3 ms·

I had to read that sentence a dozen times to figure out what they were saying. It's probably the first time I've ever seen the phrase "Cabin Pressure Altitude"

I had to read that sentence a dozen times to figure out what they were saying. It's probably the first time I've ever seen the phrase "Cabin Pressure Altitude" - Might make sense in a technical aviation document, but I'm guessing 99% of readers would have had an easier time with "A lower flight level to increase cabin pressure."

bdamm 8y ago
The terminology works very well for pilots, because pilots have got it locked into their brain that higher altitude == lower pressure. Pilots also have fairly extensive rules for how and when they can fly at a given "altitude", defined in terms of the atmosphere the pilot is breathing, so it makes sense to think of the cabin's pressure as "altitude". "Pressure" is not something you can really feel beyond the extremes, but altitude is something you really understand every second of every flight. If you're a pilot.
- jdietrich 8y ago
  Even as a non-pilot, 8,000ft is more intuitively meaningful than 10.88psi or 0.74atm.
  - derefr 8y ago
    As a structural engineer, I feel like it'd be "obvious" to default to megapascals (MPa) here. Maybe it's less relevant for planes, but if you're in, say, a submarine, then there's a direct relevance of the pressure of the air inside the sub, the pressure of the water outside the sub, and the tensile strength of the hull of the sub—and they're all measured in MPa (or sometimes GPa.)
    - bdamm 8y ago
      For airliners altitude pressure isn't structural (any more) beyond tracking pressurization cycles. It's much more about the human factors; passenger comfort (and sometimes injuries such as burst ear drums), and the aeromedical factors of oxygen saturation within the pilots' bloodstreams.
  - heelix 8y ago
    8000' is pretty comfortable from an air pressure perspective. In practice, I'll do 9,500' or so for longer durations in an unpressurized plane in the daytime. Lower at night unpressurized. Wonder if the event was at night. Flying (as pilot), you require supplemental O2 if you are over 12,500' pressure for 30 min, 14,000 it is a must. Seeing them set the internal pressure to half of the 'you must wear a mask' levels makes sense.
- sokoloff 8y ago
  Pilots are also naturally going to parse that as (cabin (pressure altitude)) rather than (cabin pressure) altitude [or any other grouping].

bdamm 8y ago

The terminology works very well for pilots, because pilots have got it locked into their brain that higher altitude == lower pressure. Pilots also have fairly extensive rules for how and when they can fly at a given "altitude", defined in terms of the atmosphere the pilot is breathing, so it makes sense to think of the cabin's pressure as "altitude". "Pressure" is not something you can really feel beyond the extremes, but altitude is something you really understand every second of every flight. If you're a pilot.

jdietrich 8y ago
Even as a non-pilot, 8,000ft is more intuitively meaningful than 10.88psi or 0.74atm.
- derefr 8y ago
  As a structural engineer, I feel like it'd be "obvious" to default to megapascals (MPa) here. Maybe it's less relevant for planes, but if you're in, say, a submarine, then there's a direct relevance of the pressure of the air inside the sub, the pressure of the water outside the sub, and the tensile strength of the hull of the sub—and they're all measured in MPa (or sometimes GPa.)
  - bdamm 8y ago
    For airliners altitude pressure isn't structural (any more) beyond tracking pressurization cycles. It's much more about the human factors; passenger comfort (and sometimes injuries such as burst ear drums), and the aeromedical factors of oxygen saturation within the pilots' bloodstreams.
- heelix 8y ago
  8000' is pretty comfortable from an air pressure perspective. In practice, I'll do 9,500' or so for longer durations in an unpressurized plane in the daytime. Lower at night unpressurized. Wonder if the event was at night. Flying (as pilot), you require supplemental O2 if you are over 12,500' pressure for 30 min, 14,000 it is a must. Seeing them set the internal pressure to half of the 'you must wear a mask' levels makes sense.
sokoloff 8y ago
Pilots are also naturally going to parse that as (cabin (pressure altitude)) rather than (cabin pressure) altitude [or any other grouping].