Any chance we can get clarification on the Inmarsat ping business as requested above? Since I understand that a SATCOM service for a cars was not subscribed to then neither the aircraft nor the satellite would be motivated to ping so presumably this relates to voice comms. Unless a time stamp is sent I do not see how a handshake initiated by the a/c would allow signal transit time to be calculated by the satellite.
On another issue is it now understood that the acars shutdown was not the tidy logging off procedure believed up to a few pages back.
On another issue would the a/c have been visible to Vietnam ATC at the time of last voice message.
And finally, following normal protocol, when would first voice contact have been expected with Viet ATC in relation to the time of the OK roger message?
Thank you for your patience!