Engineering:ACN-PCN method

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Short description: Airport pavement rating system

The Aircraft Classification Number (ACN) – Pavement Classification Number (PCN) method is a standardized international airport pavement rating system promulgated by the ICAO in 1981. The method has been the official ICAO pavement rating system for pavements intended for aircraft of apron (ramp) mass greater than 5700 kg from 1981 to 2020.[1] The method is scheduled to be replaced by the ACR-PCR method by November 28, 2024.[2]

For the safe and efficient use of pavements, the method has been designed to:

  1. enable aircraft operators to determine the permissible operating weights for their aircraft;
  2. assist aircraft manufacturers to ensure compatibility between airfield pavements and the aircraft under development;
  3. permit airport authorities to report on the aircraft they can accept and allow them to use any evaluation procedure of their choice to ascertain the loading the pavements can accept.[3]

The method relies on the plain comparison of two numbers:

  • The ACN, a number that expresses the relative effect on an airplane of a given weight on a pavement structure for a specified standard subgrade strength;
  • The PCN, a number (and series of letters) representing the pavement bearing strength (on the same scale as ACN) of a given pavement section (runway, taxiway, apron) for unrestricted operations.

Aircraft Classification Number (ACN)

The ACN calculation process is fully described in ICAO Doc 9157 Aerodrome Design Manual – Part 3 "Pavements" (2nd ed.).[4]

The procedure to calculate the ACN is as such:

  1. Design a theoretical pavement according to a defined criterion:
    • For flexible pavements, design the pavement for 10,000 load applications of the aircraft according to the CBR design procedure combined with Boussinesq's solution for deflection in the elastic half-space
    • For rigid pavements, design the pavement to reach a standard flexural stress of 2.75 MPa at the bottom of the cement concrete layer according to Westergaard theory
  2. Calculate the single wheel load, inflated at 1.25 MPa, that would require the same pavement – this is the Derived Single Wheel Load (DSWL)
  3. The ACN is defined as twice the DSWL, expressed in thousands of kilograms
Procedure for the calculation of ACN

The ACN are calculated for four standard subgrade strengths, for flexible and rigid pavements, thus leading to 8 different values.

ACNs depend on the landing gear geometry (number of wheels and wheel spacing), the landing gear load (that is dependent upon the aircraft weight and center of gravity) and the tire pressure.

Normally, the aftmost center of gravity for the Maximum Ramp Weight (MRW) lead to the critical ACN.

Aircraft manufacturers publish the ACNs of their aircraft in their respective Aircraft Characteristics manuals.

The ICAO Aerodrome Design Manual contains the source code of computer programs for the calculation of ACNs. The FAA also developed COMFAA, a software enabling the calculation of ACNs for different aircraft depending on the input parameters.[5]  

Pavement Classification Number (PCN)

Contrary to the ACN, the ICAO does not prescribe a standardized calculation procedure for the PCN.[4] Different PCN calculation procedures may therefore be found around the world.

However, the ICAO defines a standardized reporting format for the PCN that comprises the PCN numerical value and a series of 4 letters.[1]

PCN may also be known as Load Classification Number or LCN.

Pavement Classification Number - Code letters definitions
Pavement type
Rigid pavement R
Flexible pavement F
Subgrade strength category
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. A
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 B
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 C
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 D
Maximum allowable tire pressure
Unlimited: no pressure limit W
High: limited to 1.75 MPa X
Medium: limited to 1.25 MPa Y
Low: limited to 0.50 MPa Z
Evaluation method
Technical evaluation T
Using aircraft experience U

PCNs depend on both the pavement structure and the aircraft traffic operated on the pavement.

The PCNs are determined by airports for their runways, taxiways and aprons and published in the Aeronautical Information Publication (AIP).  

Application by aerodrome authorities and aircraft operators

An aircraft having an ACN (at a given weight) equal to or less than the PCN can operate without restriction on the pavement, provided that its tire pressure does not exceed the PCN limitation.

If the ACN exceeds the PCN, some restrictions (for example on weight of frequency of operation) may apply depending on the national or local regulations for overload operations.

With the exception of massive overloading, pavements in their structural behaviour are not subject to particular limiting load above which they suddenly or catastrophically fail.

As a result, minor or medium overload operations may be allowed by the airport authority depending on the corresponding loss in pavement life expectancy.

Evolutions and limitations

The ACN-PCN method underwent 2 major changes since its introduction in 1981:

  • In 2007, the ICAO adopted a new set of alpha-factors for the calculation of ACNs on flexible pavements based on findings from full-scale pavement tests. This led to a reduction of the flexible ACNs for all landing gears with four wheels or more.[6]
  • In 2013, the ICAO adopted new limits for the tire pressure categories, again based on findings from full-scale pavement tests.[7][8]

Despite these changes, the ACN-PCN method gradually became inconsistent with recent pavement design methods, mostly based on Linear Elastic Analysis (LEA) or Finite Element Method (FEM). The method is also failing to consider accurately the effect of modern landing gear configurations (with multi-wheels arrangements) and the improved characteristics of new-generation pavement materials.

As a result, the ICAO triggered the development of a new pavement rating method aimed at overcoming these deficiencies.[9] This new system, the ACR-PCR method, became effective in July 2020.

Aircraft ACN list

Aircraft Classification Numbers (ACNs)
Aircraft Weight
Maximum
(kN) 		Tire
Pressure
(MPa) 		Flexible pavement sub-grades
CBR% 		Rigid pavement sub-grades
k (MPa/m3)
High Medium Low Very low High Medium Low Ultra low
A B C D A B C D
Airbus A330-200 (Configuration 1) 2,137 1.34 57 62 72 98 48 56 66 78
Airbus A330-200 (Configuration 2) 2,264 1.42 62 67 78 106 53 61 73 85
Airbus A330-300 (Configuration 1) 2,088 1.31 55 60 70 94 46 54 64 75
Airbus A330-300 (Configuration 2) 2,137 1.33 57 61 71 96 47 55 65 77
Airbus A330-300 (Configuration 3) 2,264 1.42 62 68 79 107 54 62 74 86
Airbus A380-800 (6 Wheel Main Gear) 5,514 1.47 56 62 75 106 55 67 88 110
Airbus A380-800 (4 Wheel Wing Gear) 5,514 1.47 62 68 80 108 55 64 76 88
Boeing 737-800 777 1.47 44 46 51 56 51 53 55 57
Boeing 737-900 777 1.47 44 46 51 56 51 53 55 57
Boeing 737-BBJ 763 1.47 43 45 50 55 50 52 54 56
Boeing 747-400, 400F, 400M 3,905 1.38 53 59 73 94 53 62 74 85
Boeing 747-400D (Domestic) 2,729 1.04 36 39 47 65 30 36 43 51
Boeing 747-400ER 4,061 1.58 57 63 78 100 59 69 81 92
Boeing 747SP 3,127 1.26 45 50 61 81 40 48 58 67
Boeing 777-300 2,945 1.48 53 59 72 100 54 68 88 108
Boeing 777-300ER 3,345 1.52 64 71 89 120 66 85 109 131
Boeing 787-9 2,240 1.57 60 66 81 106 61 71 84 96
BAC-111 Series 400 390 0.97 23 24 27 29 25 27 28 29
BAC-111 Series 475 440 0.57 23 28 29 32 26 28 29 31
BAC-111 Series 500 467 1.1 29 31 33 35 33 34 35 36
BAe-146-100 376 0.84 18 20 23 26 20 22 24 25
BAe-146-200 416 0.97 22 23 26 29 24 26 27 29
BAe-146-300 436 1.1 24 25 28 31 27 28 30 31
BAe ATP 232 0.85 12 13 14 16 13 14 15 16
Beech 1900C, 1900D 76 0.67 3 4 4 5 4 4 5 5
Beech Starship 2000 65 0.54 2 3 4 4 3 4 4 4
Beech Jet 400, 400A 73 0.86 6 7 7 7 6 6 6 6
Beech King Air 100, 200 Series 56 0.73 2 3 3 4 3 3 3 4
Beech King Air 300, 300C, 350, 350C 67 0.73 3 3 4 4 4 4 4 4
Bombardier 415 (Canadair CL-215, 415) 196 0.53 12 14 17 17 14 14 15 15
Bombardier BD-700, Global Express, XRS 437 1.15 26 28 31 32 30 31 32 33
Bombardier Challenger 300 168 1.21 9 9 11 12 11 11 12 12
Bombardier Challenger 800 237 1.12 13 14 16 17 16 16 17 18
Bombardier Challenger CL 600, 601, 604 215 1.21 12 13 15 16 15 15 16 16
Bombardier CRJ100, CRJ200, CRJ440 237 1.12 13 14 16 17 16 16 17 18
Bombardier CRJ700 Series 335 1.06 18 18 21 24 20 21 22 23
Bombardier CRJ900 Series 377 1.06 21 21 24 27 23 24 26 27
Bombardier Dash 8 Q100, Q200 Series 162 0.9 8 8 9 11 9 9 10 10
Bombardier Dash 8 Q300 Series 192 0.67 8 9 11 13 10 11 11 12
Bombardier Dash 8 Q400 287 0.67 14 16 18 20 16 17 18 19
Bombardier Global 391 1.15 23 24 27 29 26 27 28 29
C-123K Provider (Fairchild/Republic) 267 0.69 20 22 24 25 21 21 22 22
C-141B Starlifter (Lockheed) 1,553 1.31 52 60 73 88 51 61 70 78
C-17A (Globemaster III) 2,736 0.95 46 51 61 80 55 51 61 76
C-5 Galaxy (Lockheed) 3,723 0.77 31 33 40 51 28 31 37 45
Cessna 501 (Citation I – Eagle) 56 0.69 4 5 5 5 4 5 5 5
Cessna 550 (Citation II) 64 0.69 5 5 6 6 5 5 5 5
Cessna 550 (Citation Bravo) 67 0.69 5 6 6 6 5 5 6 6
Cessna 560 (Citation V, Ultra, Encore) 75 0.69 6 6 7 7 6 6 6 6
Cessna 560 XL (Citation Excel) 90 1.48 9 9 9 9 9 9 9 9
Cessna 650 (Citation III, VI) 99 1.02 6 6 7 7 7 7 7 7
Cessna 650 (Citation VII) 104 1.16 6 7 7 8 7 8 8 8
Cessna 750 (Citation X) 160 1.16 10 11 12 12 12 12 13 13
Convair 240 190 0.64 7 9 10 12 9 10 10 11
Convair 340, 440, 540 222 0.47 7 9 11 14 9 10 11 12
Convair 580 259 0.59 10 12 14 17 12 13 14 15
Convair 5800 280 0.59 11 13 15 19 13 14 16 17
Convair 600 210 0.73 9 10 11 14 10 11 12 13
Convair 640 245 0.52 8 11 12 15 10 12 13 14
Convair 880 860 1.03 27 31 36 44 26 31 36 40
Convair 990 1,135 1.28 40 46 53 64 40 47 54 60
Dassault Falcon 164 1.36 9 10 11 12 11 12 12 13
Dassault Falcon 2000EX 189 1.51 11 12 13 14 14 14 15 15
Dassault Falcon 10 84 0.93 5 5 6 6 6 6 6 6
Dassault Falcon 20 128 0.92 8 9 9 10 10 10 10 10
Dassault Falcon 50 173 0.93 9 10 12 13 11 12 12 13
Dassault Falcon 900 202 1.3 11 12 14 15 14 14 15 15
Douglas DC-3 147 0.31 5 7 10 12 8 8 9 9
Douglas DC-4 335 0.53 12 15 17 21 14 16 17 19
Douglas DC-6, 6B 480 0.73 20 23 25 30 22 24 26 27
Douglas DC-7 (All Models) 640 0.89 34 36 42 46 37 40 42 44
Douglas DC-8-10, 20 Series 1,226 1.01 36 41 49 62 32 39 46 53
Douglas DC-8-43, 55, 61, 71 1,470 1.3 47 54 64 79 45 54 63 71
Douglas DC-8-61F, 63F 1,557 1.32 51 59 69 85 50 59 68 76
Douglas DC-8-62, 62F, 63, 72, 73 1,593 1.35 52 59 70 87 50 59 69 77
DHC-4 Caribou 130 0.28 2 3 5 7 4 4 5 6
DHC-5 Buffalo 187 0.41 6 8 10 12 8 9 10 11
DHC-6 Twin Otter Series 300 56 0.26 2 2 3 5 3 3 3 4
DHC-7 Dash 7 209 0.74 10 12 13 15 12 13 14 14
DHS-2 Conair Firecat 116 0.62 8 10 10 11 9 9 9 10
Dornier 228 Series 63 0.9 5 6 6 6 6 6 6 6
Dornier 328 Jet 155 1.13 8 8 10 11 10 10 10 11
Dornier 328-110 (Turboprop) 138 0.8 7 7 8 10 8 8 9 9
Dornier SA227 (Metro, Merlin, Expediter) 74 0.73 3 4 4 5 4 5 5 5
Douglas A-26 Invader 120 0.48 7 8 10 11 8 8 9 9
Douglas B-26 Invader 156 0.48 9 11 13 14 10 11 11 12
Embraer 170, 175 368 1.04 20 21 24 26 22 24 25 26
Embraer E-190 481 1.1 28 30 33 35 31 33 35 36
Embraer E-195 52.29 1.04 25.3 26.3 29.2 34.1 27.4 29.4 31.4 33
Embraer EMB-110 (Bandeirante) 59 0.62 4 5 5 5 5 5 5 5
Embraer EMB-120 (Brasilia) Series 119 0.76 5 6 7 8 7 7 7 8
Embraer ERJ-145 Series 237 0.9 14 15 16 17 16 16 17 18
Fokker 100 452 0.94 25 27 31 33 28 30 31 33
Fokker 50 205 0.59 9 11 13 14 11 12 13 13
Fokker 60 226 0.62 10 13 14 16 13 14 14 15
Fokker 70 410 0.81 21 24 27 30 24 26 27 29
Fokker F27 Friendship 205 0.57 9 11 13 14 11 12 13 13
Fokker F28 Fellowship 325 0.53 14 17 20 23 16 18 20 21
Gulfstream G100 (IAI-1125-Astra SPX) 111 0.86 6 6 7 8 7 7 7 8
Gulfstream G159 156 0.83 8 8 10 11 9 10 10 11
Gulfstream G200 (IAI-1126-Galaxy) 159 0.86 9 10 11 12 10 11 11 12
Gulfstream II 294 1.04 17 18 20 22 20 21 21 22
Gulfstream III 312 1.21 19 20 22 23 22 23 23 24
Gulfstream IV 334 1.21 20 22 24 25 24 25 25 26
Gulfstream V 405 1.37 26 28 30 31 31 32 32 33
Hawker 1000 (BAe 1000A) 138 0.83 8 8 9 10 9 9 10 10
Hawker 400XP (Beech Jet 400A) 73 0.86 6 7 7 7 6 6 6 6
Hawker 800, 800XP (HS-125-800, 800XP) 125 0.83 7 7 8 9 8 8 9 9
Hercules C-130, 082, 182, 282, 382 778 0.67 29 34 37 43 33 36 39 42
Hercules L-100 (Commercial) 693 0.74 27 30 33 38 30 33 35 38
HS/BAe 125 (All Series to 600) 112 0.83 6 6 7 8 7 7 8 8
HS/BAe 700 114 0.88 6 7 7 8 7 8 8 8
HS/BAe 748 227 0.51 9 11 14 16 11 12 13 14
Ilyushin Il-18 625 0.8 16 17 21 29 13 16 20 23
Ilyushin Il-62, 62M 1,648 1.65 52 58 68 83 51 59 68 77
Ilyushin Il-76T 1,677 0.64 24 27 34 45 29 33 30 34
Ilyushin Il-76TD 1,775 0.66 27 30 37 49 32 35 32 37
Ilyushin Il-86 2,054 0.88 34 36 43 61 26 31 38 46
Jetstream 31, 32 (BAe) 69 0.39 3 4 5 6 4 5 5 5
Jetstream 41 (BAe) 107 0.83 5 5 6 7 6 6 7 7
KC-10 (McDonnell Douglas) 2,593 1.22 59 65 79 107 50 59 72 84
KC-135 Stratotanker (Boeing) 1,342 1.38 38 41 49 64 35 40 48 55
Lockheed L-1011-1 Tristar 1,913 1.35 52 56 66 90 45 52 62 72
Lockheed L-1011-100, 200 Tristar 2,073 1.35 57 63 75 101 49 58 69 81
Lockheed L-1011-250 Tristar 2,269 1.35 64 71 86 114 55 66 79 91
Lockheed L-1011-500 Tristar 2,295 1.35 65 72 87 116 56 67 80 93
Learjet 24F (Bombardier) 62 0.79 3 3 4 4 4 4 4 4
Learjet 25D, 25F (Bombardier) 69 0.79 3 4 4 5 4 5 5 5
Learjet 25G (Bombardier) 75 0.79 4 4 5 5 5 5 5 5
Learjet 28, 29 (Long-horn) (Bombardier) 69 0.79 3 4 4 5 4 5 5 5
Learjet 31A, 35A, 36A (Bombardier) 83 0.79 4 5 5 6 5 5 6 6
Learjet 40, 45, 45XR (Bombardier) 98 0.79 5 6 7 7 6 7 7 7
Learjet 55B, 55C (Bombardier) 97 1.24 6 6 7 7 7 7 7 7
Learjet 60 (Bombardier) 106 1.48 6 7 7 8 8 8 8 8
Lockheed 188 Electra 503 0.95 27 29 33 36 30 32 34 36
McDonnell Douglas CF-18 Hornet 249 1.38 21 20 20 20 21 21 21 21
McDonnell Douglas DC-9-10, 15 404 0.93 22 23 26 29 24 26 27 28
McDonnell Douglas DC-9-21 445 1.02 25 26 30 32 28 29 31 32
McDonnell Douglas DC-9-30, 32 485 1.05 27 29 33 35 30 32 34 35
McDonnell Douglas DC-9-41, 50, 51 543 1.17 31 33 37 40 35 37 39 40
McDonnell Douglas DC-10-10, 10CF, 15 2,037 1.34 57 62 74 101 49 58 69 80
McDonnell Douglas DC-10-20, 20CF, 30CF, 40CF 2,485 1.14 60 67 81 110 49 59 72 85
McDonnell Douglas DC-10-30, 30ER, 40 2,593 1.22 59 65 79 107 50 59 72 84
McDonnell Douglas MD-11 2,805 1.38 67 74 90 119 58 69 83 96
McDonnell Douglas MD-81 628 1.14 36 38 43 46 41 43 45 46
McDonnell Douglas MD-82 670 1.14 39 41 46 49 43 46 48 50
McDonnell Douglas MD-83 716 1.14 42 45 50 53 47 50 52 54
McDonnell Douglas MD-87 628 1.14 36 38 43 46 41 43 45 46
McDonnell Douglas MD-88 670 1.14 39 41 46 50 44 46 48 50
McDonnell Douglas MD-90-30 699 1.14 41 43 48 52 46 48 50 52
McDonnell Douglas MD-90-30ER 739 1.14 44 47 52 55 49 51 54 56
McDonnell Douglas MD-90-50, 55 772 1.14 46 50 54 57 52 54 57 58
P-3A/B/C Orion 623 1.31 38 41 44 47 44 46 48 49
Saab 2000 226 0.69 11 13 14 16 13 14 15 15
Saab 340 A, B 131 0.82 6 7 8 9 7 8 8 9
Sepecat Jaguar (Configuration 1) 154 0.58 7 9 10 11 9 10 10 11
Sepecat Jaguar (Configuration 2) 108 0.58 4 6 6 7 6 6 7 7
Shorts 330 102 0.55 6 8 9 9 7 8 8 8
Shorts 360 121 0.54 7 9 10 11 9 9 9 9
Shorts Sherpa 114 0.54 7 8 10 10 8 8 9 9
Shorts Skyvan 67 0.28 2 3 4 6 4 4 4 4
Sukhoi Superjet 100 46 1.11 24.8 24.8 28 31.5 27 28.6 30.1 31.3
Swearingen SJ30-2 60 1.07 3 3 3 4 4 4 4 4
Transall C-160 500 0.38 8 10 13 18 10 10 10 13
Tupolev Tu-134 463 0.59 10 12 15 20 9 11 14 16
Tupolev Tu-154 961 0.93 19 22 28 37 18 24 30 36
Tupolev Tu-204, 214, 224, 234 1,096 1.38 31 33 40 53 29 34 40 46
Vickers VC10 Series 1,590 1.01 48 54 66 83 41 50 60 69

References

  1. ↑ 1.0 1.1 ICAO. (2018). AERODROMES : aerodromes design and operations.. [Place of publication not identified]: ICAO. ISBN 978-92-9258-483-2. OCLC 1136297937. https://www.worldcat.org/oclc/1136297937. 
  2. ↑ "New Aircraft Classification Rating (ACR) - Pavement Classification Rating (ACR) Method". First North American, Central American and Caribbean Working Group (NACC/WG) Aerodromes and Ground Aids (AGA) Implementation Task Force Meeting. Mexico City, Mexico: ICAO. July 3-7, 2023. https://www.icao.int/NACC/Documents/Meetings/2023/AGATF01/WGAGATF1-IP04.pdf. 
  3. ↑ Ministry of Defence, Defence Estates (2011). Design & Maintenange Guide 27: A Guide to Airfield Pavement Design and Evaluation. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/552405/DMG_27.pdf. 
  4. ↑ 4.0 4.1 International Civil Aviation Organization. (1983). Aerodrome design manual pavements (2nd ed.). Montreal, Canada: International Civil Aviation Organization. ISBN 92-9194-117-4. OCLC 456683744. https://www.worldcat.org/oclc/456683744. 
  5. ↑ FAA Airport Technology (2014). "COMFAA 3.0". https://www.airporttech.tc.faa.gov/Products/Airport-Safety-Papers-Publications/Airport-Safety-Detail/ArtMID/3682/ArticleID/10/COMFAA-30. 
  6. ↑ International Civil Aviation Organisation (ICAO) (2007). AN 4/20.1-EB/07/26: Revised alpha factor values for the computation of Aircraft Classification Number (ACN) on flexible pavements. http://www.pavers.nl/pdf/Alpha%20Factor%20Values%20(ACN).pdf. 
  7. ↑ Airbus (2010). High Tire Pressure Test (HTPT). https://www.airbus.com/content/dam/corporate-topics/publications/backgrounders/techdata/pavement-publications/Airbus-Commercial-Aircraft-HTPT-final-report-31-Aug-2010.pdf. 
  8. ↑ Boeing (2009). "Boeing and Airbus Tire Pressure Test Programs". https://alacpa.org/index_archivos/ALACPA%202009%20Tire%20pressure.pdf. 
  9. ↑ Fabre, C. (2018). "The Aircraft Classification Rating – Pavement Classification Rating ACR-PCR". https://alacpa.org/ACR-PCR%20ALACPA-2018%20Cyril%20Fabre.pdf. 



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