Doug_Or From United States of America, joined Mar 2000, 3162 posts, RR: 4 Posted (9 years 11 months 4 weeks 13 hours ago) and read 1790 times:
I've been studying for the ATP written, and some of the part 121 FARs strike me as a little strange. they make refrence to aircraft being required to have O2 for 10% of the passengers in certain situations. Am i correctly reading this to mean that O2 only needs to provided to 1 in 10 passengers?!? if so, why bother?
Mjzair From United States of America, joined Nov 1999, 392 posts, RR: 1 Reply 1, posted (9 years 11 months 4 weeks 9 hours ago) and read 1728 times:
I am studying for the JAA ATPL, and the text refers to a 10% rule, this states that the total number of oxygen dispensers has to exceed the number of cabin attendent and passanger seats by 10%.
Could this be what you are refering to?
Flyf15 From , joined Dec 1969, posts, RR: Reply 4, posted (9 years 11 months 3 weeks 6 days 7 hours ago) and read 1557 times:
I can't say I've read deeply into this, but I'd assume they mean for planned flights at these cabin pressure altitudes -- ie: not emergency oxygen. Makes sense, below 14000ft I could see about 10% of the pax needing to breathe oxygen. Below 15000ft, I could see about 30% needing it. And above 15000, I could see enough needing it that it should be carried for all.
B747skipper From , joined Dec 1969, posts, RR: Reply 5, posted (9 years 11 months 3 weeks 6 days ago) and read 1519 times:
When the US FAR 121 mentions 10% or 30%... it means the amount of oxygen required for the physiological requirements of the total amount of passengers... at low cabin altitude, 10% of the physiological needs for the total amount of passengers would be sufficient... at higher altitudes, it is based on 30%, and above FL 150, it is for everyone...
Just for your information, do not think that "passenger oxygen masks" are of much help at high flight levels in case of loss of pressurization... it is doubtful that such masks could sustain physiological human requirements above say some 25,000 feet... These flimsy masks are just good enough to give oxygen for passengers in an emergency descent, most emergency descents procedures mention descents to 14,000 feet...
We have charts with flight time and number of passengers for minimum oxygen requirements in the aircraft operating manual...
Happy contrails -
B747skipper From , joined Dec 1969, posts, RR: Reply 7, posted (9 years 11 months 3 weeks 5 days 22 hours ago) and read 1484 times:
Read your 121 regulations, for oxygen, it deals (fine print) "Oxygen for SUSTENANCE" or "Oxygen for emergency descent" (if I remember well), quite different requirement... excuse this old fart, I am in a hotel, dont have my 121 regs handy...
MxCtrlr From United States of America, joined Nov 2001, 2485 posts, RR: 40 Reply 8, posted (9 years 11 months 3 weeks 5 days 21 hours ago) and read 1461 times:
Also remember, if your aircraft has gotten into a situation where O2 is required, there is also most likely, an emergency descent in play. The likelihood that you will require oxygen for a full 30 minutes is remote at best. More like 10 minutes (and, in some of the emergency descents I've been on, more like 5 minutes). Plus, some of the passengers just sit and stare at the mask when they drop. The F/A's have to put them on the pax for them!
Freight Dogs Anonymous - O.O.T.S.K.
DAMN! This SUCKS! I just had to go to the next higher age bracket in my profile! :-(
Viflyer From US Virgin Islands, joined May 1999, 493 posts, RR: 0 Reply 9, posted (9 years 11 months 3 weeks 5 days 17 hours ago) and read 1428 times:
The 10% rule does bring up some interesting questions though. With the company work for the only A/C that doesn't have a mask for every pax is the ATR's, If I remeber correctly the 42 has 5 masks, 72 had 5 under each F/A's jumpseat (two F/A's on the 72) so a total of 10, and the 72-212A had overhead drop down masks from the overhead but it was triggered by the FO's side of the cockpit and there was only a total of 18-15 (I think, it's been a while since I did a ATR trip). But the question that always comes up in training is who gets the masks. Usually answer is that it's the F/A's judgement but the standing joke is who ever is willing to give cash, cars, and rolexs to the F/A. But honestly it's sort of a non-issue because we don't fly high enough, long enough on the ATR that getting below 10,000 will be a problem (average FL is in the neighborhood of FL120 to about FL180). By the time the F/A breaks out the mask, distrubutes them, and the pax put them on, i'm pretty sure the crew would have us well below 10,000. The highest i've been on the ATR is FL 250 but that was one flight (over a 3 year period) and by the time we got to FL 250 it was almost time to begin the decent.
B747skipper From , joined Dec 1969, posts, RR: Reply 10, posted (9 years 11 months 3 weeks 5 days 10 hours ago) and read 1375 times:
Airplanes flying below FL250 (or so certificated) do not require oxygen system. Further, on ANY flight under US FAR 121, a briefing to passengers about oxygen is NOT required if flying below FL 250...
Most air carriers make an oxygen briefing no matter what altitude, because the cabin attendants have a "standardized" briefing for all flights... sometimes they include an "overwater" briefing, even if flying only in the Sahara...
The more the briefings, the less the interest of passengers... unfortunately. Briefings should be short and clear to keep their interest...
FrequentFlyKid From United States of America, joined Nov 2001, 1197 posts, RR: 1 Reply 11, posted (9 years 11 months 3 weeks 4 days 21 hours ago) and read 1318 times:
Correct me if I am wrong, but my understand of the oxygen masks was to sustain the life of a passenger, not to necessarily keep them conscious. I know that's a little off-topic, but I've always wondered that.
B747skipper From , joined Dec 1969, posts, RR: Reply 12, posted (9 years 11 months 3 weeks 4 days 20 hours ago) and read 1314 times:
You are quite correct, the passengers O2 masks are basically worthless, they just will help keep them "alive" (and scared) during the 2 to 3 minutes emergency descent to 14 or 15,000 feet... be aware also that transport category airplane are certificated to their maximum flight level so that they can maintain a cabin altitude equal to or better than 8,000 feet.
Pilots masks, although a little more efficient, can do OK to about 30 to 32,000 feet (they are not "pressure systems" like you have in fighters), higher than that, again, they will assist pilots for the emergency descent... just that... a lot of pilots flying high altitude airplanes should be reminded of that fact...
With USA airlines (121) when a pilot leaves his station, the other pilot is required to wear his mask... good point... not many foreign airlines do require this... However many foreign countries require actual "pressure chamber O2" physiological training, for pilots operating aircraft above FL 250... in the USA, "just watching a video" about it, is... sufficient...
It is considered that "unpressurized airplanes" can be flown without oxygen to about 10 to 12,000 feet (USA insists for lightplane pilots not to fly higher than 10,000 feet without oxygen)... I have a Bolivian pilot friend who lives in LaPaz, and flies a Cessna 185... he does not wear oxygen unless exceeding 15 or 16,000 feet - but is body is accustomed to that altitude. La Paz airport is 13,500 feet high...
I go to the pressure chamber every 2 years for recurrent training... one thing I have learned, if I have to get the death penalty, this would be my choice for execution... you feel good, very good, and then... nothing...
B747skipper From , joined Dec 1969, posts, RR: Reply 15, posted (9 years 11 months 3 weeks 4 days 15 hours ago) and read 1260 times:
Dear Glenn -
Like Doug mentioned, per row of "3 seat units" there are 4 masks... the larger "center aisle units" (wide bodies) of 4 or 5 seats have 5 or 6 masks...
No matter what - as a parent, how much you love your child, take YOUR mask first THEN give the child the mask... if you do the opposite, you may faint, his mask will fall, he will faint too... so, first SAVE YOURSELF (in ANY emergency) so you can help others...
Jetguy From , joined Dec 1969, posts, RR: Reply 16, posted (9 years 11 months 3 weeks 4 days 13 hours ago) and read 1240 times:
This thread reminds me of the famous Southwest Airlines cabin safety briefing...
"Welcome aboard Southwest Flight 124 to Orlando. To operate your seatbelt, insert the metal tab into the buckle, and pull tight. It works just like every other seatbelt and if you don't know how to operate one, you probably shouldn't be out in public unsupervised. In the event of a sudden loss of cabin pressure, oxygen masks will descend from the ceiling. Stop screaming, grab the mask, and pull it over your face. If you have a small child traveling with you, secure your mask before assisting with theirs. If you are traveling with two small children, decide now which one you love more...