Please don't. Data on the connections that a flight uses is not cheap and speed is slow. Other passengers would have a worse experience if someone exploits data usage.
I wasn't thinking about the narrow bandwidth available and actual costs. You are right, i am changing my mind since it doesn't seem ethical.
You'll probably run out of it's in the DHCP scope anyway.
Honestly, long plane rides are my time to read books and watch movies. OK, there are sometimes specific circumstances where you need to work on the Internet while flying to a big meeting or whatever. But I avoid it whenever possible. I don't actually need to be online all the time.