YW, I think you are right that the captain wasn't in the cockpit, but taking his rest period. Can someone tell us again what experience the two FO's in the cockpit had if the captain was taking his break? If it was a pitot static failure it would take a damn good pilot to get through that zone using what he had available. Maybe going to GPS ground speed for a while until they sorted it out. I only did one trip to Sao Paulo, Brazil and that convinced me I didn't want to do any more. You leave your cockpit to have no control for a couple hours would require a lot of confidence in your crew. I had confidence in them but still didn't like it. Only did it once so am not an authority on the subject.