I spent a recent flight finding out what I could do with a connection to the flight’s wifi, but without access to the internet.

I was on my way home from Strange Loop, a direct flight from St. Louis to Oakland.
It’s a long enough flight that I planned to purchase the $8 internet access and get some work done, but Southwest’s wifi portal wouldn’t accept any form of payment.
The web page didn’t give me any helpful error messages, so I opened up my browser’s network dev tools to see if I could figure out what was going wrong.

I found the failing request, but it didn’t provide any useful hints to point me toward a solution.
While I was there, I saw another request that caught my eye: A repeating successful request for current.json.

Here’s an example response from one of those requests:

{
  "sat_commlink_portal": {
    "status": "conn_ok",
    "time": "Sun Sep 24 22:02:19 2023"
  },
  "pcent_flt_complete": 33,
  "altVal": "35998",
  "lon": "-100.755",
  "satcomm_status": {
    "commlink": "active",
    "linkparams": "not-stale"
  },
  "dtzone": "PDT",
  "within_us": true,
  "etad": "06:19 PM",
  "lat": "40.201",
  "gspdVal": "487",
  "ttgc": "2h 25m",
  "dist_remain": "1167",
  "actime24": "15:54"
}

This appeared to be the data that drives the in-flight wifi portal’s flight status page.
Since this was one of the only things I could access on this network, I decided to make the most of it.

I used my browser’s “Copy as cURL” feature to quickly get a command to hit the endpoint.
As an aside, this feature is present in Firefox and all chromium-based browsers and it’s really handy if you ever need to reply requests made by your browser and want to send all the same headers.

After some experimenting, I found that none of the cookies or headers that were included in the request were strictly necessary, meaning that I could fetch the data with a simple curl 'https://getconnected.southwestwifi.com/current.json'.
I set up a loop to dump the data in a log file:

watch -n 30 "curl https://getconnected.southwestwifi.com/current.json | jq -c >> flight-logs"

I didn’t know what I’d do with the data at this point, but I started collecting it right away so that I’d have as much as possible to play with later.

With that running, I decided to look more closely at the responses to figure out what exactly I had to work with.
Here’s that same example response, annotated with my best guess at what the fields represent:

{
  // This looks like info about the system's satellite internet connection.
  "sat_commlink_portal": {
    // The connection is okay!
    "status": "conn_ok",
    // I'm not sure what this time is.
    // It hasn't changed at all.
    "time": "Sun Sep 24 22:02:19 2023"
  },

  // The percentage progress of the current flight.
  // I don't kn