A few weeks ago, the family flew to Columbus for my sister’s graduation from law school. On the way back, we bought a bottle of Fiji water.
Which I drank.
Because the flight path from Columbus to Baltimore is kind of a rainbow, we went up an down quickly. I finished the bottle of water at the peak of the flight path. I twisted the cap on as hard as possible.
After we hit the ground, my bottle looked like this:
I fairly well sealed the bottle when I screwed the cap on. But the plane is not pressurized to the same pressure as the air at sea level. There, the air pressure is roughly 14.7 pounds per square inch. However, the airplane is pressurized only to between 8 and 11 pounds per square inch.1 The outside air pressure is between 3 and 4 psi. By using a lower pressure on the plane than 14.7, there is less stress placed on the airframe extending its lifetime and it is high enough to not be completely uncomfortable, though your ears may disagree. But as the pressure increases, it grows higher outside the bottle than inside, which was sealed between 8 and 11 psi. So the bottle’s sides cave in as far as the shape of the bottle will permit. And when opened, there’s a delightful whoosh, but instead of carbonation leaking, the bottle is refilling with air.
- Thank you Al Romack for this information. ↩