[Crumpp]

claimed the elevation changes

NO, I said the current settings do not agree with the elevation and not all charts are the same.

Why don't you call Jepperson and ask how many elevation changes they make a year on plates and charts.

Here is the Advisory Circular for it.

This advisory circular (AC) provides general guidance and information for airport authorities in the collection and management of data describing the physical infrastructure, characteristics, and services of their airport.

If you are requesting to establish or change the Airport Elevation for your airport

2.5.2 How do you collect the data?
Depending on the level of airport (see paragraph 1.1) the collection of safety critical data requires specialized tools and training. For Level II airports we allow the use of hand held GPS receivers meeting certain standards and following defined processes outlined in this AC. Data collection at a Level III airport requires professional engineering and surveying services to collect and format the data (See AC 150/5100-14, Architectural, Engineering, and Planning Consultant Services for Airport Grant Projects).

2.5.2.2 Data collection at level I airports
For Level I airports, use the tools and processes Airports GIS provides to capture the location and the necessary attribution describing the characteristics of the feature. The design of the application walks you through the steps to complete the data capture. Review the User’s Guide and complete the on-line training before you use the system to capture data.

2.5.3 Data accuracy
The accuracy of features at Level I airports is a function of the positional accuracy of the base data set (imagery or map) and associated processes of Airports GIS. Accuracy information using this method will always be an estimated value. Accuracy of features at Level II airports is a function of the post processing of the data to achieve a horizontal position accuracy of 5 feet relative to the North American Datum of 1983 (NAD 83). Data providers must use latitude and longitude as the unit of measurement. The vertical position (elevation) requirement is 10 feet relative to the North American Vertical Datum of 1988 (NAVD 8 with a unit of measurement of feet. AC 150/5300-18 contains the accuracy requirements for Level III airport data.

http://www.faa.gov/documentLibrary/m...50_5300_19.pdf

When you make a map, there is large room for error both horizontally and vertically. That is why there is so many different datums and it is extremely important you are on the same datum as others in the system.

That is why aerial navigation is by convention.

In fact, Verticle Datum has been one of the most problematic areas in navigation until recent technological advances. Those advances is what allowed us to put JDAM's into multiple cave entrances on the side of a mountain in 2003.

http://www.usna.edu/Users/oceano/pgu...L%20DATUMS.htm