I can't agree with "perfectly fine" here. Not unless you enabled local echo in your terminal emulator. The keyboard latency, especially for typo correction, was maddening. I still remember what a staggering QoL improvement it was the first time I used a low-latency connection to a server.

I would hazard a guess that the main problem with in-flight wifi is that it is going to DPI'd beyond recognition.

So you're never going to know what is "real" packet loss and what is the DPI saying "computer says no".

The Sandvine/Procera[1] system that many (most ?) airlines use is an ML-based DPI that looks at absolutely everything in an effort to correlate obfuscated traffic to the actual flow. IIRC they claim 98% accuracy.

[1] https://www.sandvine.com/