Used it a few times and very hit and miss for me. One time on the way from SJC to SEA, I was able to hold a VoIP call over VPN with no issue, to my surprise. I figure they dont allow VoIP call so they would disrupt continueous data stream but as soon as I VPN'ed in, the probelm went a way. I think there is traffic monitor system can't decipher or discriminate VPN data. However, on the way back from SEA to SJC, I couldn't even sync Outlook successfully. I used a Wi-Fi tool to sniff the RF and there were active connections for over 20 systems, probably more than system can handle. My guess is it will be hit and miss depend on how many active users are on the same flight.