971
xkcd #2862: Typical Seating Chart
(imgs.xkcd.com)
Alt text:
Now that airlines have started adding wheel locks to their drink carts, less than half of flights have one accidentally fall out through the hole.
I believe it is also meant to catch agrathean sperm whales and bowls of petunias.
Oh no, not again.
Really though you never know what you'll encounter six miles up, but you can be prepared to catch it