Well if you are adventurous enough to try that with American Airlines and the sequestration in place you will be stuck until the next morning 🙁 That's what happened to me yesterday – my 9.20 PM flight from SJC to LAX was cancelled. I always check my flight before I leave but yesterday was quite hectic and I just barely made it to the airport 50 minutes prior just to see my flight red-lined 🙁
American Airlines blamed it on sequestration and the reduced slots in LAX. I'm not so sure. I was re-booked for the 6.50AM flight but I'd have trouble beating L.A. traffic.
So I decided to cancel the whole trip. I did try that online and the BA booking engine was confused as I was past my flight departure time. It simply returned a screen with a form and instructions to wait for an email. I did not wait for it and called Executive Club this morning. The agent redeposited the miles without hesitation and did not even ask for the $40 fee (since I cancelled online).
I really love using Avios for short-haul domestic flights as they basically provide you with a fully flexible ticket. Now I just wish I'd had status on OneWorld or AA 🙂