First time in years! Sept 30 UA 946 IAD-AMS 767-300 (N653UA): Channel 9 available and announced by captain:
There was, however, a persistent high tone noise that drowned out most of the audio so I only listened for a few minutes. Also, I was in seat 21D where I had to put away the entertainment system during takeoff and landing.
I did thank the captain after landing for putting the channel on.