Missing zipcodes (at US airports)

I'm building an application which makes use of GPS positioning to get a user's coordinates, and then Yahoo! Placefinder to get the zipcode at those coordinates (it does other things as well..)

During testing your service returned no zipcode (<uzip/>). The testing took place at Dulles Airport. Neither will it return zipcodes for La Guardia or JFK, which makes me think that this particular problem is related to airports (though I get a zipcode for LAX). As far as I understand large airports often their own zipcodes, but why are these zipcodes missing from your service?

Obviously the application, which targets users of mobile devices, needs to work also at airports.

I hope you can look into this issue. Thanks.

Lars

Would you provide an example request that is not producing the desired result? All of the mentioned airports have zipcodes associated with them. One issue you may be encountering is that airports sometimes have unnamed roads that are not associated with a zipcode. If your point is closest to one of these roads, you will not get a zipcode back.

Eddie Babcock
Yahoo! Geo Technologies

Certainly (and I can only apologize for forgetting to include it previously):

38.946691 -77.448549 (Dulles)
40.643538 -73.782066 (JFK)
40.773197 -73.872457 (La Guardia)

As to your comment about roads; I think there has been an assumption, on my part, that every land coordinate pair in the US would have a zipcode associated with it. Clearly that's not always the case. Are there other such exceptions that you are aware of in addition to airport roads?

Thanks a lot for your assistance!

Lars