A320ajm
Topic Author
Posts: 587
Joined: Sat May 20, 2006 11:57 pm

Decompression Announcement/Procedure

Wed May 30, 2012 11:23 pm

Hey,

I've heard that on some aircraft if a decompression happens which results in the oxygen masks being deployed an automatic announcement is played. Is this true and if so, what does it say? Does it warn of the rapid descent? (which I'm sure must scare the hell out of most passengers not familiar with this procedure)

Also, on a related note, my girlfriend asked me the following questions knowing I was a plane geek and I couldn't answer them: "What happens in a decompression when you have a baby/child on your lap, as there are 4 people in an aisle? And, do babies/children get a smaller mask as surely an adult one would be too big for them?"
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Mir
Posts: 19108
Joined: Mon Jan 05, 2004 3:55 am

RE: Decompression Announcement/Procedure

Wed May 30, 2012 11:32 pm

Quoting A320ajm (Thread starter):
"What happens in a decompression when you have a baby/child on your lap, as there are 4 people in an aisle?

There is an extra mask in certain compartments (they might be limited to one side of the airplane, in which case no lap children may sit on the opposite side). This is why two lap children can't sit in the same row.

Quoting A320ajm (Thread starter):
And, do babies/children get a smaller mask as surely an adult one would be too big for them?"

No, it's just the standard mask. They're not designed to seal tight, as they're not intended for long-term use, just enough to keep people going until the airplane can descend to a breathable altitude.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
m11stephen
Posts: 372
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RE: Decompression Announcement/Procedure

Wed May 30, 2012 11:33 pm

Quoting A320ajm (Thread starter):
I've heard that on some aircraft if a decompression happens which results in the oxygen masks being deployed an automatic announcement is played. Is this true and if so, what does it say? Does it warn of the rapid descent? (which I'm sure must scare the hell out of most passengers not familiar with this procedure)

I think it's a customer option but the announcement will say something like, "Ladies and gentlemen please sit down and fasten your seat belts immediately. We have experienced a sudden loss of cabin pressure. Remain calm and pull the mask towards you, place the mask over your noise and mouth and breath normally. Do not remove the mask until advised by a crewmember." That isn't the exact verbiage but it is generally what the announcement says. Keep in mind that during an explosive decompression it will be very hard to hear anything.

Quoting A320ajm (Thread starter):
Also, on a related note, my girlfriend asked me the following questions knowing I was a plane geek and I couldn't answer them: "What happens in a decompression when you have a baby/child on your lap, as there are 4 people in an aisle? And, do babies/children get a smaller mask as surely an adult one would be too big for them?"

There are certain seats on every airplane that are equipped with an extra oxygen mask for an infant. Agents and F/As are trained on which seats to put parents with lap children into so that there will be sufficient oxygen for everyone in the event of a decompression. No, there are no special masks for infants.
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tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Decompression Announcement/Procedure

Thu May 31, 2012 1:00 am

Quoting A320ajm (Thread starter):
I've heard that on some aircraft if a decompression happens which results in the oxygen masks being deployed an automatic announcement is played. Is this true and if so, what does it say?

Yes, it's true. It's a customer option (both to have it, and what it says). The text is generally as m11stephen described, but it can be anything.

Quoting A320ajm (Thread starter):
Does it warn of the rapid descent?

Generally not. By the time the announcement plays the rapid descent should already be in progress.

Quoting A320ajm (Thread starter):
(which I'm sure must scare the hell out of most passengers not familiar with this procedure)

It's not nearly as bad as most people think. I've done 4 or 5. The transient as you initially pitch over can be a bit aggressive if done on autopilot but, once you're into the descent, it looks/feels mostly like an approach with the speedbrakes up.

Tom.
 
Mir
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 1:26 am

Quoting tdscanuck (Reply 3):
The transient as you initially pitch over can be a bit aggressive if done on autopilot

Do you mean if NOT done on autopilot? We're not allowed to use the autopilot for the initial pitch down because it's not aggressive enough.

-Mir
7 billion, one nation, imagination...it's a beautiful day
 
mffoda
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 1:35 am

Quoting A320ajm (Thread starter):
Does it warn of the rapid descent? (which I'm sure must scare the hell out of most passengers not familiar with this procedure)

If its an explosive decompression, you won't even notice the descent...  
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tdscanuck
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 1:54 am

Quoting Mir (Reply 4):
Do you mean if NOT done on autopilot?

No, I meant done on autopilot. The most common technique I've seen is to put the autopilot in FLCH to the lower altitude, pull the throttles to idle, put up the speedbrakes, and dial the speed up to Mmo. Since the autopilot will go into FLCH SPD it's holding speed on pitch, and it's trying to go faster with no thrust and the speedbrakes hanging out...the only way to do it is to pitch over hard.

I've done it twice on autopilot, it's plenty aggressive. I've never seen a crew pitch over that abruptly.

Quoting Mir (Reply 4):
We're not allowed to use the autopilot for the initial pitch down because it's not aggressive enough.

News to me; might be a change in pitch laws between what I've flown and what you've flown.

Tom.
 
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Starlionblue
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 5:16 am

What about getting out of the lane/airway/corridor? Would the pilots not be well served in moving to the side a bit? Also, if you rolled a bit before pitching down, would that make the maneuver feel less aggressive?
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tdscanuck
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 1:04 pm

Quoting Starlionblue (Reply 7):
What about getting out of the lane/airway/corridor? Would the pilots not be well served in moving to the side a bit?

That would certainly be a good idea; when I've done it it's been for test and we pre-coordinated with ATC so we didn't have to worry about separation. In the real event, getting a mile to the side of the track would just make good sense until you can notify ATC of your intentions.

Quoting Starlionblue (Reply 7):
Also, if you rolled a bit before pitching down, would that make the maneuver feel less aggressive?

If you rolled while pitching that would help (the positive g from the roll would offset the lower g from the pitchover) but I'm not sure an autopilot would coordinate that well and I'm not sure the flight crew wants to be trying to do a coordianted roll/pitchover while accelerating, putting the boards up, donning oxygen, and idling the engines. But if the crew has the bandwidth to do it it ought to work.

Tom.
 
Tod
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 2:40 pm

Quoting A320ajm (Thread starter):
And, do babies/children get a smaller mask as surely an adult one would be too big for them?"

The FAA requires 10 percent extra masks spread evenly throughout the cabin.
The official reason is to facilitate flight attendants getting to their oxygen provisions.
In the case of supplemental oxygen, the FAA choses to ignore the existance of babies on board.

That said, most airlines prefer to have their planes provisioned to facilitate some babies.

As an engineer laying out oxygen box locations, I always locates some of the required excess at the seat rows with bassinet provisions.
 
bwaflyer
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RE: Decompression Announcement/Procedure

Thu May 31, 2012 11:29 pm

on bmi Airbus aircraft, an automatic PA will play when the masks are deployed. The text is as follows;

“Ladies and Gentlemen, the aircraft has just suffered a decompression and the emergency oxygen
system is being activated. Remain seated, fit your oxygen mask and breathe normally. Secure the
mask by placing the elastic over the back of your head. You must fit your own mask before assisting
others.
Any smell of burning is normal following the activation of the chemical oxygen generators.”

It lasts 27 seconds, and plays 20 times (lasting 9 minutes) unless cancelled by the crew.
 
Markhkg
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RE: Decompression Announcement/Procedure

Fri Jun 01, 2012 1:24 am

Here is the decompression announcement from Turkish Airlines. First in Turkish, then English.

http://www.youtube.com/watch?v=wTwU2dt6YP4

You might also have cabin crews pre-drilled to shout, "MASKS ON, FASTEN SEAT BELT" or something to that effect during a decompression.

On Ryanair and some other carriers, the flight crew will actually announce on the cabin PA, "EMERGENCY
DESCENT" three times per their decompression emergency descent checklist.

[Edited 2012-05-31 18:24:34]
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pilotpip
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RE: Decompression Announcement/Procedure

Fri Jun 01, 2012 3:43 pm

Our 170s have the seatbelt sign tied to the mask deployment. No announcement. If the loud bang, sudden cold and sinus/ear discomfort aren't enough to tell you something is wrong the 6000fpm descent with full speed brakes will.
DMI
 
fly727
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RE: Decompression Announcement/Procedure

Wed Jun 13, 2012 6:45 am

This is the transcript of our cabin depressurization announcement in the EMB-145. As stated above, it is quite obvious that something is going wrong by means of discomfort in the ears, loudness, water condensation and things flying everywhere. The track is played once the flight attendant can reach the audio panel and after securing herself with her own O2 mask.

"Ladies and gentlemen, your attention. There's been a loss of cabin pressure. Pull the mask towards you, place the mask over your nose and mouth and adjust the strap around your head. Fasten your seatbelt; remain calmly seated with the oxygen mask on."

This announcement is proceeded by the one in Spanish.

RM  
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akiss20
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RE: Decompression Announcement/Procedure

Wed Jun 13, 2012 7:34 pm

Quoting Tod (Reply 9):
In the case of supplemental oxygen, the FAA choses to ignore the existance of babies on board.

Source? I find that hard to believe, but I will if proven so.
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TZTriStar500
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RE: Decompression Announcement/Procedure

Thu Jun 14, 2012 12:54 am

Quoting akiss20 (Reply 14):
In the case of supplemental oxygen, the FAA choses to ignore the existance of babies on board.

This statement is not entirely true as they are accommodated in locations where there are extra masks per the 10% extra requirement. A baby or lap child without a seat must be seated in any area where there are extra masks.
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