Commercial Fixed Wing
Flight Crew Last 90 Days 30; Flight Crew Total 3000; Flight Crew Type 1000
Other / Unknown
Flight Deck / Cabin / Aircraft Event Illness / Injury
Flight Crew Diverted; Flight Crew Landed As Precaution
Human Factors
I was jumpseating home from vacation.  Approximately an hour after takeoff; the Captain asked me to come forward and indicated that the First Officer appeared to be in physical distress.  This was indeed the case; in a span of 2-3 minutes; I witnessed 2 periods of incapacitation/non-responsiveness from the First Officer with each episode lasting approximately 20-30 seconds.  The First Officer was also sweating profusely.  I assisted the First Officer from the operating seat to a jumpseat and gave him water.  I then occupied the First Officer seat (I am a qualified Captain on the aircraft) and assisted the Captain in a divert to the nearest airfield.  We were met by EMT personnel at the gateway.
At FL350 in cruise flight both crew members were eating the catering and having conversation. The Captain was the Flying Pilot. We had a Company pilot jumpseating who was current on this aircraft type. I noticed the First Officer was sweating profusely. I asked him if he was OK and he didn't respond immediately. He appeared to have lost consciousness for about 5 seconds. He then became alert and coherent. We were talking about what had just happened and it happened again. I called to the jumpseater for help. The First Officer was able to get out of the right seat and sit in the jumpseat. The jumpseater moved to the right seat and helped with the normal cockpit duties. I advised ATC we needed to divert for a medical issue and decided on the closest airport. We communicated with Dispatch about the divert and needing an ambulance waiting at the gateway. The First Officer appeared normal at this point. He was alert; sitting up in the jumpseat; conversing logically and appropriately. I didn't declare an emergency. At this point we had a stable situation. We landed and the First Officer walked off the airplane and was taken to the hospital.
B767 Captain and a company jumpseat Captain describe a medical diversion when the First Officer becomes unresponsive at FL350. After gate arrival the First Officer is able to walk off the aircraft.