Not sure where AirportData gets its data but there are some inconsistencies: For example: airport KLLR has FAA designation LLR not FL10 airport CN66 is missing from the data set.

Makes me think the data is not refreshed very often. FAA data is usually updated/changed every 14-28 days. Airnav has up to date data but no API.

Interesting factoid: Mathematica can model magnetic anomaly to high degree of accuracy. But FAA attaches and updates a magnetic correction to VOR navaid data "occasionally." So you have to "look it up" and it may NIOT agree with actual magnetic anomaly at that Lat/Lon. O well.