So I open the bag up all the way, and I put a quilt inside it. Usually the first time I put the quilt around the machine and then slide it into the bag.
And then it zips up all nice. And it has nice long (padded) straps so I can easily put it on my shoulder or on top of a suitcase to travel with it.
A few tips for traveling with it (through an airport). Take it out of the bag when going through security and put the machine in a bin by itself. Now there have been sometimes they don't care when it's in the bag, but there are sometimes they do. So it's just easier to put it in the bin beforehand.
Expect to have people ask you about it! I always have good conversations with TSA employees about the machine, they usually reminiscing about a machine someone in their family had.
I have not actually used this to sew at a gate (usually electric plugs are hard to come by) but it would be a possibility. But once I get to my destination she usually comes out of the bag and is set up.
I don't just use this for air travel, it's handy when I am doing my craft fairs, or sewing nights, because it's easy to take a long.
If you have any questions about traveling with a (singer featherweight) sewing machine please let me know and I will do my best to tell you my experiences!