Some time ago I was on a United flight flying from MEX to LAX. The cool thing about UAL is that you can listen to ATC on the in flight entertainment system. In the middle of the flight the pilots started asking Mazatlan center to deveate because of weather. ATC never responded, and the pilots keep on calling. After a few minutes the pilots just said, they were turning, with out any approval from ATC. Is this legal? I am insturment rated and have not heard about this. Well, obviously it is legal but why is it legal? Do the pilots just use TCAS to see other traffic or what?