DM, start by accepting the harsh reality that 32% of those boarding the economy cabin on 803 *don't* survive. The odds are not good. About all you can do to improve the odds is secure an exit row seat. That one move can get you to 90%+ survivabilty, while making it to either of the premium cabins virtually assures you will survive.

I've done that flight 5 times and have it coming up in a few days. Upgrades have cleared for all segments so I'm good. Last November I did fly 803 to Singapore in an exit row for the first (hopefully last) time. All kidding aside I was kind of dreading it, but in the end it worked out. Definitley not enjoyable but entirely survivable with the exit row. So that's the critical piece for economy - get the best possible seat. Good luck.