It's a hot jolt of dread in your stomach, the cold sweat breaking out on your palms. You're watching the clouds cruise by from the cabin of the plane when turbulence hits. Usually, it's short-lived. You tell yourself 'everything will be okay'. But British Airways Flight 09 was far from usual. For the passengers and crew aboard, that one terrifying moment would stretch out into the longest 12 minutes of their lives.