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Bad wording on my part since I implied but didn't state the alternative. In my mind, the alternative scenario that would create a depressurization event would b

Bad wording on my part since I implied but didn't state the alternative. In my mind, the alternative scenario that would create a depressurization event would be a small hole or a hole that is not visible from the passenger compartment. I.e., a hole from which a passenger or attendant could not exit the plane.

pengaru 3y ago
I'm no expert, but I've always assumed these pressurized cabins aren't exactly hermetically sealed, so a small invisible hole wouldn't noticeably depressurize the plane. My assumption has been there's always fresh air actively added continuously at a rate that can compensate for such small leaks, and that it's just an automatically regulated thing. Maybe a gauge/alarm visible to the pilots would indicate an out of spec level of fresh air entering to maintain pressure, without actually being a "depressurization event"... But a door-sized hole is a whole (har har) different story. Edit: https://aviation.stackexchange.com/questions/53831/are-pressurized-passenger-aircraft-usually-completely-airtight https://aviation.stackexchange.com/questions/53831/are-press...
- btgeekboy 3y ago
  Your assumption is correct - air is pushed into the cabin by the engines, and the pressure is controlled by an outflow valve. An unanticipated hole, assuming it was small enough, would just be compensated for.
- kayodelycaon 3y ago
  It wouldn’t take much of a hole to depressurize the plane. And unplanned holes in a pressure vessel have a tendency to rapidly get larger.
  - pengaru 3y ago
    > unplanned holes in a pressure vessel have a tendency to rapidly get larger. I suspect that's only an issue on airliners when the hole happens in a window. There's no shortage of search results confirming that something like gunfire on an airliner likely won't depressurize the plane unless it hits a window....
kijin 3y ago
Wouldn't a small hole quickly become a large gaping hole anyway, if it's large enough to affect the cabin pressure? I suppose if the small hole had existed since before takeoff, you could avoid catastrophic damage as the aircraft will not be pressurized at all. I wouldn't call it a depressurization event, though.

pengaru 3y ago

I'm no expert, but I've always assumed these pressurized cabins aren't exactly hermetically sealed, so a small invisible hole wouldn't noticeably depressurize the plane. My assumption has been there's always fresh air actively added continuously at a rate that can compensate for such small leaks, and that it's just an automatically regulated thing. Maybe a gauge/alarm visible to the pilots would indicate an out of spec level of fresh air entering to maintain pressure, without actually being a "depressurization event"... But a door-sized hole is a whole (har har) different story. Edit: https://aviation.stackexchange.com/questions/53831/are-pressurized-passenger-aircraft-usually-completely-airtight https://aviation.stackexchange.com/questions/53831/are-press...

btgeekboy 3y ago
Your assumption is correct - air is pushed into the cabin by the engines, and the pressure is controlled by an outflow valve. An unanticipated hole, assuming it was small enough, would just be compensated for.
kayodelycaon 3y ago
It wouldn’t take much of a hole to depressurize the plane. And unplanned holes in a pressure vessel have a tendency to rapidly get larger.
- pengaru 3y ago
  > unplanned holes in a pressure vessel have a tendency to rapidly get larger. I suspect that's only an issue on airliners when the hole happens in a window. There's no shortage of search results confirming that something like gunfire on an airliner likely won't depressurize the plane unless it hits a window....

kijin 3y ago

Wouldn't a small hole quickly become a large gaping hole anyway, if it's large enough to affect the cabin pressure? I suppose if the small hole had existed since before takeoff, you could avoid catastrophic damage as the aircraft will not be pressurized at all. I wouldn't call it a depressurization event, though.