Genuine question here - isn't Tor traffic reputed for having a certain "footprint"?
I would be worried about accessing the Tor network over public WiFi, but maybe that's just me.
But when you start using pluggable transports, like Obfs4, you can defeat pretty much every captive portal or traffic analyzer. I'm sure there might be a way to detect even these. But remember that the real test of detection is the GFoC.
Some piddly airline's offering of pay internet is not going to use nation-state level detection schemes.
