Seems like all you needed in years past was a commercial licence and a second class medical to ride in the right seat on a big plane
And the tiny little detail called a 2 month course with a FAR Part 121 SIC Check Ride including simulator and bounces, basic indoc, emergency pool training, systems, nav course and a bunch of other stuff just to climb into the right seat of an Evergreen DC-8, the hardest 2 months of my life..
