In A Voice in the Wilderness, parts 1 and 2, strange things are going on down on Epsilon III, the planet which Bablyon 5 orbits. Sinclair and Ivanova go down to investigate.
But since these two are the most senior officers aboard Bablyon 5, why are they sent? Since they have so many other duties to perform to keep the station running, why not send other people whose absence will be less disruptive?
Showrunner J. Michael Straczynski conversed online with fans during the early days of the show. A few people asked this question, and he responded with a clear answer:
A First Contact situation is one unlike any other: you don't want junior officers around to screw it up. Remember, the Earth/Minbari War began when a First Contact situation got screwed up. EA's [Earth Alliance's] policy is that it's better to risk two people than a full war, and those two people have got to be command-level personnel. Soldiers get killed; it happens. And yeah, you can leave a backup person at the shuttle ...but what if he's the one to make actual first contact? You're screwed. Ivanova and Sinclair have been trained in this; in "Soul Hunter," Sinclair makes reference to the rules of First Contact Protocol. If you like, I'll elaborate on this in some future episode.
I imagine that part of it is not only that they need someone who is trained, but also someone with the authority to negotiate any terms. Remember, this all started because weapons were fired on Babylon 5, and sending someone who then has to report to their higher ups introduces a delay that puts the station at additional risk.
