Because the noise generated from the engines and turbulence actually affect the sound on the movie. Its a shame too since the controller feels so good in the hands, and the d-pad is second-to-none. These seem to be a well made product. We have used the AKG PC160 boundary microphone for two school programs recently with great pickup and sound quality in both situations. especially when you take into account the comfort level my husband enjoys. They shine really pretty in the sunlight and make me feel like a queen even in my lounge wear. That, combined with the arch support, is a killer for me and my back/knee issues. but theyre very touch sensitive so when the water touches them or even rain on the outside it changes the volume or pauses the music. Which takes a little while because of how much power it stores. Was looking to replace my old faithful sandals that I had bought at Payless (Yes, payless.