The Corsair's navigator is frustrated; he does not know where he is, so he takes another sun-sighting as soon as he gets a clear shot. I like the little details in this movie- note the crack in the atrodome from someone probably whacking the octant into it.
The process of using the thing is well-shown here, too... as much as I would love to learn how to do this, it's obvious that GPS represents real progress to benefit those who invent such things: people who are lazy, but very bright.

Soon the navigator has a better idea of where they are, but it's not enough to pinpoint them once the search party is within range for a quick broadcast. There is a lot of ground to cover, and time is running short for the stranded crew.
The pilots now have nothing much to do, but the radio man, like the navigator, is still on duty. He's explaining here the use of the emergency transmitter, a very handy device (known as a "Gibson Girl" because of... well, just Google it if you don't know.

It's hard work revving up the flywheel inside this thing to generate power; every man takes his turn, and they'll have to keep doing it all day, every day, until they're rescued.
Next: Part 6