This is the mission where there's a medical emergency at station A, and the doctors send you to station B to buy medicine and rush it back. Because the medicine in question massed 1 ton apiece (and they needed IIRC 30 tons; anyway there's no reminder at the dockscreen to tell you), I spent *maybe* 60 realtime seconds in the dockscreen at station B figuring out how I was going to make enough room. That's dockscreen time, so way less than regular game time. I failed the mission on the return trip with ~20 light-seconds to go.

I was using the Scorpion from Song's ES mod, which is a fairly fast ship, and I'd installed a Titan drive on it but was using 4x heavy armor (-.02c apiece). All in all a fairly fast ship; if I'd been using a freighter of any type there's certainly no way that mission could have been completable.