We receive our pattern altitude information from AOPA. Traffic Pattern Altitude (TPA) is listed in the A/FD. If the TPA is not published, then the pattern altitude is determined by our AOPA source utilizing local sources for the best information.
Image 1: TPA published in A/FD is displayed in the information section for this airport.
Image 2: AOPA sourced pattern altitude since no TPA is published in the A/FD.
The Aeronautical Charting Forum (an FAA/Industry public forum) has been dealing with the issue of determining traffic pattern altitudes on a more consistent basis than the way it is currently done. Part of their discussion has involved including all TPA information in the National Airspace Systems Resources (NASR) data for each airport. This is the FAA source for navigation and airport data. Part of the effort will involve removing all pattern altitude information for standard pattern altitudes and only including data when the TPA is non standard. This will coincide with an update to the AIM wording on the next update.
The AFD data (now called the Chart Supplement) is also being updated to use the value included in the NASR source data. You can read more about this topic in the minutes of the last ACF meeting on page 6, recommendation 13-01-262
There are links to the historical discussion and to the proposed new wording for the AIM.
In the mean time, ForeFlight uses the value published in the NASR data, and if a value is not published, then AOPA data is used, and finally if no data is published, the value is calculated to be airport elevation plus 1000 feet. When the AIM update is published, ForeFlight will follow its language and use the NASR data as the source.