I’m on a flight from ord to den right now. T-Mobile disappeared as an available option, but I found a workaround: I went into my safari history and found that https://directaccess.viasat.com/landing?deviceId=xxxxxx-xxxxx-xxxxx-xxxx is the url you can use if it doesn’t show up. Replace the X’s with your actual device id you can see from the url bar on other viasat pages.

this method also allows you to use T-Mobile free WiFi on laptops and iPads