I just had a 6 hour train ride the day before yesterday and an 11 hour flight today ( yes, that sounds terrible, and it certainly was). I could test the ANC quite well: in the train it was generally ok. Intermittent and transient sounds which you have a bit more often on a train ride, were not filtered out very well (didn't expect this anyway). But I was really pleasantly surprised how well the ANC worked on the plane. There you could clearly hear a difference and I guess the engineers at FiiO put en emphasis on exactly this sound environment. I catched myself using ANC for nearly the whole flight.