Thanks for the inspiration. Based on this I was able to find a working solution.
Maybe it will be helpful for others:

/* iPad Portrait */
@media screen and (min-device-width: 481px) and (max-device-width: 1024px) and (orientation:portrait) {
.avia-section {
background-attachment: scroll !important;
}
}

/* iPad Landscape */
@media screen and (min-device-width: 481px) and (max-device-width: 1024px) and (orientation:landscape) {
.avia-section {
background-attachment: scroll !important;
}
}