No sewing necessary. The only tool you need is a pair of scissors.
Or if the airline takes yours, I suppose you could use a piece of broken wine bottle to do the cutting.
Mitch and I sporting our spiffy warm new duds.
Step 1: Cut The Blanket
If scissors, knife, or broken wine bottle aren't options, here's another method:
Lay it on pavement and bang and scrape with a rock until it's mostly cut through, then rip it.