[jandrese]

It was more confusion. One system was broken, and the alternate was taken out of service. The pilot was then confused because flying with only one sensor was considered acceptable, but he was asking about a both sensors out situation instead. So they did it the old school way with dipsticks, but the conversion formula written on the sheet was wrong because they were in the process of switching. Also, the person who's job it is to get this right didn't exist on the 767 and Air Canada had not finished figuring out how to divvy up the duties when that seat wasn't filled. It's one of those Frogger failures, so many things have to line up just right at this one point in history for the problem to happen. Luckily in this case everyone came out ok.