Offset limited to 390?

I was playing around with the Search JSON endpoint trying to figure out how many objects get returned for certain filters, but no matter what the filter, I got a maximum offset of 390. Am I doing something wrong, or is there some sort of limit being placed on the API side?

My end goal is to figure out, on average, how many commercial flights are in US airspace at a given time in order to estimate project cost, so if anyone could help with that additionally, I would much appreciate it!

Enumerating through very large results is not an ideal use-case for FlightXML, which is best suited for narrow queries of specific flights. Can you describe a little more what your application intends to actually do?

Depending on your scenario, it might be more reasonable to look into our “Firehose” API instead, which lets you stream all flight activity events as they happen.