Ive been reading and studying the manuals and have found 90% of all the graphs for the 737-800 <--the model I like to fly, weights are in kg, m, in meters (in the metric system) not in feet and LBS etc. Why is this? The 900 seems to have both. Just seems odd and a hit and miss on the graphs. Any discussion about this or just a known fact and people just have to sit here and convert over to metric system when needed?

When you are an airline, you tell Boeing what units you use and they will do the conversions for you. I guess PMDG did not opt to take that luxury and so they took what was at hand.

Exactly - we took what Boeing presented us. (Same applies to indexed PDFs, color etc) I'm pretty sure the actually design work and stuff is done with the metric units - metric is what's used in professional science and engineering work.

The 737 dates back to the 60s though... imperial units would be used back then, would they not?

 

Have to wonder...

Depends on operator preference and regulatory authorities. Canada for example is still a hodgepodge of metric/imperial units. Some operators are all metric, other are not...kind of a mess.

 

EDIT: Ahh Fabo. Ya it is a good question regarding what the design/engineering work was accomplished with. Being a bit of an Apollo nerd, and all the great engineering and other documentation publicly available...it's interesting to see that NASA work being accomplished with lots of imperial units. It would be interesting what the Boeing guys were using. Honestly, I probably believe that vintage -60's 737 design was probably also accomplished with US/imperial units. My first indication is the materials. It's quite difficult to find a metric size equivalent of .032 aluminium for example. Anybody got some .8128 mm 2024-T3 aluminium out there ;). That and a competitive grudge against a former big red country on the other side of the Bering Strait...which was using metric. :LMAO: