The only time I have had a problem was on a UAX flight from IAD-LGA earlier this year. The FA said she knew nothing about a flight mode and they were trained that it had to be completely off according to the FAA. I turned it off and told her that she should check because either her recollection of her training or the training itself was wrong because that was not an FAA policy. She told me that she would check because I was the second person to tell her that. The first was a mainline UA pilot. I think there should be a message there, apart from my flying 100K+ miles per year on AA to minimize flying on UAX to IAD that is.