I will check in future if there are official procedures in that case, however, personally, if I have an OXY ON light that light up, without any other advice (to have oxy on you need 14000ft of cabin altitude) I think that I will firstly put the mask as a security feature, then check what is going wrong because it is something strange that the 10000ft warning has not sounded.

With oxy mask on, in case of no hypoxia, finding that the cabin pressure is ok is something that needs seconds.

Then, found that it is a false warning, I will do the normal descend contacting the ATC....

With masks out I would prefer to land ASAP.

I have to respectfully disagree with you Fabo :) Keep in mind though that I am disagreeing on the basis of my limited knowledge of "procedure" in this case and going on what I see are absolutes, i.e. consequences... I hope that for this thread an actual pilot familiar with the required procedures, or that might even have knowledge of such a situation, will chime in :)

 

I received the warning indication "Oxygen Masks Deployed" now, since this is a sim, I can't have the first officer get up and check if the masks are actually deployed, or even call a flight attendant and ask them what's up? :) and that would take what might have been valuable seconds anyway (If it was actually an emergency), so for the sake of the sim, I have to make the assumption that ALL of the mask are actually deployed (wether as a fault, or for a specific reason that for some reason wasn't being indicated in the cockpit) My thinking process is that since there was no alarm and only a silent "Master Warning" light and it took me about another 2 minutes to track down why the caution even came on in the first place that if the cabin was really losing pressure, I just wasted a LOT of time... Trying to think inside the sim also I would expect that at least for a little while no cabin crew would contact the flightdeck if the masks suddenly deployed because they would assume "Emergency" and the last thing you would want to do in a real emergency is distract the flight crew with yet another annunciation light and sound just so you can ask "what's going on up there?"

 

Another absolute is that if I was on a plane, and the oxygen masks dropped out of the upper panel, I would pull on the cord in about .5 seconds, as would probably half the people in the plane, its what you're clearly told to do, and this would be probably a full 30 seconds before the flight crew could say, "Ummm, the masks being deployed might be a mistake everyone, PLEASE do NOT pull on the mask cords!" :) And even if they announced BEFORE the masks dropped, not to pull on them, I would bet my house that SOMEONE on the plane would yank on one :)

 

Correct me if I'm wrong, but I see only two situations here...

 

1. Highest probability: The masks deployed as a fault and everything otherwise was fine, so stay calm, investigate first, while sedately and routinely reducing altitude to < 10,000. Risk if completely incorrect? Death

 

2. Lowest probability: The masks deployed for a specific reason; there was no indication visible or audible in the cockpit possibly due to the fault affecting both systems, rapid emergency descent to <10,000. Risk if completely incorrect? scared and angry passengers, extra maintenance for the aircraft, and enraged management.

 

I think I would choose 2 and as Ripley said in the movie, Aliens, "You can bill me!" :)

 

I reserve the right to accept that according to procedure, I could be COMPLETELY wrong, but I just have to say honestly that my interpretation sounds like a pilot on the actual plane, and your's kind of sounds like management looking to not incur unnecessary monetary cost :) Totally NOT a dig against you, its just that I've recently gotten kind of emotionally attached to the simulated well being of the lives on my simulated plane... In the presence of confusion, or conflicting information, I assume hypoxia, and will go for the "crazy" safety manuever! Unlike the Helios Airlines pilot who kept saying "That is not what I am asking! I am asking why is my configuration alarm sounding!" as an incessant reply to the flight operations technician saying, "Can you confirm the position of your cabin pressure switch!" because the pilot and copilot were already suffering the disorienting effects of hypoxia :(

On the oxygen panel displayed above there are three deployment options:-

1. Below a cabin altitude of 14,000ft the crew can pull either the red or green knob to manually activate the masks.

2. Above a cabin altitude of 14,000ft the masks are activated automatically, the green knob pops out and the flow indicator is activated.

3. Above a cabin altitude of 17,000ft the masks are activated automatically, the red knob pops out and the flow indicator is activated.

 

So in cases 2 and 3 the oxygen auto presentation, cabin height gauge and altitude warning horn are all activated by the same single source. So it's very unlikely that there would not be agreement between them all.

Case 1 is generally reserved for therapeutic oxygen therefore the crew know that a mask or multiples thereof have been presented.

 

It's quite possible that in your a/c model every factor has not been simulated. I'm certain in a real life situation you would not get a "false" oxygen mask deployment.

To try and simulate cabin pressurisation and oxygen deployment is really quite extensive. For example in the VC10 panel updates available on Avsim there are some 50 different gauge elements needed to control them and there are still a few more to write up!! Every possible scenario has to be considered to accurately model the systems even though they may never be activated in the sim. Although they can be and the model does provide for unannounced emergencies it also simulates hypoxia. So you really do have only a few seconds to deal with the problem before the screen goes black. You "wake up" again at 15,000ft hopefully not with your nose pointing towards a mountain top!

 

Remember also that for you as the pilot it is mandatory to be on oxygen at 10,000ft or above. So if you were flying in or out of Cusco for example you actually have a reverse pressurisation scenario.

On the oxygen panel displayed above there are three deployment options:-

1. Below a cabin altitude of 14,000ft the crew can pull either the red or green knob to manually activate the masks.

2. Above a cabin altitude of 14,000ft the masks are activated automatically, the green knob pops out and the flow indicator is activated.

3. Above a cabin altitude of 17,000ft the masks are activated automatically, the red knob pops out and the flow indicator is activated.

 

So in cases 2 and 3 the oxygen auto presentation, cabin height gauge and altitude warning horn are all activated by the same single source. So it's very unlikely that there would not be agreement between them all.

Case 1 is generally reserved for therapeutic oxygen therefore the crew know that a mask or multiples thereof have been presented.

 

It's quite possible that in your a/c model every factor has not been simulated. I'm certain in a real life situation you would not get a "false" oxygen mask deployment.

To try and simulate cabin pressurisation and oxygen deployment is really quite extensive. For example in the VC10 panel updates available on Avsim there are some 50 different gauge elements needed to control them and there are still a few more to write up!! Every possible scenario has to be considered to accurately model the systems even though they may never be activated in the sim. Although they can be and the model does provide for unannounced emergencies it also simulates hypoxia. So you really do have only a few seconds to deal with the problem before the screen goes black. You "wake up" again at 15,000ft hopefully not with your nose pointing towards a mountain top!

 

Remember also that for you as the pilot it is mandatory to be on oxygen at 10,000ft or above. So if you were flying in or out of Cusco for example you actually have a reverse pressurisation scenario.

 

Very interesting information Vololiberista! Thanks much!

 

Actually, I think it would be VERY interesting for them to try simulating hypoxia by taking all the definitions for the controls in the cockpit and "randomizing" them increasingly with the increasing onset of simulated hypoxia :)

 

So If you hit the "Standardized Barometric" button on the barometer control, the Autopilot would disengage, or if you extended flaps, the thrust reverser would try to engage :)

 

Just fading out the screen wouldn't go far enough simulate true disorientation... They could even start playing random music of increasing volume on the headset, and have someone constantly knocking on the flight deck door even though no one is there :)

. They could even start playing random music of increasing volume on the headset, and have someone constantly knocking on the flight deck door even though no one is there :)

One of the guys over on the FSDevelooper forums was toying with that very idea!

Here is an extract from an article found on www.the airline pilots.com

 

From a human factors point of view, once you notice a pressurisation warning, you need to quickly don your oxygen mask. So your well-practised rule should always be:

• Pressurisation warning.
  
• Don mask.
  
• Descend (terrain permitting).
  
• Solve the problem.
  

Variability of Symptoms: Larger aircraft are not immune. Cabin alerts are fallible and hypoxia symptoms are insidious and variable.

Even if cabin altitude alerts function correctly, time of useful consciousness may be less than expected for a given altitude. In 1995, a US Navy P3C departing Japan suffered a rapid decompression to cabin altitude of 24,000 feet in 10 seconds.

Despite the captain's immediate directions, it took the flying pilot some time to don oxygen equipment and initiate descent. He then had difficulty remembering the emergency descent procedure. The non-flying pilot made several radio calls without response, before others realised she had not replaced her headset after donning her smoke mask instead.

The flight engineer became fixated with the un-correctable pressurisation problem and the captain placed his mask on him. The captain, sitting behind the flying pilot, noticed that his fingernails were blue and decided to check the crew aft. They had differing symptoms:

 

 

 

 

·

One member felt light-headed, experienced tingling, started to walk aft but had to sit down.

·

A spare pilot noticed the pressure change, discussed rapid decompression and hypoxia with another member, felt light headed and lost colour vision. He felt nervous as he had no oxygen mask.

·

The navigator felt tingling and was disoriented. He noticed misting in the cabin, became claustrophobic, hyperventilated and fixated on his station.

·

Another crewman felt his ears pop, felt cold, dizzy, confused, disoriented and sat down until another member administered oxygen.

·

Another felt cold, short of breath and suffered an upset stomach.

·

Another attempted to grab a walkaround oxygen bottle but became confused and remembers searching for a toolbox key for a ratchet to unfasten the wall bracket.

·

One passenger became nervous, lay down, began shaking and had blurred vision.

·

Another passenger saw the misting, thought there was a fire, turned blue, had ear pain and noticed everything in slow motion.

·

The spare flight engineer was fascinated when the coffee pot lid exploded and coffee sprayed everywhere. He walked to the flight station, became exhausted, disoriented, saw bright flashing lights and had to be administered oxygen.

·

Another passenger started cleaning the spilled coffee, felt ill, couldn't figure out how to open the toilet door and vomited on himself.

Following this incident, the US Navy recommended "Don Oxygen Mask" as the first item in the Rapid Decompression and Cabin Pressure Light On emergency checklists.

 

QED !!