Summary: First let me state that I love Sennheiser headphones. I have three pair: my original 414s from 30+ years ago, a 965 Ovations and pair of CX 475 earbuds. I am completely sold on Sennheiser, and am a long-time fan. Having said that, these headphones were very disappointing. I originally had a pair of the Rocketfish noise-canceling headphones. They were okay, but I wanted something better, so I swapped them for these Sennheisers.
Summary: These earphones have decent passive noise isolation, but the active noise cancellation is pretty weak, and varies a lot depending on fit. What's worse is the volume is pretty low, so you cannot hear music well in a noisy flight. I had to return mine because of these issues, quite disappointed.