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!
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? The empty weight of a 773ER (370,000lbs) is just under half the MTOW (775,000lbs) and the data I found stated that the ACN at MTOW on a 74R/C/W/T pavement is 107 so I'd have thought the ACN for an empty 773ER would be about 51 (i.e. 370/775*107). If I divide the MTOW by the ACN for that weight (107) and then multiply by the PCN for the aprons (72R/C/W/T, which is slightly less than the PCN of 06/24) I get a maximum take off mass at EDI of 521,500lbs. According to the Boeing payload/range charts, this is about enough for a full load of passengers and fuel to reach Paris but not much further. If I’m right then long-range operations from EDI with a 773ER would be out of the question until the PCNs are significantly upgraded and it would explain why Emirates chose GLA over EDI.
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.