B747 door opens in mid-air

[CashGap]

A big storm cloud can way 120 MILLION tons.

The fuel dump is environmentally insignificant. You'd see maybe a drop every 100 square feet for a few hundred acres. About what everyone spills Saturday morning when they cut their grass in a housing development that size.

 

[iSamurai]

I think you're mixing some calculations. At 12,000 ft, standard temperature would be +16.2 F/-8.8 C. At 12,000 m, it's -56.5 C/-69.5 F.

As far as oxygen, yes, there is at both altitudes, although at 12,000 meters, there is insufficient pressure to sustain life for long. At sea level, O2 pressure is about 3 lbs/ft2. At 36,000 feet, it's about 0.69 lbs/ft2. Just no way for us to exchange the available oxygen at that low of a pressure.

On a side note, our O2 requirement drops substantially with gains in elevation, and although the volume of oxygen we need is there, we just can't draw it out. The average person breathes in some 11,000 liters of air per day, with the inhaled air having approximately 21% O2 and the exhaled air 15% O2. This equates to an average consumption and use of 350 to 550 liters of oxygen per day at maximum oxygen uptake. As you gain altitude this maximum oxygen uptake(VO2max) decreases by 10% for every 1000m gained above 1200m. 12,000 meters gets us to a VO2max of about 17 ml/kg/min, still above the 7 required for survival, but supplemental oxygen under pressure is still required for anything approximating normal, safe functioning.

dude! who do you work for? that is the beast-est post i've ever read lol. And that ft/metre thing woops my bad! I got confused there. the i heard on the news they said something 12000ft. well they're wrong. I knew the cruising altitude is 1,2kilometres, depending on the allocated altitude. well btw i use the metric system, not familiar with the imperial system. 1000ft idk how much that is

A big storm cloud can way 120 MILLION tons.

The fuel dump is environmentally insignificant. You'd see maybe a drop every 100 square feet for a few hundred acres. About what everyone spills Saturday morning when they cut their grass in a housing development that size.

I think it's significant in this case... the plane was bound for LA and it's laden with fuel. it had 214,140 litres, about 200 metric tonnes. the fuel was dumped over sea, not some piece of wasteland. commercial jets dont have the dump-and-burn system like fighter jets though. although when the fuel reaches terminal velocity it should have enough resistance/friction/forces that it breaks into smaller particles, ie. similar to vapour, and that fuel can travel by wind to other places. just a thought

 

[sushi]

Rule Number 1: Do not fly China Airlines.

Rule Number 2: Obey rule number 1.

Reference the use of supplemental oxygen. Pressurized cabins are to prevent hypoxia from occurring and not to keep your head from exploding.

FWIW, here is the Effective Performance Time (EPT) for some altitudes:

Altitude (ft.) --> EPT (min.)*
18,000 --> 20-30
25,000 --> 3-5
30,000 --> 1-2
40,000 --> <.5

*May be reduced 50% with rapid decompression.

For passengers, smoking and alcohol consumption can decrease the EPT significantly. That is why airlines maintain around a 8,000 foot cabin regardless of how high the plane is above 8,000 feet.

 

[JNB]

Pressurized cabins are to prevent hypoxia from occurring and not to keep your head from exploding.

What, it's not ScannersAir?

FWIW, here is the Effective Performance Time (EPT) for some altitudes:

Altitude (ft.) --> EPT (min.)*
18,000 --> 20-30
25,000 --> 3-5
30,000 --> 1-2
40,000 --> <.5

The EPT tables were the one thing I didn't have at hand (which is essentially all I was trying to get to. Nothing like making a short story long... )


EDIT: Found a photo of the ScannersAir CEO...

 

[MacBoobsPro]

I thought there was a minimum height for dumping fuel legally? 10,000ft or something? Especially over land. Over sea it doesn't matter.

 

[sushi]

The EPT tables were the one thing I didn't have at hand (which is essentially all I was trying to get to. Nothing like making a short story long... )

During training most military pilots will go through altitude chamber training on a regular basis. Within that environment you will experience a slow decompression and are expected to see the signs and put on your oxygen mask as appropriate. You also get to experience a rapid decompression which is kind of cool. And of course some other interesting phenomena.

 

[dmr727]

For passengers, smoking and alcohol consumption can decrease the EPT significantly. That is why airlines maintain around a 8,000 foot cabin regardless of how high the plane is above 8,000 feet.

You're right that the cabin won't get above 8,000 feet (unless operating out of high altitude airports), but it's not because the airlines want it that way. It's a certification requirement for the aircraft itself. For example, many airplanes (especially business jets) have a maximum altitude that exists not because the performance isn't strong enough to go higher, but because it's the highest altitude the plane can go while maintaining a cabin altitude of no higher than 8,000 feet.