Not your normal kind of piracy, I know, but thought some would be interested.
On a recent flight I was screwing around on my phone while connected to Southwest's WiFi. Southwest doesn't have traditional In-flight entertainment, instead offering movies and shows through a local LAN server on their WiFi for free. To get Internet access you load the site and pay $8usd using a CC, and then they'll unblock your device from the WAN.
Here's the fun part, for the LOLs I tried accessing my various VPNs and Proxies, including Google's, not expecting much. I've known of various tricks involving setting up a VPN or SSH on a DNS port or similar to try and get past web filters, but I've never been bothered enough to go through the trouble. But thinking of that, I decided to give Cloudflare's 1.1.1.1 DNS app a try, since while its kinda a VPN, it does some things differently since their goal isn't to give you a full VPN on their free plan, just improve your DNS and routing performance. But after waiting a long few seconds it amazingly said connected. At first I thought it was a fluke, thinking its connected but not actually working, but after doing a random Google search I realized it was actually somehow forwarding my packets to the WAN proper. I was FREE!
Though I should dampen expectations a bit. While it's definitely full net access, it's slower than molasses. Whatever route Cf is maneuvering packets through, it's not a fast one. Random access would be at best in the three digit Kbps range, with sustained sometimes spiking into the 1-2Mbps, and latency was measured in Seconds, not Milliseconds. Netflix refused to load the detail pages for movies and shows, and YouTube failed to load videos whether streamed or trying to download. I was able to get a 240p YT video to download with Youtube-DL/yt-dlp though.
And just to make sure it wasn't just the plane's connection that was slow, I checked with a seatmate that had paid the $8 for Internet access, and their experience was definitely faster than mine, loading videos with ease.
So while you can browse the net, read some articles, and chat on Mastodon and Lemmy, patience is a virtue. But it's way better than nothing, and great way to just check a few things in the air without dropping the $8.
YMMV with other airlines, but it's worth a shot.
Update: Just did another flight and this time didn't have success. The in-flight Wifi system on this flight was older though, with the old 2D flight tracker, and all the VOD content was broken too, so the Internet was probably just busted.