Last year I was flying long haul with a 70 year old F/O who is a check F/O, checking F/O's and S/O's. On this occasion he was checking the S/O. This was a 4 pilot crew, 2 on, 2 off, and during the flight I asked him for 10 left and right of track due weather on the datalink, an exceptionally easy and very routine task. He couldn't do it and while he was in the bunkroom the rest of us are howling with laughter at a guy who should be in a retirement village.