PCN/ ACN Mikonos A320 Question

[eagle21]

Could anyone look at the following for me please. I have calculated that the ACN on an A320 (MTOW 77T A/C) exceeds the PCN at LGMK with weights above 66t and the 10% buffer above 74t. If this is the case where can I find information on any aproval by the Greek Aviation Authrorities for operations of this aircraft type at MTOW in Mykonos?

Thanks for your help.

[OverRun]

Umm - 63.2t is the limit I think for an A320 on PCN 34 and B subgrade. And the 10% buffer is not recognized internationally for PCN - that might be an old LCN concession.

JMK = 34/F/B/X/U
F = flexible = asphalt
B = subgrade strength
X = medium pressure tyres < 1500 kPa
U = Using aircraft experience: representing knowledge of the specific type and mass of aircraft satisfactorily being supported under regular use.

A320-100 77t
PCN = 42. Tyres= 1450 kPa. Quite a bit over the pavement weight limit and a formal pavement concession is needed. The overload is 42/34 = 24%. It appears that others are using A320s there. Tyre pressure within limit and no concession needed for tyres.

To get the concession, I suggest you read your local Sunday paper for articles about how business is done in Greece.

[eagle21]

I am not familiar with the pavement concesion term. Does anyone know if airlines operating there with A320s need a special permit?

[john_tullamarine]

The pilot/operator should view the pavement limitations as limitations in the same way as aircraft limitations.

If you want to exceed them, you need to request that the relevant authority permit such an exceedance via some published procedure (or alternative, as suggested by OverRun, if that be appropriate). The permission usually is referred to as a concession or, sometimes, a dispensation but, nonetheless, is permission to do something which otherwise would not be permitted. Such a permission may involve mitigating limitations or may not be granted.

[eagle21]

Thanks for the explanation. My question now is to pilots flying A320 or A321s to Mikonos, do you have any information about any special permits to exceed this limits? Does your airline provide you with any information on the subject?

[LYKA]

My airline has approval from the Greeks to operate at weights above the publish PCN, what Airline do you work for?

[boby4]

Definition : MAW= max allowance weight MRW=maximum ramp weight

MAW= ZFW+(MRW-ZFW)*(PCN-ACNzfw)/(ACNmrw-ACNzfw)

in Jeppesen you will find your A 320
example:
Airbus A320-200
MRW= 77400
ZFW= 41345 load on MLG 46.6 Tire pressur 209 (X — Medium, limited to 1.50MPa (218psi))
F/B = ACNmrw=42 ACNzfw= 20

MAW= 64t289
Jeppesen :
f. Occasional minor overloading operations are
acceptable for:
1. flexible pavements by aircraft with ACN not
exceeding 10 per cent above the PCN;
Where overload operations are conducted the
Appropriate Authority should be consulted.

PCN = 34 if you apply f . PCNoccasional/overloading=1,1*34=37,4
Maw=69t861
easy no !!!:ok:

[boby4]

Boeing Pavement Strength Overload Guidance
A number of airlines have requested Boeing guidance concerning aircraft operating at weights above the published pavement strength rating of a runway. In all cases, the airport authority is the final authority concerning what are permissible operating weights for their airport facilities. The following guidance basically conforms / complies with ICAO Doc 9157-AN/901, Part 3, Chapter 2, "Guidance on Overload Operations."
For normal operations, pavement limits can usually be exceeded by 5 to 10 % without any appreciable impact on pavement life. For low frequency operations, overloads on the order of 10 to 25 % are usually considered acceptable, however the pavement should be in good condition, otherwise near-term deterioration may be initiated by the overload. For emergency situations, a 50-100% overload allowance is generally accepted, subject to the discretion of the airport involved.
The above is written in a generic fashion, such that if a pavement is rated strictly by weight (such as "Dual Tandem 300,000 pounds" for example) the overload percentages can be applied directly to the rated weight (a 10 % overload equates to a 330,000 pound allowance in this case). If however a pavement is rated by a Pavement Classification Number (PCN) or a Load Classification Number (LCN), the overload percentages are applied to the PCN (or LCN) number, so the allowed weights will not directly reflect the percentages indicated, but will relate to the PCN's or LCN’s that are so-increased. For example, if an airport has a PCN of 32 FB, the 25 % overload allowable for low frequency operations would be 40 FB (1.25 x 32). The corresponding weights in this case for a 737-800 would be 123,000 pounds for routine operations, and 157,000 pounds for the low frequency level of operations. Note that for any overload operations, the pavement should be in good condition, otherwise adverse effects may rapidly become evident.
Additional questions concerning this issue can be directed to Boeing’s Airport Technology group as follows:
Boeing Airport Technology P.O. Box 3707, MC 67-KR Seattle, WA 98124 425-237-1004 [email protected]
9/11/2009 Airport Technology Boeing Commercial Airplanes

[OverRun]

I feel uncomfortable with the overload limits suggested by boby4 from the Boeing/ICAO documentation. The ICAO reference used by boby4 dates back to 1983, and in my opinion the overload guidance was written more in the context of DC-3/DC-4 design runways being overloaded by narrow body jets. It is way out of line for aircraft weighing several hundred tonnes, where a cavalier 100% overload can be hundreds of tonnes extra.

I also add my sense that the aviation authorities of some States are concerned about the loss of engineering skills in their own ranks and in the ranks of the local airport staff, and getting nervous about even small very small overloads.

The 1998 Boeing document D6-82203 PRECISE METHODS FOR ESTIMATING PAVEMENT CLASSIFICATION NUMBER gives a much better approach in my opinion, with less overload permitted, and it is in line with the thinking of many airports and pavement engineers today:

For flexible pavements, occasional traffic cycles by aircraft with an ACN not exceeding 10 percent above the reported PCN should not adversely affect the pavement.

• For rigid or composite pavements, occasional traffic cycles by aircraft with an ACN not exceeding 5 percent above the reported PCN should not adversely affect the pavement.

• The annual number of overload traffic cycles should not exceed approximately 5 percent of the total annual aircraft traffic cycles.

• Overloads should not normally be permitted on pavements exhibiting signs of distress or failure, during any periods of thaw following frost penetration, or when the strength of the pavement or its subgrade could be weakened by water.

• Where overload operations are conducted, the airport authority should review the relevant pavement condition on a regular basis and should also review the criteria for overload operations periodically, since excessive repetition of overloads can cause severe shortening of pavement life or require major rehabilitation of the pavement.


And then

Any overload should be treated in terms of ACN and equivalent critical aircraft operations per individual operation. Allowance for the overload should be negotiated with the airport authority, since pre-approval cannot be assumed.


Now this should not be taken to exclude greater overloads. In my own work, at one airport we overload to 24% for three flights per week, and overload to 16% for another 20 flights a week. I’ve calculated the loss of pavement life due to overloading to be equivalent to two years for that runway, and the airport has made its commercial judgement and allowed the operations. We have an increased regime of pavement technical and engineering inspections, an airport engineer permanently on standby, and we monitor the overloads and their effect carefully by visual, FWD, rut depth and roughness monitoring. We also have an emergency overload list for very large aircraft likely to use the airport as a diversion, and their permitted landing weight for an emergency 50% overload. There are some airports with similar regimes.

But there are many more airports without the technical support, and that is where the 5% / 10% limits come into play. With the airport’s prior approval of course.

There is an easy way of checking the ACN at various weights. ACN charts for many aircraft, including some obscure ones, are here (http://profemery.info/aviation.html#ACN%20CHARTS)