Delta, JetBlue, American Airlines and Alaska Airlines have free Internet as long as you are enrolled (for free) in their loyalty programs.

JetBlue and Delta use ViaSat. I only fly Delta for the most part and ViaSat was available on all domestic routes I’ve flown except for the smaller A900 that I take from ATL to Southwest GA (50 minute flight). Then I use my free unlimited 1 hour access through T-Mobile with GoGo ground based service.