Here’s a good example of why you should take your photos in raw format. It was late into sunset one recent evening when I looked out my window. Down below were a doe and fawn white-tail deer. Quickly, I grabbed my camera and took just one photo before they disappeared into the woods. But I didn’t have time to adjust anything so when I looked at the image, it looked like this:
If you look closely, you can barely see the outline of a deer! This was at 1/160 sec., F11 at ISO400; hardly enough to get the job done.
Fortunately, that can be fixed, although one this underexposed is really pushing the process. Here’s how it turned out after adjusting the exposure in Lightroom, plus a couple of other development settings. I notice that that much exposure change sort of limits the effectiveness of some of the other settings.
Now that it is legible, I can see that I’ve seen these two before!
Phill Gibson 
Yep, RAW is definitely the way to go – have a number of examples like your blackout shot above that I was able to pull out what I needed to at least have an image – won’t be a gallery worthy shot with the artifacts, but can pull a save out when you need it.
Yes, I thought that shot was gone at first. Glad it turned out as readable as it did!