might not yet support that ambition. I had previously wondered why the likes of Emirates hadn't introduced flights from EDI to DXB, but it's now clear why they could not operate from EDI with a sensible payload. Of course they might have chosen Glasgow and Newcastle for other reasons but the PCNs do not help EDI to attract Boeing 777-300ER operators.
EDI currently has just 3 stands that are larger than 767-300 size and these are all on the SE apron. To reach the SE apron it is necessary to use taxiway Lima or Mike. Both of these taxiways are effectively part of runway 12/30 which has a PCN of 31/F/C/X/T. If Lima and Mike are also 31/F/C/X/T then I can't see how long-haul flights can depart from the SE apron as the ACNs are likely to be around twice the PCN of these taxiways. (See; NATS | AIS - Home for the layout of the airfield and taxiways.)
Given the current ACN/PCN limitations, and the fact that the runway could be upgraded by adding another 200mm of asphalt, I find it surprising EDI didn't upgrade 06/24 when they resurfaced it two years ago. Or maybe they did but they haven't updated the technical analysis yet? Do airport operators sometimes leave the surface to "bed-down" for a while before they carry out a technical analysis and declare a higher PCN?
I agree with you for 06/24. The slightly lower 595,000lbs figure I calculated was based on the 72R/C/W/T rating on the aprons. Or maybe I'm just reading the Boeing charts slightly differently to you as the resolution is not that great. We're near enough the same answer anyway.
I looked at the ACN/PCN and runway length limitations at EDI for a range of aircraft and concluded that the PCN limits operations of many aircraft from EDI more than the runway length does. The undercarriage arrangement of a 747 is kinder to pavements than the more recent long-haul twin-jets. I don't think 747s are likely to operate from EDI in the foreseeable future. More likely would be A330 / A350 / B787 / B777 if the PCNs would support them. Unfortunately, the ACNs of all but the A330 are a fair bit higher at MTOW than the current PCNs at EDI which will therefore limit their potential payload/range. I've added some examples at the end of this post.
The issue with the AN124 was not the PCN of the take-off runway, but the PCN of the runway they parked it on. Block 33, where it was parked, is the turnaround area at the SE end of runway 12/30. That runway has a PCN of 31F/C/X/T. To reach 06/24 the AN124 had to taxi the whole length of 12/30. The ACN of an AN124 at MTOW on that surface is 77. I'm not sure what the all-up weight of the aircraft was on departure but I expect the ACN was more than double the PCN of 12/30. This makes me wonder whether the declared PCN of 12/30 is perhaps a lot less than the actual PCN, hence my comments about them perhaps reducing the declared PCN to restrict the size of aircraft allowed to take-off and land on that runway.
Examples of payload/range limitations from EDI;
NB. The figures in brackets are those that would apply if there were no PCN or runway length limitations. All figures are based on data from the Boeing website and are based on the apron PCN of 72R/C/W/T rather than the runway PCN of 74R/C/W/T.
Boeing 787-8
Fuel/payload reduction from EDI; 53,500lbs (20%).
ACN empty; 40. ACN at MTOW; 84.
Boeing hasn't published any payload/range or runway performance figures for the 787-8 yet but it is already clear, based on the preliminary ACN charts they have published, that payload/range from EDI will be limited by the PCN of the apron, taxiways and the runway unless they are all strengthened.
Boeing 777-300ER
Fuel/payload reduction from EDI; 180,000lbs (49%).
Range from EDI with max payload; 1,350nm (5,700nm).
Range from EDI with 364 pax and no cargo; 2,650nm (6,850nm).
Range from EDI with 364 pax and 30,000lbs of cargo; 1,800nm (5,850nm).
ACN empty; 34. ACN at MTOW; 109
Payload/range from EDI is currently PCN limited; only requires 5,920ft runway at this weight.
Boeing 777F (115)
Fuel/payload reduction from EDI; 161,000lbs (36%).
Range from EDI with max payload; 850nm (5,800nm).
Range from EDI with 180,000lbs of cargo; 2,550nm (6,300nm).
ACN empty; 27. ACN at MTOW; 105.
Payload/range from EDI is currently PCN limited; only requires 5,850ft runway at this weight.
Boeing 777-200LR (115)
Fuel /payload reduction from EDI; 161,000lbs (36%).
Range from EDI with max payload; 3,600nm (7,650nm).
Range from EDI with 266 pax and no cargo; 5,800nm (9,500nm).
Range from EDI with 266 pax and 30,00lbs of cargo; 4,600nm (8,450nm).
ACN empty; 27. ACN at MTOW; 105.
Payload/range from EDI is currently PCN limited; only requires 5,700ft runway at this weight.
Boeing 777-300 (98)
Fuel/payload reduction from EDI; 78,000lbs (25%).
Range from EDI with max payload; 1,750nm (3,700nm).
Range from EDI with 364 pax and no cargo; 3,950nm (5,700nm).
Range from EDI with 364 pax and 30,000lbs of cargo; 2,900nm (4,700nm).
ACN empty; 33. ACN at MTOW; 88.
Payload/range from EDI is currently PCN limited; only requires 8,100ft runway at this weight.
Boeing 777-200ER
Fuel/payload reduction from EDI; 51,000lbs (15%).
Range from EDI with max payload; 4,100nm (5,750nm).
Range from EDI with 266 pax and no cargo; 6,700nm (8,400nm).
Range from EDI with 266 pax and 30,000lbs of cargo; 5,350nm (7,200nm).
ACN empty; 26. ACN at MTOW; 82.
Payload/range from EDI is currently PCN limited; only requires 8,250ft runway at this weight.
Boeing 747-400ER (GE)
Fuel/payload reduction from EDI; 77,000lbs (15%).
Range from EDI with max payload; 4,850nm (6,300nm).
Range from EDI with 416 pax and no cargo; 6,600nm (7,850nm).
Range from EDI with 416 pax and 40,000lbs of cargo; 5,700nm (6,900nm).
ACN empty; 23. ACN at MTOW; 81.
Payload/range from EDI is currently limited equally by runway length and PCN but if runway is extended it would then be limited by PCN unless the runway, taxiways and aprons are strengthened.
Boeing 747-8I
Fuel/payload reduction from EDI; 138,000lbs (29%).
Range from EDI with max payload; 3,750nm (6,200nm).
Range from EDI with 467 pax and no cargo; 6,750nm (8,800nm).
Range from EDI with 467 pax and 45,000lbs of cargo; 6,200nm (8,600nm).
ACN empty; 35. ACN at MTOW; 88.
Payload/range from EDI is currently PCN limited; only requires 7,700ft runway at this weight. NB. These figures are based on preliminary Boeing data.
Airbus' data is less detailed than Boeing's, but indications are that the A330 is only very slightly limited by the PCNs at EDI. The A350 payload/fuel reduction is likely to be around the same as the B787 based on preliminary ACN data from Airbus i.e. somewhere around 20% depending on version.
As background to my questions, EDI has declared its desire to attract long-haul operations and, as a frequent flyer, I'll be pleased if they succeed in that ambition. I'm just concerned that some aspects of the infrastructure might not yet support that ambition. I had previously wondered why the likes of Emirates hadn't introduced flights from EDI to DXB, but it's now clear why they could not operate from EDI with a sensible payload. Of course they might have chosen Glasgow and Newcastle for other reasons but the PCNs do not help EDI to attract Boeing 777-300ER operators.
EDI currently has just 3 stands that are larger than 767-300 size and these are all on the SE apron. To reach the SE apron it is necessary to use taxiway Lima or Mike. Both of these taxiways are effectively part of runway 12/30 which has a PCN of 31/F/C/X/T. If Lima and Mike are also 31/F/C/X/T then I can't see how long-haul flights can depart from the SE apron as the ACNs are likely to be around twice the PCN of these taxiways. (See; NATS | AIS - Home for the layout of the airfield and taxiways.)
Given the current ACN/PCN limitations, and the fact that the runway could be upgraded by adding another 200mm of asphalt, I find it surprising EDI didn't upgrade 06/24 when they resurfaced it two years ago. Or maybe they did but they haven't updated the technical analysis yet? Do airport operators sometimes leave the surface to "bed-down" for a while before they carry out a technical analysis and declare a higher PCN?
My interpretation is that the runway has an asphalt overlay, on top of a concrete (rigid) pavement. If I sharpen the pencil and calculate deeply, the weight limit is closer to 605,000 lb or 274.4 t (rather than 610,000 lbs).
That pavement rating at EDI 06/24 is good enough for fully laden Boeing 747-400 territory. Gee guys – that's pretty generous already. Running a Boeing 747 off that short 2556m long runway is almost over-servicing the airport.
The AN124 with its 100+ tonnes payload – well the ACN is 73 at maximum takeoff weight, so no concession was needed (the Russians build very pavement-friendly aircraft).
Examples of payload/range limitations from EDI;
NB. The figures in brackets are those that would apply if there were no PCN or runway length limitations. All figures are based on data from the Boeing website and are based on the apron PCN of 72R/C/W/T rather than the runway PCN of 74R/C/W/T.
Boeing 787-8
Fuel/payload reduction from EDI; 53,500lbs (20%).
ACN empty; 40. ACN at MTOW; 84.
Boeing hasn't published any payload/range or runway performance figures for the 787-8 yet but it is already clear, based on the preliminary ACN charts they have published, that payload/range from EDI will be limited by the PCN of the apron, taxiways and the runway unless they are all strengthened.
Boeing 777-300ER
Fuel/payload reduction from EDI; 180,000lbs (49%).
Range from EDI with max payload; 1,350nm (5,700nm).
Range from EDI with 364 pax and no cargo; 2,650nm (6,850nm).
Range from EDI with 364 pax and 30,000lbs of cargo; 1,800nm (5,850nm).
ACN empty; 34. ACN at MTOW; 109
Payload/range from EDI is currently PCN limited; only requires 5,920ft runway at this weight.
Boeing 777F (115)
Fuel/payload reduction from EDI; 161,000lbs (36%).
Range from EDI with max payload; 850nm (5,800nm).
Range from EDI with 180,000lbs of cargo; 2,550nm (6,300nm).
ACN empty; 27. ACN at MTOW; 105.
Payload/range from EDI is currently PCN limited; only requires 5,850ft runway at this weight.
Boeing 777-200LR (115)
Fuel /payload reduction from EDI; 161,000lbs (36%).
Range from EDI with max payload; 3,600nm (7,650nm).
Range from EDI with 266 pax and no cargo; 5,800nm (9,500nm).
Range from EDI with 266 pax and 30,00lbs of cargo; 4,600nm (8,450nm).
ACN empty; 27. ACN at MTOW; 105.
Payload/range from EDI is currently PCN limited; only requires 5,700ft runway at this weight.
Boeing 777-300 (98)
Fuel/payload reduction from EDI; 78,000lbs (25%).
Range from EDI with max payload; 1,750nm (3,700nm).
Range from EDI with 364 pax and no cargo; 3,950nm (5,700nm).
Range from EDI with 364 pax and 30,000lbs of cargo; 2,900nm (4,700nm).
ACN empty; 33. ACN at MTOW; 88.
Payload/range from EDI is currently PCN limited; only requires 8,100ft runway at this weight.
Boeing 777-200ER
Fuel/payload reduction from EDI; 51,000lbs (15%).
Range from EDI with max payload; 4,100nm (5,750nm).
Range from EDI with 266 pax and no cargo; 6,700nm (8,400nm).
Range from EDI with 266 pax and 30,000lbs of cargo; 5,350nm (7,200nm).
ACN empty; 26. ACN at MTOW; 82.
Payload/range from EDI is currently PCN limited; only requires 8,250ft runway at this weight.
Boeing 747-400ER (GE)
Fuel/payload reduction from EDI; 77,000lbs (15%).
Range from EDI with max payload; 4,850nm (6,300nm).
Range from EDI with 416 pax and no cargo; 6,600nm (7,850nm).
Range from EDI with 416 pax and 40,000lbs of cargo; 5,700nm (6,900nm).
ACN empty; 23. ACN at MTOW; 81.
Payload/range from EDI is currently limited equally by runway length and PCN but if runway is extended it would then be limited by PCN unless the runway, taxiways and aprons are strengthened.
Boeing 747-8I
Fuel/payload reduction from EDI; 138,000lbs (29%).
Range from EDI with max payload; 3,750nm (6,200nm).
Range from EDI with 467 pax and no cargo; 6,750nm (8,800nm).
Range from EDI with 467 pax and 45,000lbs of cargo; 6,200nm (8,600nm).
ACN empty; 35. ACN at MTOW; 88.
Payload/range from EDI is currently PCN limited; only requires 7,700ft runway at this weight. NB. These figures are based on preliminary Boeing data.
Airbus' data is less detailed than Boeing's, but indications are that the A330 is only very slightly limited by the PCNs at EDI. The A350 payload/fuel reduction is likely to be around the same as the B787 based on preliminary ACN data from Airbus i.e. somewhere around 20% depending on version.
Last edited by Porrohman; 11th Nov 2010 at 12:37.
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Porrohman,
I think your answer lies somewhere in the holy trinity of airport engineering, aircraft performance engineering and airline economics.
I don’t often encounter runways which impose no limitations in terms of strength or length (excepting the Middle Eastern bedlam of Sheiks striving for the biggest and best). In the UK, most runways impose some compromise, and EDI is no exception. The essence of the answer on any runway upgrade is therefore to work out what traffic there will be (i.e. how many punters), and where they are going (route length), and that will dictate the aircraft takeoff weight and takeoff length.
I was a bit surprised when I checked the population of Edinburgh, and it showed as only 450,000. And 9 million pax/year. From the airline economist's viewpoint, that is at the bottom end of traffic needed for a decent sized airport, and I would think it might even be getting below that needed to have commercially viable B777-300ER operations on a daily basis. There is not much scope for bigger planes at smaller airports because it drops the frequencies down and the punters prefer higher frequencies. The medium sized 250 pax A330-200 is better fit at a place like Edinburgh than a 350 pax B777-300ER.
The issue of route length is a key one. The B777-300ER is a very long range plane – the map below shows its maximum range from EDI. That is pretty well non-stop anywhere in the civilised world (except Australia and New Zealand and we all know that the Antipodes is not part of the civilised world). I don’t think the traffic or market is there for those extreme range operations from EDI.
What is more likely to be viable is a medium range operation, 4000 NM. The next map shows that this gets to the Middle East (and thus by connection to anywhere else in the world), it gets direct to most of the USA and Canada, all of Europe, most of Africa, and some of Asia.
From the aircraft performance engineer's viewpoint, the 777-300ER can operate 4000 NM with reserves and at 85% headwinds, at a take off weight of 630,000 lbs carrying full pax (358 in Emirates 3 class configuration) plus a thoughtful emergency supply of pallets loaded with 100 extra cases of beer for the Scottish football fans.
The ACN at that weight is 79, which is pretty close to the 74 PCN of the 06/24 runway, and using the 10% rule, the pavement engineer is almost certain to grant a concession. A final check is still needed by the aircraft performance engineer that it will hit nothing in the climb on a hot windless day with an engine out. JT can do that
Looks like it could be a viable operation to me. Except I'd prefer to fly A330s and make more money from it.
Cheers
Overrun
I think your answer lies somewhere in the holy trinity of airport engineering, aircraft performance engineering and airline economics.
I don’t often encounter runways which impose no limitations in terms of strength or length (excepting the Middle Eastern bedlam of Sheiks striving for the biggest and best). In the UK, most runways impose some compromise, and EDI is no exception. The essence of the answer on any runway upgrade is therefore to work out what traffic there will be (i.e. how many punters), and where they are going (route length), and that will dictate the aircraft takeoff weight and takeoff length.
I was a bit surprised when I checked the population of Edinburgh, and it showed as only 450,000. And 9 million pax/year. From the airline economist's viewpoint, that is at the bottom end of traffic needed for a decent sized airport, and I would think it might even be getting below that needed to have commercially viable B777-300ER operations on a daily basis. There is not much scope for bigger planes at smaller airports because it drops the frequencies down and the punters prefer higher frequencies. The medium sized 250 pax A330-200 is better fit at a place like Edinburgh than a 350 pax B777-300ER.
The issue of route length is a key one. The B777-300ER is a very long range plane – the map below shows its maximum range from EDI. That is pretty well non-stop anywhere in the civilised world (except Australia and New Zealand and we all know that the Antipodes is not part of the civilised world). I don’t think the traffic or market is there for those extreme range operations from EDI.
What is more likely to be viable is a medium range operation, 4000 NM. The next map shows that this gets to the Middle East (and thus by connection to anywhere else in the world), it gets direct to most of the USA and Canada, all of Europe, most of Africa, and some of Asia.
From the aircraft performance engineer's viewpoint, the 777-300ER can operate 4000 NM with reserves and at 85% headwinds, at a take off weight of 630,000 lbs carrying full pax (358 in Emirates 3 class configuration) plus a thoughtful emergency supply of pallets loaded with 100 extra cases of beer for the Scottish football fans.
The ACN at that weight is 79, which is pretty close to the 74 PCN of the 06/24 runway, and using the 10% rule, the pavement engineer is almost certain to grant a concession. A final check is still needed by the aircraft performance engineer that it will hit nothing in the climb on a hot windless day with an engine out. JT can do that
Looks like it could be a viable operation to me. Except I'd prefer to fly A330s and make more money from it.
Cheers
Overrun
Last edited by OverRun; 14th Nov 2010 at 13:09. Reason: Bad speling (sic; or should that be joke)
Overrun
Thank you for the very extensive and informative replies. At the risk of thread creep, where can PCNs for ramps and taxiways be found? As a GLEX operator, we are aware of restrictive PCNs and getting the data, but it is frequently ramps that have caused the grief of collapsing asphalt. One problem we have is that our runway performance can get us into airports that were not designed for nearly 100,000 pound airplanes.
GF
Thank you for the very extensive and informative replies. At the risk of thread creep, where can PCNs for ramps and taxiways be found? As a GLEX operator, we are aware of restrictive PCNs and getting the data, but it is frequently ramps that have caused the grief of collapsing asphalt. One problem we have is that our runway performance can get us into airports that were not designed for nearly 100,000 pound airplanes.
GF
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galaxy flyer
The PCNs for ramps and taxiways are not usually published by the airport, and there is no easy answer. I guess you have to ask each airport (and hope you get an answer - I often find that they don't know or won't tell).
Most airports will have strength data for each ramp and taxiway, and will taxi/park you where they think it is strong enough. Some do not have any technical data, and work off previous experience (which is little help if your plane is larger than normal). A very few are without care or attention.
If the airport is long established, the strength varies significantly between the different ramps and taxiways. Normally, the airport will deliberately map out a path of high strength taxiways and aprons to match the strength of the runway, so that a heavy plane can safely taxi in and park. When they overlay or strengthen the runway, they also work on this path of high strength taxiways and ramps.
But airports generally take a more relaxed view about overloading these because if you sink into a ramp, it can always be closed and repaired later. And if the thing ruts a lot, no-one is too worried because there are no high speed aquaplaning or roughness issues to worry about. The same cannot be said about the runway. My own place has high strength taxiways that are so badly rutted that they can't be fixed by asphalt overlay and will have to be rebuilt from the bottom up. But they still work, the surfacing is intact, and so we're not planning to rebuild anything just yet.
There are a couple of tricks for GLEX (and similar) pilots to use. When arriving at an airport for the first time, ask for high strength or airline parking (in case the airport doesn't realise that you are in the jet-airliner weight class). Then after you have parked and before you refuel, look at your tyres and the wheeltracks leading into the parking position and see if you have created progressively deeper ruts as you slowed down to a stop, or see if you are sinking in. If you have, drive or tug out of there before refuelling or loading.
If you have the luxury of checking out an airport before you operate there for the first time with a heavy aircraft, ask them to drive over slowly (also called proof roll) the suspect areas with the biggest fire truck or refuelling tanker. If it takes the weight of those, it should be OK for a 45 tonne aircraft. You can use a simple rule-of-thumb: each axle on a laden truck weighs 10 tonnes (or 20,000 lbs). So a small refuelling truck with 3 axles is probably 30 tonnes, and a fire truck is 20 tonnes. And if the pavement takes those without breaking, it should be OK for 1 pass of your 45 tonne (100,000 lb) aircraft.
Cheers
Overrun
Most airports will have strength data for each ramp and taxiway, and will taxi/park you where they think it is strong enough. Some do not have any technical data, and work off previous experience (which is little help if your plane is larger than normal). A very few are without care or attention.
If the airport is long established, the strength varies significantly between the different ramps and taxiways. Normally, the airport will deliberately map out a path of high strength taxiways and aprons to match the strength of the runway, so that a heavy plane can safely taxi in and park. When they overlay or strengthen the runway, they also work on this path of high strength taxiways and ramps.
But airports generally take a more relaxed view about overloading these because if you sink into a ramp, it can always be closed and repaired later. And if the thing ruts a lot, no-one is too worried because there are no high speed aquaplaning or roughness issues to worry about. The same cannot be said about the runway. My own place has high strength taxiways that are so badly rutted that they can't be fixed by asphalt overlay and will have to be rebuilt from the bottom up. But they still work, the surfacing is intact, and so we're not planning to rebuild anything just yet.
There are a couple of tricks for GLEX (and similar) pilots to use. When arriving at an airport for the first time, ask for high strength or airline parking (in case the airport doesn't realise that you are in the jet-airliner weight class). Then after you have parked and before you refuel, look at your tyres and the wheeltracks leading into the parking position and see if you have created progressively deeper ruts as you slowed down to a stop, or see if you are sinking in. If you have, drive or tug out of there before refuelling or loading.
If you have the luxury of checking out an airport before you operate there for the first time with a heavy aircraft, ask them to drive over slowly (also called proof roll) the suspect areas with the biggest fire truck or refuelling tanker. If it takes the weight of those, it should be OK for a 45 tonne aircraft. You can use a simple rule-of-thumb: each axle on a laden truck weighs 10 tonnes (or 20,000 lbs). So a small refuelling truck with 3 axles is probably 30 tonnes, and a fire truck is 20 tonnes. And if the pavement takes those without breaking, it should be OK for 1 pass of your 45 tonne (100,000 lb) aircraft.
Cheers
Overrun
OverRun
Thanks again for the answer and ideas. I don't have it but there a great photo of a Gulfstream with the left main gear deeply sunk into the ramp and the wingtip is about 6" from touching it.
Here it is: http://http://www.flightglobal.com/a...-business.html
GF
Thanks again for the answer and ideas. I don't have it but there a great photo of a Gulfstream with the left main gear deeply sunk into the ramp and the wingtip is about 6" from touching it.
Here it is: http://http://www.flightglobal.com/a...-business.html
GF
Last edited by galaxy flyer; 14th Nov 2010 at 04:00.