PCN: Pavement Classification Number
Each part of the code is separated by a forward-slash.
- PCN numerical value: it indicates the load-carrying capacity of the pavement.
- First letter: it indicates the rigidity of the pavement
- R for rigid (most typically concrete)
- F for flexible (most typically asphalt)
- Second letter: it expresses the strength of what is underneath the pavement section, known as the subgrade
- A for high strength : characterized by K = 150 MN/m^3 and representing all K values above 120 MN/m^3 for rigid pavements, and by CBR = 15 and representing all CBR values above 13 for flexible pavements.
- B for medium strength: characterized by K = 80 MN/m^3 and representing a range in K of 60 to 120 MN/m^3 for rigid pavements, and by CBR = 10 and representing a range in CBR of 8 to 13 for flexible pavements.
- C for low strength: characterized by K = 40 MN/m^3 and representing a range in K of 25 to 60 MN/m^3 for rigid pavements, and by CBR = 6 and representing a range in CBR of 4 to 8 for flexible pavements.
- D for ultralow strength: characterized by K = 20 MN/m^3 and representing all K values below 25 MN/m^3 for rigid pavements, and by CBR = 3 and representing all CBR values below 4 for flexible pavements.
- Third letter: it expresses the maximum tire pressure that the pavement can support
- W: Unlimited: no pressure limit
- X: High: pressure limited to 1.75 MPa
- Y: Medium: pressure limited to 1.25 MPa
- Z: Low: pressure limited to 0.50 MPa
- Fourth letter: it describes how the PCN numerical value was determined
- T indicates technical evaluation
- U indicates usage – a physical testing regime
Example 1. If the bearing strength of a rigid pavement, resting on a medium strength subgrade, has been assessed by technical evaluation to be PCN 80 and there is no tire pressure limitation, then the reported information would be:
PCN 80 / R / B / W / T
Example 2. If the bearing strength of a composite pavement, behaving like a flexible pavement and resting on a high strength subgrade, has been assessed by using aircraft experience to be PCN 50 and the maximum tire pressure allowable is 1.25 MPa, then the reported information would be:
PCN 50 / F / A / Y / U
Example 3.— If the bearing strength of a flexible pavement, resting on a medium strength subgrade, has been assessed by technical evaluation to be PCN 40 and the maximum allowable tire pressure is 0.80 MPa, then the reported information would be:
PCN 40 / F / B / 0.80 MPa /T
PCN is normally published on charts.
ACN: Aircraft Classification Number
The airplane manufacturer provides the official computation of a reference ACN value. Nevertheless, the computation of the actual ACN requires detailed information on the operational characteristics of the airplane such as maximum centre of gravity, maximum ramp weight, wheel spacing, tire pressure, and other factors.
A typical ACN for a given aircraft is normally provided as follows:
The actual ACN of a given aircraft of weight M and corresponding to a pavement with known characteristics can be calculated as follows:
Mmin is the Operating Empty Weight
Mmax is the Maximum Apron Weight
M is the landing Weight
ACNmin and ACNmax are the ACN corresponding to Mmin and Mmax respectively.
Practice of ACN/PCN method
An aircraft, characterized by its actual operating weight (at pushback, taxi, takeoff and landing), is authorized to operate and manoeuvre on a given airport zone (ramp, apron, taxiway, runway) depending on the comparison between its actual ACN and the published PCN of the concerned pavement.
Tolerance of acceptation
Flowchart of the ACN/PCN method
- ICAO Documentation Annex 14 - Aerodromes - Volume I - Aerodrome Design and Operation - 8th Edition July 2018 - Chapter 2.6
- VID 150259 - Creation
- VID 435695 - Wiki integration
- VID 150259 - Update October2019
DATE OF SUBMISSION
- 05:48, 14 November 2019
- This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.
- The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.