"no fly" time

[Gene_Hobbs]

By normally you mean 8,000 feet?

This is an interesting topic that has been looked at quite a bit given the number of people with cardiac and pulmonary disorders. (This is by no means a complete list, just a couple that get used)

Kelly et. al. Directly measured cabin pressure conditions during Boeing 747-400 commercial aircraft flights. Respirology. 2007 Jul;12(4):511-5. PubMed ID: 17587417

Study recorded cabin pressures and all flights fell within 8,000 foot limit set by the FAA. 45 flights one aircraft and three airlines.

Cotterll. Altitude exposures during aircraft flight. Flying higher. Chest. 1988 Jan;93(1):81-4. 3335171

Study showed a wide range with a mean cabin pressure of 6,214 feet (1894 m) and a max cabin pressure of 8,915 feet (2717 m). 204 flights on 16 different aircraft, and 28 airlines.

The 8,000 foot limit is an FAA limit and last I heard, airlines in international air space could make their own call as to pressure to hold (not a pilot, just a researcher so PLEASE correct me here). I know there was an abstract at a Aerospace Medical Association meeting a few years back that tracked trans-atlantic flights but I can't find it.

 

[Thalassamania]

This is an interesting topic that has been looked at quite a bit given the number of people with cardiac and pulmonary disorders. (This is by no means a complete list, just a couple that get used)

Kelly et. al. Directly measured cabin pressure conditions during Boeing 747-400 commercial aircraft flights. Respirology. 2007 Jul;12(4):511-5. PubMed ID: 17587417

Study recorded cabin pressures and all flights fell within 8,000 foot limit set by the FAA. 45 flights one aircraft and three airlines.

Cotterll. Altitude exposures during aircraft flight. Flying higher. Chest. 1988 Jan;93(1):81-4. 3335171

Study showed a wide range with a mean cabin pressure of 6,214 feet (1894 m) and a max cabin pressure of 8,915 feet (2717 m). 204 flights on 16 different aircraft, and 28 airlines.

The 8,000 foot limit is an FAA limit and last I heard, airlines in international air space could make their own call as to pressure to hold (not a pilot, just a researcher so PLEASE correct me here). I know there was an abstract at a Aerospace Medical Association meeting a few years back that tracked trans-atlantic flights but I can't find it.

My understanding jibes with yours, 8,000 is FAA, most flights are really closer to 6,000, but there are no guarantees, esp. foreign carriers on international routes.

 

[nereas]

As all of you esteemed respondents are certainly aware, any pressurized cabin can suddenly lose its pressurization. They warn you about that on the plane, when they talk about the little yellow O2 bag.

If it does, for whatever reason, and if you have an N2 load in your blood and tissues, then you will be SOL, if it happens.

That is why 24 hours before flying, or 48 hours in the case of deco diving, is a great rule, and should be followed.

I also would like to second Thal's advice about staying on one island. That is what I always do as well.

This has been a fun thread, with stimulating responses. I have enjoyed reading them all.

 

[Bismark]

As all of you esteemed respondents are certainly aware, any pressurized cabin can suddenly lose its pressurization. They warn you about that on the plane, when they talk about the little yellow O2 bag.

If it does, for whatever reason, and if you have an N2 load in your blood and tissues, then you will be SOL, if it happens.

That is why 24 hours before flying, or 48 hours in the case of deco diving, is a great rule, and should be followed.

I also would like to second Thal's advice about staying on one island. That is what I always do as well.

This has been a fun thread, with stimulating responses. I have enjoyed reading them all.

Of course you are correct, but to me that seems a tad on the excessive side in terms of risk assessment. I am not sure what the occurence's of this are, but even when I was flying in the military I was not aware of any incidences on a first or second hand basis. (scratches his head and trys to remember.......) Thalassamania, you seem to have just about every statistic at your fingers, any thoughts here?

 

[Bismark]

One other note, I believe the new Boeing dreamliner (787) has a lower cabin pressure at altitude than almost every other airliner.

 

[Thalassamania]

Of course you are correct, but to me that seems a tad on the excessive side in terms of risk assessment. I am not sure what the occurence's of this are, but even when I was flying in the military I was not aware of any incidences on a first or second hand basis. (scratches his head and trys to remember.......) Thalassamania, you seem to have just about every statistic at your fingers, any thoughts here?

I was wondering the odds myself, I have not been able to find a number, but I have found two such incidents in 2005 (one resulted in a crash, so DCS would have been the least of your concern). These were commercial jets, there was also the well know incident that killed Payne Stewart (the golfer) back in 1999, which was a Lear Jet.

 

[limeyx]

As all of you esteemed respondents are certainly aware, any pressurized cabin can suddenly lose its pressurization. They warn you about that on the plane, when they talk about the little yellow O2 bag.

At least I get some free deco gas in this case

 

[Bismark]

After thinking back as much as I could, I recall one CF-18 pilot going down on the west coast and it was suspected that it was an oxygen system malfunction. As you know, pilots in high performance aircraft always breath supplied gas through a mask an explosive decompression incident at 40,000 may be loud and scare the s**t out of you it most likely wouldn't be a deal breaker. That is unless you are Tom Cruise in Top Gun and you have to take your mask off to get a better camera angle.............. I actually think he might be too short to reach the pedals in most high performance aircraft anyways........;-)

 

[bleeb]

I'm not Thal, but off the top of my head, I have a (very) vague recollection of a US NTSB/FAA statistic of 1 in 100,000 flights having a severe pressurisation problem. Don't know if that's rapid decompression, or just any significant problem including failure to pressurise on takeoff.

In my lifetime, I've had one flight delayed, because the incoming plane cracked a window during dinner and lost pressure.

And to answer the other question, yes one of Boeing's selling points for their new 787 is pressurisation to 6000' rather than 8000'. Apparently it was a significant engineering challenge because of the greater pressure differential.

 

[Charlie99]

Luckily, I haven't been on any planes that lost pressure, but I have been on a plane that was purposefully depressurized to just slightly over 10,000' altitude to make it more likely that a cargo door that was ajar would stay in place.

As the Maui to SFO flight was diverting over to Honolulu, the pilot explained to passengers that they might feel a bit faint because he had reduced the pressure to just below the automatic trigger point of the emergency O2 system at 11,000'.

I had done a night dive about 14 hours before the flight.