View Full Version : Aircraft classification numbers/ pavement classification numbers

12th May 2003, 02:39
Here’s one for any that use the Aerad supplements.

If an airport is showing a PCN 32/R/B/W/T can a B767-300 use this airport?
(Unrestricted use)
For a 767 rigid pavement, medium, has an ACN of 51 at 172819 kg and an ACN of 20 at 87926 kg. Can I interpolate to get an ACN of 32, which would be 120782 kg; this would be the max weight for unrestricted use.

Any comments appreciated.

galaxy flyer
12th May 2003, 08:27
The aircraft's ACN cannot exceed the PCN for the surface, but there's more to it. The PCN is, by definition the lowest strength section of the runway surface i.e. the touchdown area might be PCN 55 but the midfield might be PCN of 30 and the runway would advertised as having a PCN of 30.

Also, the PCN number is based on civil engineering requirements for a certain number of "passes" down the surface without damaging it. Typically for USAF CE, it is 10,000 passes. This means, for us, we can waiver a limited number of operations on the runway for aircraft exceeding the PCN. In other words, PCN usually has more to do with damage to the surface than airplanes sinking into oblivion.


8th Feb 2005, 10:27
Has the captain take into consiederation ACN/PCN relationship while determine MTOFW?

9th Feb 2005, 04:53

Interpolation between the ACN values is acceptable.


At the end of the day, the buck stops with the Captain, in the event of an accident (For ANY reason) he will be accused of operating the aircraft at a weight above a published limitation. Its therefore in his best interest not to do so!


Old Smokey
9th Feb 2005, 05:06

Yes, it must be taken into consideration unless you have a dispensation.

A MTOW calculation would typically include separate evaluation of WAT Limit, Field Length Limits, Obstacle Limits, Mbe limits, Structural Limits, and ACN Vs PCN Limits. The resultant MTOW is then the LEAST of the separate limits found above.

Old Smokey